@article{kwon_zambrano_pawlak_ford_venditti_2023, title={Aquatic Biodegradation of Poly(beta-Hydroxybutyrate) and Polypropylene Blends with Compatibilizer and the Generation of Micro- and Nano-Plastics on Biodegradation}, volume={4}, ISSN={["1572-8919"]}, DOI={10.1007/s10924-023-02832-y}, journal={JOURNAL OF POLYMERS AND THE ENVIRONMENT}, author={Kwon, Soojin and Zambrano, Marielis C. C. and Pawlak, Joel J. J. and Ford, Ericka and Venditti, Richard A. A.}, year={2023}, month={Apr} }
 @article{kumar_zambrano_peszlen_venditti_pawlak_jameel_gonzalez_2022, title={High-performance sustainable tissue paper from agricultural residue: a case study on fique fibers from Colombia}, volume={6}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-022-04687-3}, abstractNote={Global sustainability megatrends are promoting the utilization of sustainably perceived fibers such as recycled and agricultural residue fibers in hygiene tissue applications. Tissue paper products advertised as sustainable have higher prices and inferior performance than conventional products manufactured from virgin wood fibers. This work demonstrates the feasibility of using agricultural residues from fique plantations (Furcraea microphylla genus) as an alternative to Northern Bleached Softwood Fibers (NBSK) in high-performance hygiene tissue applications. For our study, fiber residues were mechanically cleaned and upgraded to a tissue pulp using a simple pulping and bleaching process. A complete characterization of tissue paper properties (bulk, softness, water absorbency, tensile strength) was performed and compared against the NBSK market pulp. Additionally, fique residue pulp was blended with Bleached Eucalyptus Kraft (BEK) to match the performance of a selected benchmark consisting of 70% BEK and 30% NBSK. Results indicate fique residue bleached pulp has similar fiber morphology and comparable strength properties in terms of the tensile strength (+ 6%) and tear strength (+ 10%), but superior bulk (+ 12%), water absorbency (+ 28%), and softness (−29% TS7 values) than NBSK pulp. A fiber blend of 70% BEK and 30% fique residue showed superior tensile strength (+ 21%), tear strength (+ 54%), bulk (+ 5.5%), water absorbency (+ 1.5%), and softness (−8.7% TS7 values) over a similar fiber blend of BEK and NBSK. Our findings demonstrate that fibers from fique residue can substitute NBSK in hygiene tissue applications. Upgrading residues from fique fibers as raw materials for the tissue industry can bridge the gap between sustainability and product performance, simultaneously opening the possibility of new revenue streams for millions of small farmers in the producing countries.}, journal={CELLULOSE}, author={Kumar, Rajnish and Zambrano, Franklin and Peszlen, Ilona and Venditti, Richard and Pawlak, Joel and Jameel, Hasan and Gonzalez, Ronalds}, year={2022}, month={Jun} }
 @misc{parrilla-lahoz_mahebadevan_kauta_zambrano_pawlak_venditti_reina_duyar_2022, title={Materials challenges and opportunities to address growing micro/ nanoplastics pollution: a review of thermochemical upcycling}, volume={20}, ISSN={["2589-2347"]}, DOI={10.1016/j.mtsust.2022.100200}, abstractNote={Micro/nanoplastics have sparked attention in recent years due to their widespread presence in the environment. Currently, several waste valorization approaches are under development in order to upcycle micro/nanoplastics. Thermal conversion technologies such as pyrolysis, gasification, liquefaction, or hydrothermal carbonization can yield high-value solid products, oil, and gases from plastics waste. The common thermal conversion technologies investigated focus on maximizing the production of oil and gases (such as H2 and CH4) for use as fuel. Except for hydrogen, when these products are used to generate energy, the carbon emissions generated are comparable to those produced by traditional fossil fuels. Herein, we present a review of the current efforts to capture and convert plastic waste into valuable products with an emphasis on identifying the need to develop processes specifically for micro/nanoplastics while also preventing the release of CO2 emissions. We identify the development of efficient catalytic materials as a critical research need for achieving economically viable thermochemical conversion of micro/nanoplastics.}, journal={MATERIALS TODAY SUSTAINABILITY}, author={Parrilla-Lahoz, S. and Mahebadevan, S. and Kauta, M. and Zambrano, M. C. and Pawlak, J. J. and Venditti, R. A. and Reina, T. R. and Duyar, M. S.}, year={2022}, month={Dec} }
 @article{frazier_zambrano_pawlak_gonzalez_2022, title={Methods to assess and control dusting and linting in the paper industry: a review}, volume={1}, ISSN={["1433-3015"]}, DOI={10.1007/s00170-021-08482-5}, journal={INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY}, author={Frazier, Ryen and Zambrano, Franklin and Pawlak, Joel J. and Gonzalez, Ronalds}, year={2022}, month={Jan} }
 @article{kwon_zambrano_venditti_frazier_zambrano_gonzalez_pawlak_2022, title={Microfiber shedding from nonwoven materials including wipes and meltblown nonwovens in air and water environments}, volume={4}, ISSN={["1614-7499"]}, DOI={10.1007/s11356-022-20053-z}, abstractNote={Nonwoven products are widely used in disposable products, such as wipes, diapers, and masks. Microfibers shed from these products in the aquatic and air environment have not been fully described. In the present study, 15 commercial single-use nonwoven products (wipes) and 16 meltblown nonwoven materials produced in a pilot plant were investigated regarding their microfiber generation in aquatic and air environments and compared to selected textile materials and paper tissue materials. Microfibers shed in water were studied using a Launder Ometer equipment (1–65 mg of microfibers per gram material), and microfibers shed in air were evaluated using a dusting testing machine that shakes a piece of the nonwoven back and forth (~ 4 mg of microfibers per gram material). The raw materials and bonding technologies affected the microfiber generation both in water and air conditions. When the commercial nonwovens contained less natural cellulosic fibers, less microfibers were generated. Bonding with hydroentangling and/or double bonding by two different bonding methods could improve the resistance to microfiber generation. Meltblown nonwoven fabrics generated fewer microfibers compared to the other commercial nonwovens studied here, and the manufacturing factors, such as DCD (die-to-collector distance) and air flow rate, affected the tendency of microfiber generation. The results suggest that it is possible to control the tendency of microfiber shedding through the choice of operating parameters during nonwoven manufacturing processes.}, journal={ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH}, author={Kwon, Soojin and Zambrano, Marielis C. and Venditti, Richard A. and Frazier, Ryen and Zambrano, Franklin and Gonzalez, Ronalds W. and Pawlak, Joel J.}, year={2022}, month={Apr} }
 @misc{pawlak_frazier_vera_wang_gonzalez_2022, title={Review: The Softness of Hygiene Tissue}, volume={17}, ISSN={["1930-2126"]}, DOI={10.15376/biores.17.2.Pawlak}, abstractNote={The hygiene tissue industry has an extensive global market that is quickly growing. Market research has indicated that softness is one of consumers’ most highly desired properties. For certain hygiene tissue products (specifically bath tissue), this property can influence prices. A better understanding of the science of softness would allow companies to engineer soft tissue more economically and efficiently. Softness is a subjective perception related to physical aspects that make it challenging to express and measure. Human handfeel panel testing, which ranks the specimens through physical tests, has been recognized as the most reliable method to measure tissue softness. Much effort has been expanded in correlating the panel test results with some measurable properties. In this regard, equipment has been recently developed by combining several different mechanical, surface, and acoustic properties to characterize softness. In comparison with panel tests, these instruments (e.g., tissue softness analyzer) have been found to give equivalent softness metrics. A combination of materials selection and manufacturing operations are used to create softer tissue sheets. This paper reviews the sensation of softness as perceived by the human touch, techniques for measuring softness, the influence of fiber on softness, manufacturing techniques, and additives used for softness enhancement.}, number={2}, journal={BIORESOURCES}, author={Pawlak, Joel J. and Frazier, Ryen and Vera, Ramon E. and Wang, Yuhan and Gonzalez, Ronalds}, year={2022}, month={May}, pages={3509–3550} }
 @article{frazier_zambrano_pawlak_peszlen_welsford_gonzalez_2022, title={The tissue dust analysis system: a new device and methodology to quantify dusting and linting propensity in hygiene tissue papers}, volume={8}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-022-04779-0}, abstractNote={Paper dusting, which occurs when a tissue web releases unbound and loosely bound fibers or filler particles during tissue-making or product manufacturing, has an overall negative impact, causing safety hazards, machine runnability difficulties, and product quality issues. To date, there are no well-established industry standards to quantify dusting/linting propensities in finished tissue products, thus evaluating the effectiveness of dust/lint control programs is challenging yet intriguing. This research aims to fill this gap by developing a methodology to characterize dusting in tissue papers. We have developed a device prototype (named the Tissue Dust Collector) and a methodology that together have been named the Tissue Dust Analysis System (TDAS), which aims at quantifying the propensity for tissue-grade paper products to generate dust/lint in a controlled and reproducible manner. Two samples, corresponding to commercial products with a low and high linting propensity, were tested using the proposed device and methodology, and the released particles were quantified and characterized. The device and methodology provided reproducible results for simulated consumer handling and product manufacturing scenarios. By changing the instrument's motor frequency, the force of agitation changes, mimicking/simulating consumer (60 strokes per min, spm) and producer/manufacturing (180 spm) handling scenarios (though manufacturing processes are much faster in practice). Particle counts at each level for each product showed reproducible values differentiable at different agitation levels. Adopting the proposed Tissue Dust Analysis System may help to characterize and understand the mechanisms behind dusting to create dust-control strategies that can alleviate this issue at its various sources or simply allow tissue paper manufacturers to compare and advertise their products based on dusting propensity.}, journal={CELLULOSE}, author={Frazier, Ryen and Zambrano, Franklin and Pawlak, Joel J. and Peszlen, Ilona and Welsford, David and Gonzalez, Ronalds}, year={2022}, month={Aug} }
 @misc{brown_pawlak_grunden_2021, title={Bacterial valorization of pulp and paper industry process streams and waste}, volume={105}, ISSN={["1432-0614"]}, url={https://doi.org/10.1007/s00253-021-11107-2}, DOI={10.1007/s00253-021-11107-2}, number={4}, journal={APPLIED MICROBIOLOGY AND BIOTECHNOLOGY}, publisher={Springer Science and Business Media LLC}, author={Brown, Dylan M. and Pawlak, Joel and Grunden, Amy M.}, year={2021}, month={Feb}, pages={1345–1363} }
 @article{kwon_zambrano_pawlak_venditti_2021, title={Effect of lignocellulosic fiber composition on the aquatic biodegradation of wood pulps and the isolated cellulose, hemicellulose and lignin components: kinetic modelling of the biodegradation process}, volume={28}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-021-03680-6}, DOI={10.1007/s10570-021-03680-6}, number={5}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Kwon, Soojin and Zambrano, Marielis C. and Pawlak, Joel J. and Venditti, Richard A.}, year={2021}, month={Feb}, pages={2863–2877} }
 @article{salam_zambrano_venditti_pawlak_2021, title={Hemicellulose and Starch Citrate Chitosan Foam Adsorbents for Removal of Arsenic and Other Heavy Metals from Contaminated Water}, volume={16}, ISSN={["1930-2126"]}, DOI={10.15376/biores.16.3.5628-5645}, abstractNote={Arsenic and other heavy metal contaminants in water are a significant global health threat. In this study, low-cost, sulfur-free, sustainable, water-insoluble materials with heavy metal remediation properties were produced from renewable resources such as starch, xylan, citric acid, and chitosan. Synthesized starch citrate-chitosan (SCC) foam and xylan citrate-chitosan (XCC) foam were flexible, porous, and elastic. The foams’ arsenic uptake in water was significantly greater than five different commercial metal remediating agents. The mercury and lead uptakes with the synthesized foams were similar to the performance of a commercial sulfur-based product, SorbaTech 450 (ST450). However, the cadmium and selenium uptakes were comparatively lower. The complexation of arsenic with oxygen and nitrogen of the SCC foam was shown with time-of-flight secondary ion mass spectrometry (TOF-SIMS). The XCC foam was also shown to adsorb potassium iodide (KI) at a similar rate to sodium chloride. This may be used to remediate water contaminated with radioactive materials, such as iodine 131.}, number={3}, journal={BIORESOURCES}, author={Salam, Abdus and Zambrano, Marielis C. and Venditti, Richard A. and Pawlak, Joel}, year={2021}, month={Aug}, pages={5628–5645} }
 @article{zambrano_pawlak_daystar_ankeny_venditti_2021, title={Impact of dyes and finishes on the aquatic biodegradability of cotton textile fibers and microfibers released on laundering clothes: Correlations between enzyme adsorption and activity and biodegradation rates}, volume={165}, ISSN={["1879-3363"]}, DOI={10.1016/j.marpolbul.2021.112030}, abstractNote={The presence and biodegradability of textile microfibers shed during laundering or use is an important environmental issue. In this research, the influence of common textile finishes on the persistence of cotton fibers in an aerobic aquatic environment was assessed. The biodegradation of cotton knitted fabrics with different finishes, silicone softener, durable press, water repellent, and a blue reactive dye was evaluated. The rate of biodegradation decreased with durable press and water repellant finishing treatments. In terms of the final extent of biodegradation, there was no significant difference between the samples. All samples reached more than 60% biodegradation in 102 days. The biodegradation rates were in agreement with observed trends of the same samples for cellulase mediated hydrolysis and cellulase adsorption experiments, indicating the finishes impact the initial adsorption of enzymes excreted by the microorganisms and the initial rates of biodegradation, however despite this the cellulosic material maintains its biodegradability.}, journal={MARINE POLLUTION BULLETIN}, author={Zambrano, Marielis C. and Pawlak, Joel J. and Daystar, Jesse and Ankeny, Mary and Venditti, Richard A.}, year={2021}, month={Apr} }
 @article{zambrano_pawlak_daystar_ankeny_venditti_2021, title={Impact of dyes and finishes on the microfibers released on the laundering of cotton knitted fabrics}, volume={272}, ISSN={0269-7491}, url={http://dx.doi.org/10.1016/j.envpol.2020.115998}, DOI={10.1016/j.envpol.2020.115998}, abstractNote={Abstract The influence of common textile finishes on cotton fabrics on the generation of microfibers during laundering was assessed. Microfiber release was determined to be in the range of 9000–14,000 particles per gram of cotton fabric. Cotton knitted fabrics treated with softener and durable press generate more microfibers (1.30–1.63 mg/g fabric) during laundering by mass and number than untreated fabric (0.73 mg/g fabric). The fabrics treated with softener generated the longest average microfiber length (0.86 mm), whereas durable press and water repellent treatments produced the shortest average microfiber length (0.62 and 0.63 mm, respectively). In general, the changes in the mechanical properties of the fibers and fabrics due to the finishing treatments are the main factor affecting the microfiber release. The abrasion resistance of the fabrics decreases for durable press treatments and water repellent treatments due to the brittleness in the structure originated by the crosslinking treatment. In the case of the softener treatment, the fabric surface is soft and smooth decreasing the friction coefficient between fibers favoring the fibers loosening from the textile and resulting in a high tendency for fuzz formation and microfiber release. These findings are useful for the textile industry in the design and selection of materials and treatments for the reduction of synthetic or natural microfiber shedding from textiles.}, journal={Environmental Pollution}, publisher={Elsevier BV}, author={Zambrano, Marielis C. and Pawlak, Joel J. and Daystar, Jesse and Ankeny, Mary and Venditti, Richard A.}, year={2021}, month={Mar}, pages={115998} }
 @article{kwon_zambrano_venditti_frazier_zambrano_gonzalez_pawlak_2021, title={Waterborne and Airborne Microfibers Shed from Non-Woven Materials in Water and Air Environments}, volume={12}, url={https://doi.org/10.21203/rs.3.rs-996055/v1}, DOI={10.21203/rs.3.rs-996055/v1}, abstractNote={Abstract Nonwoven products are widely used in various fields, including many disposable products, such as wipes, diapers, and masks. However, microfibers shed from these products in the aquatic and air environment have not been fully described. In the present study, several commercial single-use nonwoven products and a series of meltblown nonwoven materials produced in a pilot plant were investigated regarding their microfiber generation during their use in aquatic and air environments. Microfibers shed in water were studied using a Launder Ometer equipment (1- 65 mg of microfibers per gram material), and microfibers shed in air were evaluated using a dusting testing machine that shakes a piece of the nonwoven back and forth (~0 to 6000 microfibers (4 mg of microfibers) per gram material). The raw materials and bonding technologies applied to the commercial nonwovens affected the microfiber generation both in water and air conditions. Meltblown nonwoven fabrics generated fewer microfibers compared to the other commercial nonwovens studied here, and the manufacturing factors, such as DCD (Die to collector distance) and air flow rate, affected the tendency of microfiber generation. Microfibers of nonwovens shed in water and air environment were compared to selected textile materials and paper tissue materials. The results herein suggest that it is possible to control the tendency of microfiber shedding through the choice of operating parameters during nonwoven manufacturing processes.}, publisher={Research Square Platform LLC}, author={Kwon, Soojin and Zambrano, Marielis C. and Venditti, Richard A. and Frazier, Ryen and Zambrano, Franklin and Gonzalez, Ronalds W. and Pawlak, Joel Justin}, year={2021}, month={Dec} }
 @article{zambrano_pawlak_daystar_ankeny_goller_venditti_2020, title={Aerobic biodegradation in freshwater and marine environments of textile microfibers generated in clothes laundering: Effects of cellulose and polyester-based microfibers on the microbiome}, volume={151}, ISSN={0025-326X}, url={http://dx.doi.org/10.1016/j.marpolbul.2019.110826}, DOI={10.1016/j.marpolbul.2019.110826}, abstractNote={The aerobic biodegradation of common textiles that shed microfibers during laundering was evaluated under the action of microbes found in the environment, such as lake and seawater, and activated sludge at a low concentration from a wastewater treatment plant (WWTP). Under these conditions, the biodegradation potential was the same in all the experiments: Microcrystalline Cellulose (MCC) > Cotton > Rayon > Polyester/Cotton ≫ Polyester. Nevertheless, for cotton and rayon yarns, >70% biodegradation was achieved with activated sludge at low concentration and lake water, whereas in seawater, about 50% degradation was reached. Polyester did not appreciably degrade. The biodegradation results herein indicate potential not absolutes in nature. The bacterial diversity analyses in the different biodegradation inoculums show that there are distinct bacterial communities related to the assimilation and mineralization of complex carbohydrates that were promoted with the cellulosic MCC, cotton, and rayon samples different than the polyester sample.}, journal={Marine Pollution Bulletin}, publisher={Elsevier BV}, author={Zambrano, Marielis C. and Pawlak, Joel J. and Daystar, Jesse and Ankeny, Mary and Goller, Carlos C. and Venditti, Richard A.}, year={2020}, month={Feb}, pages={110826} }
 @article{geng_venditti_pawlak_chang_pal_ford_2020, title={Carboxymethylation of hemicellulose isolated from poplar (Populus grandidentata) and its potential in water-soluble oxygen barrier films}, volume={27}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-020-02993-2}, DOI={10.1007/s10570-020-02993-2}, number={6}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Geng, Wenhui and Venditti, Richard A. and Pawlak, Joel J. and Chang, Hou-ming and Pal, Lokendra and Ford, Ericka}, year={2020}, month={Jan}, pages={3359–3377} }
 @article{assis_pawlak_pal_jameel_reisinger_kavalew_campbell_pawlowska_gonzalez_2020, title={Comparison between uncreped and creped handsheets on tissue paper properties using a creping simulator unit}, volume={27}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-020-03163-0}, number={10}, journal={CELLULOSE}, author={Assis, Tiago and Pawlak, Joel and Pal, Lokendra and Jameel, Hasan and Reisinger, Lee W. and Kavalew, Dale and Campbell, Clayton and Pawlowska, Lucyna and Gonzalez, Ronalds W.}, year={2020}, month={Jul}, pages={5981–5999} }
 @article{zambrano_pawlak_venditti_2020, title={Effects of Chemical and Morphological Structure on Biodegradability of Fibers, Fabrics, and Other Polymeric Materials}, volume={15}, ISSN={["1930-2126"]}, DOI={10.15376/biores.15.4.Zambrano}, abstractNote={The biodegradability of polymers depends on several factors. However, the most critical aspects are the accessibility of the structure for moisture and enzyme diffusion and the capacity of the microbes in the environment to assimilate the final monomers. The accessibility of the polymer structure to enzymes and water depends primarily on crystallinity, hydrophobicity, and the steric effects of the side groups in the polymer backbone. In general, biologically synthesized polymers are readily biodegradable in natural environments but synthetic polymers are either less biodegradable or degrade very slowly. However, such generalizations should be avoided. To understand the compatibility of biomaterials and the environment, both the disintegration step of the biodegradation process and the assimilation and mineralization of these fragments by microorganisms must be investigated. Mineralization occurs when the oligomers and monomers assimilated within the cells are converted to CO2 and H2O (aerobic), and CO2, CH4, and H2O (anaerobic). Although the disintegration of the polymeric structure limits the biodegradation rate and is most easily detected, the final pieces may accumulate in the environment if they are not fully mineralized. Such accumulation could contribute to an issue with microplastics that may be much more difficult to address than the removal of macroscopic, large polymer-based debris.}, number={4}, journal={BIORESOURCES}, author={Zambrano, Marielis C. and Pawlak, Joel J. and Venditti, Richard A.}, year={2020}, month={Nov}, pages={9786–9833} }
 @article{geng_venditti_pawlak_de assis_gonzalez_phillips_chang_2020, title={Techno-economic analysis of hemicellulose extraction from different types of lignocellulosic feedstocks and strategies for cost optimization}, volume={14}, ISBN={1932-1031}, ISSN={1932-104X 1932-1031}, url={http://dx.doi.org/10.1002/bbb.2054}, DOI={10.1002/bbb.2054}, number={2}, journal={BIOFUELS BIOPRODUCTS & BIOREFINING-BIOFPR}, publisher={Wiley}, author={Geng, Wenhui and Venditti, Richard A. and Pawlak, Joel J. and De Assis, Tiago and Gonzalez, Ronalds W. and Phillips, Richard B. and Chang, Hou-min}, year={2020}, month={Mar}, pages={225–241} }
 @article{sadeghifar_venditti_pawlak_jur_2019, title={Bi-component carbohydrate and lignin nanoparticle production from bio-refinery lignin: A rapid and green method}, volume={14}, ISSN={1930-2126 1930-2126}, url={http://dx.doi.org/10.15376/biores.14.3.6179-6185}, DOI={10.15376/biores.14.3.6179-6185}, abstractNote={A rapid and green preparation of lignin nanoparticles was demonstrated starting from bio-refinery lignin containing grafted carbohydrates. The particles were prepared by recovering a fraction of the lignin, which contained 24% carbohydrate (by weight) as the insoluble fraction in 0.5 M NaOH. The carbohydrate content of this fraction was verified with a wet chemistry analytical technique, nuclear magnetic resonance, and X-ray diffraction. This fraction was then dissolved in a NaOH/urea/water system and added dropwise to water under a high shear, which rapidly formed precipitated particles in a size range of approximately 100 nm. This carbohydrate-containing fraction of the lignin was soluble in a green solvent system that was not suited for lignin alone. The generated particles were stable in different organic solvents and water. Overall, the dissolution of the bio-refinery lignin in the NaOH/urea/water system, followed by precipitation in water can be regarded as a green and rapid method to produce stable nanoparticles. The generated nanoparticles, containing both carbohydrates and lignin, are expected to have unique applications because of their bi-component nature. Furthermore, this is the first publication to show how materials with high levels of lignin can be solubilized in solvents that are conventionally used for cellulose.}, number={3}, journal={BioResources}, publisher={BioResources}, author={Sadeghifar, Hasan and Venditti, Richard A. and Pawlak, Joel J. and Jur, Jesse}, year={2019}, month={Jun}, pages={6179–6185} }
 @article{sadeghifar_venditti_pawlak_jur_2019, title={Cellulose Transparent and Flexible Films Prepared from DMAc/LiCl Solutions}, volume={14}, ISSN={["1930-2126"]}, DOI={10.15376/biores.14.4.9021-9032}, abstractNote={Cellulose transparent and flexible film was prepared by dissolving micro-crystalline cellulose powder in Dimethylacetamide/Lithium Chloride (DMAc/LiCl) followed by regeneration in acetone and subsequent washing with water. The solution was cast on a glass plate. The interactions of water molecules and the swollen cellulose in the gel were examined by differential scanning calorimetry, DSC. An increased melting point of water in the gel indicated the presence of stronger bonding between water and cellulose than in the non-modified cellulose. The prepared dried films had 63 g/m2 weight and 0.06 mm thickness with 1.14 g/cm3 density.The prepared dry film exhibited high transparency, around 95% with visible light. The transparency and mechanical properties of the films were stable at high temperature (120°C) and exposure to UV irradiation. Thermal analysis of the prepared sample indicated film stability up to 275 °C. The tensile strength of the cellulose film was around 120 MPa with about 10% strain to break. The mechanical properties of the films were stable in alkali and acidic solutions.}, number={4}, journal={BIORESOURCES}, author={Sadeghifar, Hasan and Venditti, Richard and Pawlak, Joel J. and Jur, Jesse}, year={2019}, month={Nov}, pages={9021–9032} }
 @article{assi_pawlak_pal_jameel_venditti_reisinger_kavalew_gonzalez_2019, title={Comparison of Wood and Non-Wood Market Pulps for Tissue Paper Application}, volume={14}, ISSN={["1930-2126"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85076457460&partnerID=MN8TOARS}, DOI={10.15376/biores.14.3.6781-6810}, abstractNote={A comparison among ten market pulps at a laboratory scale using uncreped tissue handsheets was performed to study the performance of wood and non-wood pulps for tissue manufacturing, evaluate what fiber features are desired for a specific tissue property, and determine how non-wood pulps can be used to replace or complement wood pulps in tissue products. A characterization of the fiber morphology and handsheet properties (softness, water absorbency, and strength) was performed at different mechanical refining levels. The results showed that the fiber morphology had a major impact on tissue properties. Market pulps with a combination of long fibers, high coarseness, and low fines content can provide superior bulk and water absorbency. Short fibers with thin cell walls and low fines content can impart superior softness. Bleached bamboo soda pulp can replace hardwood and softwood pulps to provide an excellent combination of water absorbency and strength. Bleached bamboo soda pulp can also replace Northern bleached softwood kraft (NBSK) pulp to impart strength without sacrificing softness. Bleached and semi-bleached wheat straw soda pulps presented a similar combination of softness and strength as Southern bleached hardwood kraft (SBHK) pulp. The wheat straw pulps can be used to replace deinked pulp (DIP) pulp to impart intermediate levels of water absorbency and strength.}, number={3}, journal={BIORESOURCES}, author={Assi, Tiago and Pawlak, Joel and Pal, Lokendra and Jameel, Hasan and Venditti, Richard and Reisinger, Lee W. and Kavalew, Dale and Gonzalez, Ronalds W.}, year={2019}, month={Aug}, pages={6781–6810} }
 @article{wang_zambrano_venditti_dasmohapatra_de assis_reisinger_pawlak_gonzalez_2019, title={Effect of Pulp Properties, Drying Technology, and Sustainability on Bath Tissue Performance and Shelf Price}, volume={14}, ISSN={["1930-2126"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85075253887&partnerID=MN8TOARS}, DOI={10.15376/biores.14.4.9410-9428}, abstractNote={The relationship between the types of pulp, the tissue making technologies, and shelf price of bath tissue was evaluated for the North American market. Twenty-four market tissue samples (representing approximately 80% of the current market offering) were sourced and analyzed along with their nationwide price information. Pulp composition, drying technologies, market share, sustainability advertising, and tissue properties were evaluated. Tissue properties, including softness, ball burst strength, water absorbency, density, tensile strength, and tensile modulus were measured. Among all the drying technologies, creped through-air dry (CTAD) and creped through-air dry belt (CTADB) seemed to improve tissue softness most. The UCTAD maximized tissue bulk by drying the tissue web solely using a through-air (TAD) cylinder. Tissue samples with freeness between 575 to 650 mL seemed to have their properties improved more significantly through advanced drying technologies. It was found that the retail prices of these bath tissues were directly related to softness, bulkiness, water absorbency, and basis weight. A mathematical model was conducted to predict the retail price of bath tissue (based on product performance and attributes). This paper also identified the effect of “sustainability” on the retail price.}, number={4}, journal={BIORESOURCES}, author={Wang, Yuhan and Zambrano, Franklin and Venditti, Richard and Dasmohapatra, Sudipta and De Assis, Tiago and Reisinger, Lee and Pawlak, Joel and Gonzalez, Ronalds}, year={2019}, month={Nov}, pages={9410–9428} }
 @article{zambrano_pawlak_daystar_ankeny_cheng_venditti_2019, title={Microfibers generated from the laundering of cotton, rayon and polyester based fabrics and their aquatic biodegradation}, volume={142}, ISSN={0025-326X}, url={http://dx.doi.org/10.1016/j.marpolbul.2019.02.062}, DOI={10.1016/j.marpolbul.2019.02.062}, abstractNote={The effect of fiber type (cotton, polyester, and rayon), temperature, and use of detergent on the number of microfibers released during laundering of knitted fabrics were studied during accelerated laboratory washing (Launder-Ometer) and home laundering experiments. Polyester and cellulose-based fabrics all shed significant amounts of microfibers and shedding levels were increased with higher water temperature and detergent use. Cellulose-based fabrics released more microfibers (0.2–4 mg/g fabric) during accelerated laundering than polyester (0.1–1 mg/g fabric). Using well-controlled aquatic biodegradation experiments it was shown that cotton and rayon microfibers are expected to degrade in natural aquatic aerobic environments whereas polyester microfibers are expected to persist in the environment for long periods of time.}, journal={Marine Pollution Bulletin}, publisher={Elsevier BV}, author={Zambrano, Marielis C. and Pawlak, Joel J. and Daystar, Jesse and Ankeny, Mary and Cheng, Jay J. and Venditti, Richard A.}, year={2019}, month={May}, pages={394–407} }
 @article{geng_narron_jiang_pawlak_chang_park_jameel_venditti_2019, title={The influence of lignin content and structure on hemicellulose alkaline extraction for non-wood and hardwood lignocellulosic biomass}, volume={26}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-019-02261-y}, DOI={10.1007/s10570-019-02261-y}, number={5}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Geng, Wenhui and Narron, Robert and Jiang, Xiao and Pawlak, Joel J. and Chang, Hou-min and Park, Sunkyu and Jameel, Hasan and Venditti, Richard A.}, year={2019}, month={Jan}, pages={3219–3230} }
 @article{wang_de assis_zambrano_pal_venditti_dasmohapatra_pawlak_gonzalez_2018, title={Relationship between human perception of softness and instrument measurements}, volume={14}, ISSN={1930-2126 1930-2126}, url={http://dx.doi.org/10.15376/biores.14.1.780-795}, DOI={10.15376/biores.14.1.780-795}, abstractNote={Softness, as a subjective perception, is difficult to define and quantify. For decades, panel tests have been used to judge differences in the softness of hygiene tissue samples. Panel tests can be a time-consuming and expensive process. A number of protocols have been developed to quantify the physical properties of tissues associated with softness. The Tissue Softness Analyzer (TSA) by Emtec has gained popularity in characterizing the physical properties of tissues associated with softness. The instrument was designed with softness in mind and attempts to simulate the touch of the human hand. There is currently no comprehensive study that compares the results from a TSA and human panel. In this work, panel tests were used to validate the performance of the TSA with bath tissue. It was determined that one component of the TSA measurements (TS7) linearly correlated with the panel results. Among all of the algorithms available for use with the TSA, the TP2 algorithm most accurately predicted the panel scores. The TSA performed better in predicting the softness of the samples that were dried with a conventional wet press or creped-through air-dryer.}, number={1}, journal={BioResources}, publisher={BioResources}, author={Wang, Yuhan and de Assis, Tiago and Zambrano, Franklin and Pal, Lokendra and Venditti, Richard and Dasmohapatra, Sudipta and Pawlak, Joel and Gonzalez, Ronalds}, year={2018}, month={Dec}, pages={780–795} }
 @misc{de assis_reisinger_pal_pawlak_jameel_gonzalez_2018, title={Understanding the effect of machine technology and cellulosic fibers on tissue properties - a review}, volume={13}, number={2}, journal={BioResources}, author={De Assis, T. and Reisinger, L. W. and Pal, L. and Pawlak, J. and Jameel, H. and Gonzalez, R. W.}, year={2018} }
 @article{sadeghifar_venditti_jur_gorga_pawlak_2017, title={Cellulose-Lignin Biodegradable and Flexible UV Protection Film}, volume={5}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/acssuschemeng.6b02003}, DOI={10.1021/acssuschemeng.6b02003}, abstractNote={There is significant interest in biodegradable and transparent UV protection films from renewable resources for many different applications. Herein, the preparation and characterization of semitransparent flexible cellulose films containing low amounts of covalently bonded lignin with UV-blocking properties are described. Azide modified cellulose dissolved in dimethylacetamide/lithium chloride (DMAc/LiCl) was reacted with propargylated lignin to produce 0.5%, 1%, and 2% by weight lignin containing materials. Cellulose-lignin films were prepared by regeneration in acetone. These covalently bonded cellulose-lignin films were homogeneous, unlike the simple blends of cellulose and lignin. Prepared films showed high UV protection ability. Cellulose film containing 2% lignin showed 100% protection of UV-B (280–320 nm) and more than 90% of UV-A (320–400 nm). The UV protection of prepared films was persistent when exposed to thermal treatment at 120 °C and UV irradiation. Thermogravimetric analysis of the films showed minimal mass loss up to 275 °C. The tensile strength of the neat cellulose film was around 120 MPa with about a 10% strain to break. Treated cellulose films with 2% lignin showed lower tensile strength (90 MPa). The described methods demonstrate a straightforward procedure to produce renewable based cellulose-lignin UV-light-blocking films.}, number={1}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Sadeghifar, Hasan and Venditti, Richard and Jur, Jesse and Gorga, Russell E. and Pawlak, Joel J.}, year={2017}, month={Nov}, pages={625–631} }
 @article{whitham_schulte_bobay_bruno-barcena_chinn_flickinger_pawlak_grunden_2017, title={Characterization of Clostridium ljungdahlii OTA1: a non-autotrophic hyper ethanol-producing strain}, volume={101}, ISSN={0175-7598 1432-0614}, url={http://dx.doi.org/10.1007/S00253-016-7978-6}, DOI={10.1007/S00253-016-7978-6}, number={4}, journal={Applied Microbiology and Biotechnology}, publisher={Springer Nature}, author={Whitham, Jason M. and Schulte, Mark J. and Bobay, Benjamin G. and Bruno-Barcena, Jose M. and Chinn, Mari S. and Flickinger, Michael C. and Pawlak, Joel J. and Grunden, Amy M.}, year={2017}, month={Feb}, pages={1615–1630} }
 @article{bernal_pawlak_flickinger_2017, title={Microbial Paper: Cellulose Fiber-based Photo-Absorber Producing Hydrogen Gas from Acetate using Dry-Stabilized Rhodopseudomonas palustris}, volume={12}, ISSN={["1930-2126"]}, DOI={10.15376/biores.12.2.4013-4030}, abstractNote={The microstructure and reactivity of a novel nonwoven cellulose fiber cellular biocomposite (microbial paper) was studied relative to long-term stabilization of potentially any microorganism. Cells were incorporated during the papermaking process as an integral component of a highly porous cellular biocomposite that can be dry stabilized. Hydrogen gas production from acetate via the activity of the nitrogenases in Rhodopseudomonas palustris CGA009, entrapped at a very high concentration, in hand-made microbial paper was sustained for > 1000 h at a rate of 4.0 ± 0.28 mmol H2/m2 h-1 following rehydration. This rate is 2x and 10x greater than previously reported H2 production rates by Rps. palustris latex coatings that were dried on polyester and non-dried formulations applied to the surface of paper, respectively. By vacuum-dewatering and controlled drying steps to the microbial papermaking process and incorporating blends of microfibrillar (MFC), softwood (SW), and hardwood (HW) cellulose fibers, microbial paper films were fabricated that produced H2 gas at 3.94 ± 1.07 mmol H2/m2 h-1 and retain up to 60 mg/m-2 dry cell weight (DCW) of Rps. palustris. The MFC content appears to determine the final cell load and may affect gas/moisture mass transfer properties of the biocomposite.}, number={2}, journal={BIORESOURCES}, author={Bernal, Oscar I. and Pawlak, Joel J. and Flickinger, Michael C.}, year={2017}, pages={4013–4030} }
 @article{mathews_grunden_pawlak_2016, title={Degradation of lignocellulose and lignin by Paenibacillus glucanolyticus}, volume={110}, ISSN={["1879-0208"]}, DOI={10.1016/j.ibiod.2016.02.012}, abstractNote={Lignocellulose is an abundant renewable carbon source that has been used for fuel and chemical production. Lignocellulose refers to the plant cell wall and is composed of cellulose, hemicellulose, and lignin. Lignin is a recalcitrant amorphous aromatic compound. Paenibacillus glucanolyticus SLM1, a facultative anaerobe that grows optimally at pH 9, was isolated from pulp mill waste. Initial characterization showed that this bacterium could degrade cellulose and hemicellulose and also suggested that it may be able to degrade lignin. This work examines the ability of P. glucanolyticus SLM1 and the type strain P. glucanolyticus 5162 to degrade lignocellulose, lignin, and aromatic lignin-related compounds using growth studies, dye degradation assays, GC–MS, and GPC. Our results show that both strains of P. glucanolyticus can degrade aromatic lignin-related compounds under aerobic and anaerobic conditions. These strains can also degrade polymeric lignin under anaerobic conditions. However, only P. glucanolyticus SLM1 can also degrade polymeric lignin under aerobic conditions.}, journal={INTERNATIONAL BIODETERIORATION & BIODEGRADATION}, author={Mathews, Stephanie L. and Grunden, Amy M. and Pawlak, Joel}, year={2016}, month={May}, pages={79–86} }
 @article{mathews_pawlak_grunden_2015, title={Bacterial biodegradation and bioconversion of industrial lignocellulosic streams}, volume={99}, ISSN={0175-7598 1432-0614}, url={http://dx.doi.org/10.1007/S00253-015-6471-Y}, DOI={10.1007/S00253-015-6471-Y}, number={7}, journal={Applied Microbiology and Biotechnology}, publisher={Springer Science and Business Media LLC}, author={Mathews, Stephanie L. and Pawlak, Joel and Grunden, Amy M.}, year={2015}, month={Feb}, pages={2939–2954} }
 @article{whitham_tirado-acevedo_chinn_pawlak_grunden_2015, title={Metabolic Response of Clostridium ljungdahlii to Oxygen Exposure}, volume={81}, ISSN={0099-2240 1098-5336}, url={http://dx.doi.org/10.1128/AEM.02491-15}, DOI={10.1128/aem.02491-15}, abstractNote={Clostridium ljungdahlii is an important synthesis gas-fermenting bacterium used in the biofuels industry, and a preliminary investigation showed that it has some tolerance to oxygen when cultured in rich mixotrophic medium. Batch cultures not only continue to grow and consume H2, CO, and fructose after 8% O2 exposure, but fermentation product analysis revealed an increase in ethanol concentration and decreased acetate concentration compared to non-oxygen-exposed cultures. In this study, the mechanisms for higher ethanol production and oxygen/reactive oxygen species (ROS) detoxification were identified using a combination of fermentation, transcriptome sequencing (RNA-seq) differential expression, and enzyme activity analyses. The results indicate that the higher ethanol and lower acetate concentrations were due to the carboxylic acid reductase activity of a more highly expressed predicted aldehyde oxidoreductase (CLJU_c24130) and that C. ljungdahlii's primary defense upon oxygen exposure is a predicted rubrerythrin (CLJU_c39340). The metabolic responses of higher ethanol production and oxygen/ROS detoxification were found to be linked by cofactor management and substrate and energy metabolism. This study contributes new insights into the physiology and metabolism of C. ljungdahlii and provides new genetic targets to generate C. ljungdahlii strains that produce more ethanol and are more tolerant to syngas contaminants.}, number={24}, journal={Applied and Environmental Microbiology}, publisher={American Society for Microbiology}, author={Whitham, Jason M. and Tirado-Acevedo, Oscar and Chinn, Mari S. and Pawlak, Joel J. and Grunden, Amy M.}, editor={Parales, R. E.Editor}, year={2015}, month={Oct}, pages={8379–8391} }
 @article{peresin_vesterinen_habibi_johansson_pawlak_nevzorov_rojas_2014, title={Crosslinked PVA nanofibers reinforced with cellulose nanocrystals: Water interactions and thermomechanical properties}, volume={131}, ISSN={0021-8995}, url={http://dx.doi.org/10.1002/APP.40334}, DOI={10.1002/app.40334}, abstractNote={Acid-catalyzed vapor phase esterification with maleic anhydride was used to improve the integrity and thermo-mechanical properties of fiber webs based on poly(vinyl alcohol), PVA. The fibers were produced by electrospinning PVA from aqueous dispersions containing cellulose nanocrystals (CNCs). The effect of esterification and CNC loading on the structure and solvent resistance of the electrospun fibers was investigated. Chemical characterization of the fibers (FTIR, NMR) indicated the formation of ester bonds between hydroxyl groups belonging to neighboring molecules. Thermomechanical properties after chemical modification were analyzed using thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. An 80% improvement in the ultimate strength was achieved for CNC-loaded, crosslinked PVA fiber webs measured at 90% air relative humidity. Besides the ultra-high surface area, the composite PVA fiber webs were water resistant and presented excellent mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40334.}, number={11}, journal={Journal of Applied Polymer Science}, publisher={Wiley}, author={Peresin, Maria Soledad and Vesterinen, Arja-Helena and Habibi, Youssef and Johansson, Leena-Sisko and Pawlak, Joel J. and Nevzorov, Alexander A. and Rojas, Orlando J.}, year={2014}, month={Jan}, pages={n/a-n/a} }
 @article{mathews_pawlak_grunden_2014, title={Isolation of Paenibacillus glucanolyticus from pulp mill sources with potential to deconstruct pulping waste}, volume={164}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2014.04.093}, abstractNote={Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. A microorganism was isolated from a black liquor sample collected from the Department of Forest Biomaterials at North Carolina State University. The organism was identified as Paenibacillus glucanolyticus using 16S rRNA sequence analysis and was shown to be capable of growth on black liquor as the sole carbon source based on minimal media growth studies. Minimal media growth curves demonstrated that this facultative anaerobic microorganism can degrade black liquor as well as cellulose, hemicellulose, and lignin. Gas chromatography–mass spectrometry was used to identify products generated by P. glucanolyticus when it was grown anaerobically on black liquor. Fermentation products which could be converted into high-value chemicals such as succinic, propanoic, lactic, and malonic acids were detected.}, journal={BIORESOURCE TECHNOLOGY}, author={Mathews, Stephanie L. and Pawlak, Joel J. and Grunden, Amy M.}, year={2014}, month={Jul}, pages={100–105} }
 @article{ernest-saunders_pawlak_lee_2014, title={Properties of surface acetylated microfibrillated cellulose relative to intra- and inter-fibril bonding}, volume={21}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-014-0177-7}, number={3}, journal={CELLULOSE}, author={Ernest-Saunders, Rachel and Pawlak, Joel J. and Lee, Jung Myoung}, year={2014}, month={Jun}, pages={1541–1552} }
 @article{ayoub_venditti_pawlak_sadeghifar_salam_2013, title={Development of an acetylation reaction of switchgrass hemicellulose in ionic liquid without catalyst}, volume={44}, ISSN={0926-6690}, url={http://dx.doi.org/10.1016/j.indcrop.2012.10.036}, DOI={10.1016/j.indcrop.2012.10.036}, abstractNote={Hemicellulose material is an abundant and relatively under-utilized hetero-polysaccharides material present in lignocellulosic materials. In this research, an alkaline treatment was applied to switchgrass in order to extract hemicelluloses to subsequently produce an acetylated product. An extraction at 75 °C recovered 27% of the biomass as a predominantly hemicellulose material with a number average degree of polymerization of ∼500 determined by gel permeation chromatography. These hemicelluloses were acetylated with acetic anhydride in 1-allyl-3-methylimidazolium chloride ([Amim]+Cl−) ionic liquid in a complete homogeneous procedure without catalyst for the first time. It was determined that the yield and degree of substitution increased with reaction temperature from 30 to 80 °C and reaction time from 1 to 20 h. The product was characterized by FTIR spectroscopy, NMR, gel permeation chromatography for molecular weight and water contact angle analysis. FTIR spectroscopic analysis showed that the characteristic absorption intensities of acetylated hemicellulose increased and the hydroxyl group decreased with the increase in the degree of substitution. Increased degree of substitution increased the water contact angle and thermal stability in nitrogen. It was possible to cast films of the acetylated hemicellulose although the films were brittle. The results obtained indicate a promising combination between the effective extraction of hemicellulose from grasses and an environmentally friendly process using acetic anhydride in an ionic liquid without a catalyst to generate hemicellulose acetate with high degree of polymerization for use in various industrial applications.}, journal={Industrial Crops and Products}, publisher={Elsevier BV}, author={Ayoub, Ali and Venditti, Richard A. and Pawlak, Joel J. and Sadeghifar, Hasan and Salam, Abdus}, year={2013}, month={Jan}, pages={306–314} }
 @article{hubbe_ayoub_daystar_venditti_pawlak_2013, title={Enhanced absorbent products incorporating cellulose and its derivatives: A review}, volume={8}, DOI={10.15376/biores.8.4.6556-6629}, abstractNote={Cellulose and some cellulose derivatives can play vital roles in the enhancement of the performance of absorbent products. Cellulose itself, in the form of cellulosic fibers or nano-fibers, can provide structure, bulk, water-holding capacity, and channeling of fluids over a wide dimensional range. Likewise, cellulose derivatives such as carboxymethylcellulose (CMC) have been widely studied as components in superabsorbent polymer (SAP) formulations. The present review focuses on strategies and mechanisms in which inclusion of cellulose – in its various forms – can enhance either the capacity or the rate of aqueous fluid absorption in various potential applications.}, number={4}, journal={BioResources}, author={Hubbe, M. A. and Ayoub, A. and Daystar, J. S. and Venditti, R. A. and Pawlak, J. J.}, year={2013}, pages={6556–6629} }
 @article{ayoub_venditti_pawlak_salam_hubbe_2013, title={Novel Hemicellulose–Chitosan Biosorbent for Water Desalination and Heavy Metal Removal}, volume={1}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/sc300166m}, DOI={10.1021/sc300166m}, abstractNote={Hemicellulose material is an abundant and relatively under-utilized polymeric material present in lignocellulosic materials. In this research, an alkaline treatment was applied to pinewood (PW), switchgrass (SG), and coastal bermuda grass (CBG) in order to extract hemicelluloses to subsequently produce a novel biosorbent. Alkaline extraction at 75 °C recovered 23% of the biomass as a predominantly hemicellulose material with a number average degree of polymerization of ∼450. These hemicelluloses were grafted with penetic acid (diethylene triamine pentaacetic acid, DTPA) and were then cross-linked to chitosan. The effects of hemicellulose–DTPA concentration, reaction time, and temperature of reaction with chitosan on the resulting salt (sodium chloride, NaCl) uptake and weight loss in saline solutions were determined. A maximum salt uptake for the materials was ∼0.30 g/g of foam biosorbent. The foam biosorbent was characterized by FT-IR spectra, porosity, and dynamic mechanical analysis. Batch adsorption equilibrium results suggest that the adsorption process for salt follows a second-order kinetic model. The hemicellulose-DTPA-chitosan foam biosorbent had uptakes of 2.90, 0.95, and 1.37 mg/g of Pb2+, Cu2+, and Ni2+ ions, respectively, from aqueous medium at initial concentrations of 5000 PPB at pH 5. The cross-linked hemicellulose–DTPA–chitosan material has good potential for environmental engineering applications.}, number={9}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Ayoub, Ali and Venditti, Richard A. and Pawlak, Joel J. and Salam, Abdus and Hubbe, Martin A.}, year={2013}, month={Jul}, pages={1102–1109} }
 @article{ayoub_venditti_pawlak_massardier_2012, title={Combined Application of Extrusion and Irradiation Technologies: A Strategy Oriented for Green and Cost-Effective Chemistry}, volume={8}, ISSN={1930-2126}, url={http://dx.doi.org/10.15376/biores.8.1.3-5}, DOI={10.15376/biores.8.1.3-5}, abstractNote={Reactive extrusion is an attractive green route for cost-effective polymer processing, which has the potential to enhance the commercial viability of biomass-derived materials. In reactive extrusion, compatibilizers can be generated in the blend preparation through polymer-polymer grafting reactions using functionalized polymers. One very interesting new green strategy for processing is the use of intense UV-irradiation to create free radicals and controllable, ultra-fast reactions. It is reasonable to expect that the use of extrusion/irradiation green technology will be an important way to improve properties and compatibility of renewable biomass- derived polymers. We believe that in the future, many more cost-effective, sustainable extrusion/irradiation reaction processes will be developed to replace inefficient conventional biomass conversion procedures and stimulate the bioproduct-based industry.}, number={1}, journal={BioResources}, publisher={BioResources}, author={Ayoub, Ali and Venditti, Richard A. and Pawlak, Joel J. and Massardier, Valerie}, year={2012}, month={Nov}, pages={3–5} }
 @article{lee_pawlak_heitmann_2012, title={Dimensional and hygroexpansive behaviors of cellulose microfi brils (MFs) from kraft pulp-based fibers as a function of relative humidity}, volume={66}, ISSN={["1437-434X"]}, DOI={10.1515/hf-2011-0129}, abstractNote={Abstract Cellulose aggregate fibrils (CAFs) with dimensions of 100,000×3000×300 nm from unbleached kraft pulp (KP), oxygen delignified KP (KP ox.del ), and fully bleached kraft pulp (BKP) were liberated by a series of high shear and fractionation operations. The CAFs served as microfibril model material to evaluate their dimensional and hygroexpansive behaviors when submitted to variable relative humidities (RHs). The atomic force microscopy images of CAFs from different sources of kraft fibers were obtained during a RH cycle from 50% RH to 78% RH and then to 21% RH while being kept at 23°C. The resulting images were analyzed to determine dimensional changes in length, its concurrent cross-sectional area, width, and height. The mean value of changes in length and width was in the range of 2.3–3.2% and 1.9–3.3%, respectively. The changes in area and height were in the range of 14.5–18.2% and 12.4–17.3%, respectively. The length of CAFs showed a negative correlation with RH, whereas cross-sectional area, width, and height changes correlated positively with RHs. In the out-of-plane direction, such as area and height, the hygroexpansivity was one order of magnitude larger than the in-plane hygroexpansivity, i.e., in terms of length and width.}, number={8}, journal={HOLZFORSCHUNG}, author={Lee, Jung Myoung and Pawlak, Joel J. and Heitmann, John A.}, year={2012}, month={Dec}, pages={1001–1008} }
 @inproceedings{salam_venditti_pawlak_el-tahlawy_ayoub_2012, title={Extraction and utilization of hemicelluloses for new biomaterial applications}, booktitle={Proceeding of the 4th International Conference on Pulping, Papermaking and Biotechnology (ICPPB '12), vols. I and II}, author={Salam, A. and Venditti, R. A. and Pawlak, J. J. and El-tahlawy, K. and Ayoub, A.}, year={2012}, pages={885–890} }
 @article{csoka_hoeger_rojas_peszlen_pawlak_peralta_2012, title={Piezoelectric Effect of Cellulose Nanocrystals Thin Films}, volume={1}, ISSN={2161-1653 2161-1653}, url={http://dx.doi.org/10.1021/mz300234a}, DOI={10.1021/mz300234a}, abstractNote={Ultrathin films of aligned cellulose nanocrystals (CNCs) were assembled on mica supports by using electric field-assisted shear. The relationship between polarization gradients and strain mechanics of the obtained films was examined by monitoring their deflection with an atomic force microscope operated in contact mode. The piezoelectric response of the films was ascribed to the collective contribution of the asymmetric crystalline structure of the cellulose crystals. The magnitude of the effective shear piezoelectric constant (d25) of highly ordered CNC films was determined to be 2.1 Å/V, which is comparable to that of a reference film of a piezoelectric metal oxide.}, number={7}, journal={ACS Macro Letters}, publisher={American Chemical Society (ACS)}, author={Csoka, Levente and Hoeger, Ingrid C. and Rojas, Orlando J. and Peszlen, Ilona and Pawlak, Joel J. and Peralta, Perry N.}, year={2012}, month={Jun}, pages={867–870} }
 @article{jin_lucia_rojas_hubbe_pawlak_2012, title={Survey of Soy Protein Flour as a Novel Dry Strength Agent for Papermaking Furnishes}, volume={60}, ISSN={["1520-5118"]}, DOI={10.1021/jf303023j}, abstractNote={A series of experiments were conducted on recycled pulp samples for the novel purpose of determining the efficacy of employing soy protein flour to increase the strength of dry paper. Values of short span compression and tensile strength were the prime criteria for comparison based on industrial considerations. Various conditions were considered to uncover effective schemes for applying the soy proteins under industrial-like papermaking conditions including alkaline versus acidic as well as high or low ionic content papermaking conditions. A hybrid system of starch, a dry strength additive currently used in paper furnishes, and soy protein was considered to study the possible existence of any synergistic chemical effects. Results indicated that a 1 part (by mass) soy protein to 3 parts cationic starch hybrid system resulted in the highest strength increase in comparison to solely either the soy protein or the cationic starch as dry strength additives.}, number={39}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Jin, Haoyu and Lucia, Lucian A. and Rojas, Orlando J. and Hubbe, Martin A. and Pawlak, Joel J.}, year={2012}, month={Oct}, pages={9828–9833} }
 @article{spence_venditti_rojas_habibi_pawlak_2011, title={A comparative study of energy consumption and physical properties of microfibrillated cellulose produced by different processing methods}, volume={18}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-011-9533-z}, DOI={10.1007/s10570-011-9533-z}, number={4}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Spence, Kelley L. and Venditti, Richard A. and Rojas, Orlando J. and Habibi, Youssef and Pawlak, Joel J.}, year={2011}, month={Apr}, pages={1097–1111} }
 @article{salam_venditti_pawlak_el-tahlawy_2011, title={Crosslinked hemicellulose citrate–chitosan aerogel foams}, volume={84}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/j.carbpol.2011.01.008}, DOI={10.1016/j.carbpol.2011.01.008}, abstractNote={The applications for hemicellulose are currently very narrow, because of its low molecular weight and varying chemical composition. In this research, novel applications for modified hemicellulose are developed making it a valuable biomaterial for absorbency applications in health care and medical textiles. The incorporation of carboxylic acid groups into hemicellulose via reaction with citric acid followed by cross linking with chitosan greatly improve the properties relative to hemicellulose, chitosan, a cellulose sponge product, and hemicellulose citrate alone. Optimum conditions for the cross linking of the hemicellulose citrate–chitosan include a 2.5 h reaction time at 110 °C with pH 3.5, a solid to liquid ratio of 1:100 and a hemicellulose citrate to chitosan ratio of 1:1 (w/w). The hemicellulose citrate–chitosan crosslinked foam is elastic, very soft, highly porous and durable. The hemicellulose citrate–chitosan can absorb up to 100 g of a saline solution per gram of material and up to 80 g of water per gram of material. Analysis of the hemicellulose citrate–chitosan foams with FTIR, DMA, and SEM confirms the crosslinked and hygroscopic behavior of the materials.}, number={4}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={Salam, Abdus and Venditti, Richard A. and Pawlak, Joel J. and El-Tahlawy, Khaled}, year={2011}, month={Apr}, pages={1221–1229} }
 @article{salam_pawlak_venditti_el-tahlawy_2011, title={Incorporation of carboxyl groups into xylan for improved absorbency}, volume={18}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-011-9542-y}, number={4}, journal={CELLULOSE}, author={Salam, Abdus and Pawlak, Joel J. and Venditti, Richard A. and El-tahlawy, Khaled}, year={2011}, month={Aug}, pages={1033–1041} }
 @article{spence_venditti_rojas_pawlak_hubbe_2011, title={Water vapor barrier properties of coated and filled microfibrillated cellulose composite films}, volume={6}, DOI={10.15376/biores.6.4.4370-4388}, abstractNote={Microfibrillated celluloses (MFCs) have mechanical properties sufficient for packaging applications, but lack in comparison to petroleum-based plastics in water vapor barrier properties. These properties can be modified by the use of mineral fillers, added within the film structure, or waxes, as surface coatings. In this investigation it was found that addition of fillers resulted in films with lower densities but also lower water vapor transmission rates. This was hypothesized to be due to decreased water vapor solubility in the films. Associated transport phenomena were described by the Knudsen model for diffusion but due to the limited incorporation of chemical factors in the model, accurate prediction of pore diameters for filled films was not possible. Modeling the filled-films with Fick’s equation, however, takes into account chemical differences, as observed by the calculated tortuosity values. Remarkably, coating with beeswax, paraffin, and cooked starch resulted in films with water vapor transmission rates lower than those for low density polyethylene. These coatings were modeled with a three-layer model which determined that coatings were more effective in reducing WVTR.}, number={4}, journal={BioResources}, author={Spence, K. L. and Venditti, R. A. and Rojas, O. J. and Pawlak, J. J. and Hubbe, M. A.}, year={2011}, pages={4370–4388} }
 @article{patel_venditti_pawlak_2010, title={Dimensional changes of starch microcellular foam during the exchange of water with ethanol and subsequent drying}, volume={5}, number={1}, journal={BioResources}, author={Patel, S. V. and Venditti, R. A. and Pawlak, J. J.}, year={2010}, pages={121–134} }
 @article{peresin_habibi_vesterinen_rojas_pawlak_seppala_2010, title={Effect of Moisture on Electrospun Nanofiber Composites of Poly(vinyl alcohol) and Cellulose Nanocrystals}, volume={11}, ISSN={["1526-4602"]}, DOI={10.1021/bm1006689}, abstractNote={The effect of humidity on the morphological and thermomechanical properties of electrospun poly(vinyl alcohol) (PVA) fiber mats reinforced with cellulose nanocrystals (CNs) was investigated. Scanning electron microscopy (SEM) images revealed that the incorporation of CNs improved the morphological stability of the composite fibers even in high humidity environments. Thermal and mechanical properties of the electrospun fiber mats were studied by using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and large deformation tensile tests under controlled humidity and temperatures. The balance between the moisture-induced plasticization and the reinforcing effect of rigid CN particles was critical in determining the thermomechanical behaviors of the electrospun fiber mats. Results indicated that the stabilizing effect of the CNs in the PVA matrix might be compromised by water absorption, disrupting the hydrogen bonding within the structure. The amount of this disruption depended on the surrounding humidity and the CN loading. The reduction in tensile strength of neat PVA fiber mats as they were conditioned from low relative humidity (10% RH) to high relative humidity (70% RH) was found to be about 80%, from 1.5 to 0.4 MPa. When the structure was reinforced with CNs, the reduction in strength was limited to 40%, from 2 to 0.8 MPa over the same range in relative humidity. More importantly, the CN-loaded PVA fiber mats showed a reversible recovery in mechanical strength after cycling the relative humidity. Finally, humidity treatments of the composite PVA fiber mats induced significant enhancement of their strength as a result of the adhesion between the continuous matrix and the CNs.}, number={9}, journal={BIOMACROMOLECULES}, author={Peresin, Maria S. and Habibi, Youssef and Vesterinen, Arja-Helena and Rojas, Orlando J. and Pawlak, Joel J. and Seppala, Jukka V.}, year={2010}, month={Sep}, pages={2471–2477} }
 @article{lee_pawlak_heitmann_2010, title={Longitudinal and concurrent dimensional changes of cellulose aggregate fibrils during sorption stages}, volume={61}, ISSN={["1873-4189"]}, DOI={10.1016/j.matchar.2010.02.007}, abstractNote={Atomic force microscopy (AFM) studies of the dimensional changes of cellulose microfibril materials, called cellulose aggregate fibrils (approx. 100 µm × 3 µm × 300 nm), exposed to two distinct relative humidities of 80% and 23% for 24 h and then suddenly subjected to 50% RH and 23 °C show that the fibrils are responsive to the surrounding environments in a nonspecific fashion. AFM images (10 µm × 10 µm) of the individual straight cellulose aggregate fibrils were taken as a function of elapsed time during both desorption and adsorption of moisture. The longitudinal distance between discrete natural defects observed on the cellulose aggregate fibrils as well as the width, cross-sectional area, and height of the cellulose aggregate fibril were measured from the AFM images. The length of the cellulose aggregate fibrils was found to have reduced after exposure to either high or low relative humidity, and then placement in ambient conditions. Over time in ambient conditions, the cellulose aggregate fibrils progressively relaxed to their original length during both desorption and adsorption of moisture. However, the relaxation rate during adsorption was faster than that during desorption. The possible explanations for this phenomenon are discussed including the sample preparation method, volume conservation, entropy elasticity, and free volume theory. The changes in the width, height, and cross-sectional area are also discussed.}, number={5}, journal={MATERIALS CHARACTERIZATION}, author={Lee, Jung Myoung and Pawlak, Joel J. and Heitmann, John A.}, year={2010}, month={May}, pages={507–517} }
 @article{hu_heitmann_rojas_pawlak_argyropoulos_2010, title={Monitoring Cellulase Protein Adsorption and Recovery Using SDS-PAGE}, volume={49}, ISSN={0888-5885 1520-5045}, url={http://dx.doi.org/10.1021/ie100731b}, DOI={10.1021/ie100731b}, abstractNote={Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was employed to study the sorption behaviors of cellulases on microcrystalline celluloses and hardwood pulp. The adsorption and recovery of cellulases from Aspergillus niger and Trichoderma reesei were investigated at 25 °C. Cellulase recovery was conducted by rinsing adsorbed enzymes with sodium acetate buffer, Milli-Q water, and sodium hydroxide solution. The initial, equilibrium, and recovered enzymes were analyzed using SDS-PAGE gels. Gels were scanned and analyzed using ImagePro software. The molecular weights of cellulase proteins were determined using a protein marker having seven known proteins. The cellulase system from Trichoderma reesei had a higher adsorption on all substrates studied than the cellulase system from Aspergillius niger, and higher pH favored desorption from the substrates studied. Experimental results also demonstrated that adsorption and desorption amounts determined by SDS-PAGE were proportional to protein concentrations in their crude mixtures.}, number={18}, journal={Industrial & Engineering Chemistry Research}, publisher={American Chemical Society (ACS)}, author={Hu, Gang and Heitmann, John A., Jr. and Rojas, Orlando J. and Pawlak, Joel J. and Argyropoulos, Dimitris S.}, year={2010}, month={Sep}, pages={8333–8338} }
 @article{peresin_habibi_zoppe_pawlak_rojas_2010, title={Nanofiber Composites of Polyvinyl Alcohol and Cellulose Nanocrystals: Manufacture and Characterization}, volume={11}, ISSN={["1526-4602"]}, DOI={10.1021/bm901254n}, abstractNote={Cellulose nanocrystals (CN) were used to reinforce nanofibers in composite mats produced via electrospinning of poly(vinyl alcohol) (PVA) with two different concentrations of acetyl groups. Ultrathin cross-sections of the obtained nanocomposites consisted of fibers with maximum diameters of about 290 nm for all the CN loads investigated (from 0 to 15% CN loading). The electrospinning process did not affect the structure of the PVA polymer matrix, but its degree of crystallinity increased significantly together with a slight increase in the corresponding melting temperature. These effects were explained as being the result of alignment and enhanced crystallization of PVA chains within the individual nanofibers that were subjected to high shear stresses during electrospinning. The strong interaction of the PVA matrix with the dispersed CN phase, mainly via hydrogen bonding or bond network, was reduced with the presence of acetyl groups in PVA. Most importantly, the elastic modulus of the nanocomposite mats increased significantly as a consequence of the reinforcing effect of CNs via the percolation network held by hydrogen bonds. However, this organization-driven crystallization was limited as observed by the reduction in the degree of crystallinity of the CN-loaded composite fibers. Finally, efficient stress transfer and strong interactions were demonstrated to occur between the reinforcing CN and the fully hydrolyzed PVA electrospun fibers.}, number={3}, journal={BIOMACROMOLECULES}, author={Peresin, Maria S. and Habibi, Youssef and Zoppe, Justin O. and Pawlak, Joel J. and Rojas, Orlando J.}, year={2010}, month={Mar}, pages={674–681} }
 @article{salam_pawlak_venditti_el-tahlawy_2010, title={Synthesis and Characterization of Starch Citrate−Chitosan Foam with Superior Water and Saline Absorbance Properties}, volume={11}, ISSN={1525-7797 1526-4602}, url={http://dx.doi.org/10.1021/bm1000235}, DOI={10.1021/bm1000235}, abstractNote={The objective of this research was to synthesize and characterize high-value foam gel materials with unique absorptive and mechanical properties from starch citrate−chitosan. The effects of starch citrate concentration, pH, solid to liquid ratio, reaction time, and temperature on absorbency, weight loss in water, and strength were determined. The cross-linked starch citrate−chitosan foam is flexible and elastic and has significantly increased absorbance and strength and decreased weight loss in water compared to starch-chitosan foam. A unique characteristic of the starch citrate-chitosan foam is that it absorbs more saline solution than pure water, which is the opposite of current commercial super absorbents. An increased strength, increased degradation temperature, increased storage modulus, and decreased weight loss in water for starch citrate−chitosan relative to starch−chitosan are in agreement with amide bonds formed between the carboxyl group of starch citrate and the amino group of chitosan.}, number={6}, journal={Biomacromolecules}, publisher={American Chemical Society (ACS)}, author={Salam, Abdus and Pawlak, Joel J. and Venditti, Richard A. and El-tahlawy, Khaled}, year={2010}, month={May}, pages={1453–1459} }
 @article{spence_venditti_habibi_rojas_pawlak_2010, title={The effect of chemical composition on microfibrillar cellulose films from wood pulps: Mechanical processing and physical properties}, volume={101}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/j.biortech.2010.02.104}, DOI={10.1016/j.biortech.2010.02.104}, abstractNote={Films of microfibrillated celluloses (MFCs) from pulps of different yields, containing varying amounts of extractives, lignin, and hemicelluloses, were produced by combining refining and high-pressure homogenization techniques. MFC films were produced using a casting-evaporation technique and the physical and mechanical properties (including density, roughness, fold endurance and tensile properties) were determined. Homogenization of bleached and unbleached Kraft pulps gave rise to highly individualized MFCs, but not for thermo-mechanical pulp (TMP). The resulting MFC films had a roughness equivalent to the surface upon which the films were cast. Interestingly, after homogenization, the presence of lignin significantly increased film toughness, tensile index, and elastic modulus. The hornification of fibers through a drying and rewetting cycle prior to refining and homogenization did not produce any significant effect compared to films from never-dried fibers, indicating that MFC films can potentially be made from low-cost recycled cellulosic materials.}, number={15}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Spence, Kelley L. and Venditti, Richard A. and Habibi, Youssef and Rojas, Orlando J. and Pawlak, Joel J.}, year={2010}, month={Aug}, pages={5961–5968} }
 @article{spence_venditti_rojas_habibi_pawlak_2010, title={The effect of chemical composition on microfibrillar cellulose films from wood pulps: water interactions and physical properties for packaging applications}, volume={17}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-010-9424-8}, DOI={10.1007/s10570-010-9424-8}, number={4}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Spence, Kelley L. and Venditti, Richard A. and Rojas, Orlando J. and Habibi, Youssef and Pawlak, Joel J.}, year={2010}, month={May}, pages={835–848} }
 @article{patel_venditti_pawlak_ayoub_rizvi_2009, title={Development of Cross-Linked Starch Microcellular Foam by Solvent Exchange and Reactive Supercritical Fluid Extrusion}, volume={111}, ISSN={["1097-4628"]}, DOI={10.1002/app.29270}, abstractNote={Starch microcellular foams (SMCFs) are prepared by pore preserving drying or formation processes and contain pores in the micron size range. SMCFs have high specific surface area and are useful for applications such as opacifying pigments or as adsorbent materials. The objective of this research was to determine how the processing conditions and use of a crosslinking agent would affect the foam structure and properties. SMCFs (crosslinked and uncrosslinked) were prepared from molded aquagels and carbon dioxide extrusion processes separately and then solvent exchanged. Extruded samples showed macroscopic pores whereas samples from aquagels showed a much finer micropore structure. Aquagel-based SMCF samples had lower density and higher brightness than did extruded samples. The starch foams with micropore structure had low density and high brightness. The solvent exchange process was the most important variable in generating a microcellular structure. Micropores and not macropores contributed to increased brightness of these materials. The brightness and density of the foams were found to be linearly related. Crosslinking with epichlorohydrin imparted significant water resistance to the extruded samples as evidenced in lower water swelling and higher contact angles. Equilibrium moisture content was correlated with the microporous structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009}, number={6}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, publisher={Wiley}, author={Patel, Sarneerkumar and Venditti, Richard A. and Pawlak, Joel J. and Ayoub, Ali and Rizvi, Syed S. H.}, year={2009}, month={Mar}, pages={2917–2929} }
 @article{bastidas_pawlak_venditti_heitmann_hubbe_kadla_2008, title={A colloidal probe microscopy study of cellulose/gypsum interactions}, volume={59}, ISSN={["1044-5803"]}, DOI={10.1016/j.matchar.2006.12.007}, abstractNote={Drywall, which is made primarily of a calcium sulfate dihydrate (gypsum) core with paper on both sides, is one of the most widely used construction materials. Because board failure often occurs at the gypsum core/paper interface, it has become important to know the exact nature of the gypsum/cellulose bond and how crystal morphology affects it. This study provides data about the nature of this interaction by means of AFM and Colloidal Probe Microscopy. These methods made it possible to distinguish among the different crystal faces and their respective interactions with cellulose. Measured in air, the adhesive forces between the AFM tip and the different faces varied according to f(010) < f(120) < f(111) at 50% relative humidity. The differences in adhesive force with the different gypsum crystals face can be attributed to the differences in surface chemistry. The information obtained in this study will help guide improvements in the gypsum wallboard production process to obtain better bonding between the crystal and the paper.}, number={2}, journal={MATERIALS CHARACTERIZATION}, author={Bastidas, Juan C. and Pawlak, Joel J. and Venditti, Richard A. and Heitmann, John A. and Hubbe, Martin A. and Kadla, John F.}, year={2008}, month={Feb}, pages={144–150} }
 @article{pawlak_2008, title={A sustainable economy}, volume={3}, number={1}, journal={BioResources}, author={Pawlak, J. J.}, year={2008}, pages={1–2} }
 @article{rutledge_venditti_pawlak_patel_cibils_2008, title={Carbonized starch microcellular foam-cellulose fiber composite structures}, volume={3}, number={4}, journal={BioResources}, author={Rutledge, A. R. and Venditti, R. A. and Pawlak, J. J. and Patel, S. and Cibils, J. L.}, year={2008}, pages={1063–1080} }
 @article{el-tahlawy_venditti_pawlak_2008, title={Effect of alkyl ketene dimer reacted starch on the properties of starch microcellular foam using a solvent exchange technique}, volume={73}, ISSN={["0144-8617"]}, DOI={10.1016/j.carbpol.2007.11.013}, abstractNote={The production of a hydrophobic starch microcellular foam (SMCF) through the addition of an alkyl ketene dimer (AKD) would be a bio-based material with valuable properties for many applications in which high specific surface area, low density and water resistance is important. Pigments for paper and coatings are a potential application. An emulsion of AKD and cooked corn starch was made by mixing AKD with cooked starch at 50 °C under a high rate of shear. The effects of reaction temperature, starch concentration and pH on the reaction of AKD with starch and the resulting microcellular foam structure were studied. The starch/AKD foam particles were characterized by scanning electron microscope (SEM), elemental analysis to determine extent of reaction, thermogravimetric analysis (TGA), brightness, particle size and water swellability. The apparent viscosity of the starch solution was shown to have a linear relationship with the particle size and the brightness of the particles. The particles under all conditions had a very high brightness. The AKD was able to impart a significant hydrophobicity to the particles relative to starch alone but the water resistance was not great enough to preserve the porous structure when wetted.}, number={1}, journal={CARBOHYDRATE POLYMERS}, author={El-Tahlawy, Khaled and Venditti, Richard and Pawlak, Joel}, year={2008}, month={Jul}, pages={133–142} }
 @article{el-tahlawy_venditti_pawlak_2007, title={Aspects of the preparation of starch microcellular foam particles crosslinked with glutaraldehyde using a solvent exchange technique}, volume={67}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/j.carbpol.2006.05.029}, DOI={10.1016/j.carbpol.2006.05.029}, abstractNote={Starch microcellular foam (SMCF) has been produced using a solvent exchange technique with a native corn starch crosslinked with glutaraldehyde. To produce a high specific surface area for the starch particles the cooked starch solution was reacted with glutaraldehyde and then precipitated under shear with ethanol. The relationship between the crosslinking density on the void structure of the SMCF has been studied. Characterization by NMR confirmed the crosslinking reaction. An increase in the glutaraldehyde concentration from 0 to 15 g glutaraldehyde/100 g starch was accompanied by a decrease in particle size and moisture content and an increase in brightness and specific surface area. Scanning electron microscope images of the SMCF particles show that the smallest average void diameter obtained was 0.182 μm at a 7.5 g glutaraldehyde/100 g starch. Four starch materials having different viscosity were prepared by hydrolysis of the native corn starch with a 1 N HCl/methanol system for different reaction durations to investigate the relationship between starch molecular weight and void structure of the SMCF. The starches were crosslinked with 15 g glutaraldehyde/100 g starch and precipitated with ethanol to form SMCF. Decreasing the starch viscosity decreased the brightness and specific surface area, and increased the particle size, void diameter and moisture content. Increases in stirring speed during the precipitation enhanced the properties of the SMCF particles. The effect of pressing the starch particles to form a pellet caused a collapse of the foam structure at pressures above about 6000 psi. The results indicate that the structure/chemistry of the starch material and the processing conditions can be controlled in order to produce particles with morphology and properties useful for light scattering applications. In particular, higher molecular weight and intermolecular crosslinking and high shear during precipitation have been found to enhance the foam formation.}, number={3}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={El-Tahlawy, Khaled and Venditti, Richard A. and Pawlak, Joel J.}, year={2007}, month={Feb}, pages={319–331} }
 @article{bolivar_venditti_pawlak_el-tahlawy_2007, title={Development and characterization of novel starch and alkyl ketene dimer microcellular foam particles}, volume={69}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/j.carbpol.2006.10.004}, DOI={10.1016/j.carbpol.2006.10.004}, abstractNote={There is interest in replacing inorganic fillers in paper, coatings and plastics with renewable organic fillers to improve the economics, performance and environmental aspects of such products. Starch microcellular foam (SMCF) particles are promising materials in this regard. This research was undertaken to produce SMCF particles and characterize their morphology, optical properties and interaction with water. SMCF particles were produced using corn starch; which was solubilized in water. The foam structure was created by precipitating the starch using ethanol in a solvent exchange technique. The starch was also reacted with alkyl ketene dimer (AKD) wax at different levels in order to understand if the AKD could impart water resistance to the particles. Two methods were used to incorporate AKD: (1) the AKD was coated onto foam particles after foam formation, and (2) the AKD was blended with the starch before foam particle formation. Hexane extraction was used to purify a portion of each of the samples to determine if unreacted AKD existed with the starch matrix. Particles with porous structure and high brightness were developed for all combinations of starch and AKD. The brightness of the particles was significantly higher than that of the uncooked starch, presumably due to the development of a porous structure. For the AKD coated particles a minimum amount of AKD charged was needed to develop a high contact angle, low solubility, and low water retention value, higher levels of AKD in AKD coated particles did not further alter these properties. This indicates that the changes in properties with AKD level with coated particles is a surface phenomena. Starch AKD blends did not show any increased resistance to water relative to the particles with no AKD blended. This is due to the ethanol used in the precipitation process extracting the AKD, which was confirmed by elemental analysis. The particles, even with the 10% AKD coated or blended, lost their porous structure upon rewetting. Further work needs to be performed to more effectively hydrophobize the starch foams with AKD.}, number={2}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={Bolivar, Ana I. and Venditti, Richard A. and Pawlak, Joel J. and El-Tahlawy, Khaled}, year={2007}, month={Jun}, pages={262–271} }
 @article{park_venditti_jameel_pawlak_2007, title={Hard-to-remove water in cellulose fibers characterized by thermal analysis: A model for the drying of wood-based fibers}, volume={6}, number={7}, journal={TAPPI Journal}, author={Park, S. and Venditti, R. A. and Jameel, H. and Pawlak, J. J.}, year={2007}, pages={10–16} }
 @article{lee_heitmann_pawlak_2007, title={Local morphological and dimensional changes of enzyme-degraded cellulose materials measured by atomic force microscopy}, volume={14}, ISSN={["0969-0239"]}, DOI={10.1007/s10570-007-9172-6}, number={6}, journal={CELLULOSE}, author={Lee, Jung Myoung and Heitmann, John A. and Pawlak, Joel J.}, year={2007}, month={Dec}, pages={643–653} }
 @article{lee_heitmann_pawlak_2007, title={Rheology of carboxymethyl cellulose solutions treated with cellulases}, volume={2}, number={1}, journal={BioResources}, author={Lee, J. M. and Heitmann, J. A. and Pawlak, J. J.}, year={2007}, pages={20–33} }
 @article{park_venditti_jameel_pawlak_2007, title={Studies of the heat of vaporization of water associated with cellulose fibers characterized by thermal analysis}, volume={14}, ISSN={["0969-0239"]}, DOI={10.1007/s10570-007-9108-1}, number={3}, journal={CELLULOSE}, author={Park, Sunkyu and Venditti, Richard A. and Jameel, Hasan and Pawlak, Joel J.}, year={2007}, month={Jun}, pages={195–204} }
 @article{park_venditti_abrecht_jameel_pawlak_lee_2007, title={Surface and pore structure modification of cellulose fibers through cellulase treatment}, volume={103}, ISSN={["0021-8995"]}, DOI={10.1002/app.25457}, abstractNote={The surface and pore structure of cellulose fibers have a significant impact on the properties and performance in applications. Cellulase enzymatic hydrolysis of cellulose fibers can result in changes to the surface and pore structure, thus providing a useful tool for fiber modification. This research characterizes these changes using various test methods such as fiber dimension, water retention value (WRV), hard-to-remove (HR) water content, freezing and nonfreezing bound water content, polymer adsorption, and crystallinity index. For a high-dosage cellulase treatment (600 U/g dry solid), the fiber length was significantly decreased and the fibers were “cut” in the cross direction, not in the axial direction. The swelling capacities as measured by the WRV and HR water content increased for the high-dosage treatment. Three independent measurements (nonfreezing bound water, polymer adsorption, and crystallinity index) are in good agreement with the statement that the amorphous regions of cellulose fibers are a more readily available substrate relative to crystalline regions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3833–3839, 2007}, number={6}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Park, Sunkyu and Venditti, Richard A. and Abrecht, David G. and Jameel, Hasan and Pawlak, Joel J. and Lee, Jung M.}, year={2007}, month={Mar}, pages={3833–3839} }
 @article{lee_heitmann_pawlak_2007, title={Technique for the measurement of dimensional changes of natural microfibril materials under variable humidity environments}, volume={445}, DOI={10.1016/j.msea.2006.09.096}, abstractNote={Abstract An algorithm was developed to analyze the dimensions of line scan data of step-shaped disconitunities acquired with an atomic force microscope. The effect of a number of AFM parameters on the quantitative imaging of step features was discussed. Quantitiative imaging using AFM was shown to be very reproducible as five successive scans of a standard step height grating produced less than 3% variation in measured parameters. A cellulose microfibril, called cellulose aggregate fibril (CAF), with dimensions of ∼50,000 nm × 2000 nm × 300 nm derived from papermaking fibers was scanned under cyclic relative humdity conditions with the relative humidity starting at 50% then raising to 80% followed by a decrease in the relative humidity to 28%. Changes in the width of the CAF were weakly correlated with changes in the relative humdity, while changes in the height and area of the CAF were positively correlated with the relative humdity. The length of the CAF was negatively correlated with the given relative humdity cycle. These findings have significant implications in paper dimensional stability and the engineering of cellulose micro and nano-fiber composites.}, journal={Materials Science & Engineering. A, Structural Materials: Properties, Microstructure and Processing}, author={Lee, J. M. and Heitmann, J. A. and Pawlak, Joel}, year={2007}, pages={632–640} }
 @article{park_venditti_jameel_pawlak_2006, title={A novel method to evaluate fibre hornification by high resolution thermogravimetric analysis}, volume={59}, number={6}, journal={Appita Journal}, author={Park, S. and Venditti, R. A. and Jameel, H. and Pawlak, J. J.}, year={2006}, pages={481–485} }
 @article{park_venditti_jameel_pawlak_2006, title={Changes in pore size distribution during the drying of cellulose fibers as measured by differential scanning calorimetry}, volume={66}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/j.carbpol.2006.02.026}, DOI={10.1016/j.carbpol.2006.02.026}, abstractNote={Changes in pore size distribution during the drying of cellulose fibers were determined using differential scanning calorimetry (DSC) with an isothermal step melting procedure. Softwood bleached kraft pulp at various moisture ratios were generated from partial drying in a thermogravimetric analyzer and then analyzed in a DSC. The pore size distribution was calculated using the Gibbs–Thomson equation and specific melting point depression of water detected by DSC. It was observed that larger pores collapse first followed by the sequential collapse of smaller pores. It is suggested that pore wall collapse resistance is the primary factor that determines which size pores close. The average measured pore size in the fiber wall of the never dried fiber was calculated to be about 80 nm and reduced with drying of the fibers. A constant pore size of about 20 nm was observed at moisture ratios below 0.3 g/g, which corresponds to one-to-two layers of non-freezing bound water tightly bound to the surface.}, number={1}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={Park, S and Venditti, R and Jameel, H and Pawlak, J}, year={2006}, month={Oct}, pages={97–103} }
 @article{park_venditti_jameel_pawlak_2006, title={Hard to remove water in cellulose fibers characterized by high resolution thermogravimetric analysis - methods development}, volume={13}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-005-9009-0}, DOI={10.1007/s10570-005-9009-0}, number={1}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Park, Sunkyu and Venditti, Richard A. and Jameel, Hasan and Pawlak, Joel J.}, year={2006}, month={Nov}, pages={23–30} }
 @article{bastidas_venditti_pawlak_gilbert_zauscher_kadla_2005, title={Chemical force microscopy of cellulosic fibers}, volume={62}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/j.carbpol.2005.08.058}, DOI={10.1016/j.carbpol.2005.08.058}, abstractNote={Atomic force microscopy with chemically modified cantilever tips (chemical force microscopy) was used to study the pull-off forces (adhesion forces) on cellulose model surfaces and bleached softwood kraft pulp fibers in aqueous media. It was found that for the –COOH terminated tips, the adhesion forces are dependent on pH, whereas for the –CH3 and –OH terminated tips adhesion is not strongly affected by pH. Comparison between the cellulose model surfaces and cellulosic fibers under our experimental conditions reveal that surface roughness does not affect adhesion strongly. X-ray photoelectron spectroscopy (XPS) and Fourier Transformed Infrared (FTIR) spectroscopy reveal that both substrate surfaces have homogeneous chemical composition. The results show that chemical force microscopy can be used for the chemical characterization of cellulose surfaces at a nano-level.}, number={4}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={Bastidas, J and Venditti, R and Pawlak, J and Gilbert, R and Zauscher, S and Kadla, J}, year={2005}, month={Dec}, pages={369–378} }
 @inproceedings{park_venditti_pawlak_jameel_2005, title={High resolution thermo-gravimetric analysis of pulp drying}, booktitle={Advances in Paper Science and Technology: Transactions of the 13th Fundamental research symposium, vols 1-3}, author={Park, S. and Venditti, R. A. and Pawlak, J. J. and Jameel, H.}, year={2005}, pages={161–186} }
 @article{park_venditti_jameel_pawlak_2005, title={The  effect of fibre properties on fibre fractionation using a hydrocyclone}, volume={31}, number={3}, journal={Journal of Pulp and Paper Science}, author={Park, S. and Venditti, R. A. and Jameel, H. and Pawlak, J. J.}, year={2005}, pages={132–137} }
 @article{pawlak_keller_2005, title={The compressive response of a stratified fibrous structure}, volume={37}, ISSN={["0167-6636"]}, DOI={10.1016/j.mechmat.2004.12.002}, abstractNote={Abstract A model for the compressive response of an oriented fiber structure such as paper is derived in this work. The model provides a semi-quantitative description of the stress/strain behavior of a fiber structure. The model accounts for the deformation of fibers during compression, their finite fiber length, their elastic modulus, and their moment of inertia. Using a previously describe micro-indentation technique, the predicted impact of variables used in the model on the compressive response of paper is verified. Results consistent with the model are found including a strong dependence of the tangent modulus on apparent density of the sheet, and a relative insensitivity of the tangent modulus to fiber length. The three stage behavior of the paper compression described by Rodal [Soft-nip calendering of paper and paperboard. Tappi Journal 72 (5), 177–186] was also accounted for in the model.}, number={11}, journal={MECHANICS OF MATERIALS}, author={Pawlak, JJ and Keller, DS}, year={2005}, month={Nov}, pages={1132–1142} }
 @article{pawlak_keller_2004, title={Relationships between the local sheet structure and Z-direction compressive characteristics of paper}, volume={30}, number={9}, journal={Journal of Pulp and Paper Science}, author={Pawlak, J. J. and Keller, D. S.}, year={2004}, pages={256–262} }
 @article{keller_pawlak_kellomaki_haglund_johansson_2004, title={Three storage phosphor systems for beta-radiographic imaging of paper}, volume={19}, ISSN={["0283-2631"]}, DOI={10.3183/npprj-2004-19-02-p170-175}, number={2}, journal={NORDIC PULP & PAPER RESEARCH JOURNAL}, author={Keller, DS and Pawlak, JJ and Kellomaki, M and Haglund, JE and Johansson, N}, year={2004}, pages={170–175} }
 @article{pawlak_keller_2003, title={Measurement of the local compressive characteristics of polymeric film and web structures using micro-indentation}, volume={22}, ISSN={["0142-9418"]}, DOI={10.1016/S0142-9418(02)00146-0}, abstractNote={Abstract The local compressive properties of paper influence its printing, calendering and friction characteristics. A continuous indentation instrument was developed to evaluate the local compressive characteristics of the paper sheet. A description of the instrumentation is presented. A method for determining the area of contact between the probe tip and the material surface from the load vs displacement data is implemented. This method provides a significant experimental simplification when compared to imaging of the individual indentations. A novel data analysis technique was developed to evaluate the continuous indentation data of thin materials. The technique was shown to be valid when the ratio of thickness to contact radius is less than two. This technique was compared with the traditional Hertzian analysis. The compressive elastic characteristics of a variety of films and fibrous webs were determined. The measured values were compared with results obtained from other methods. For paper samples, the ~ 10:1 ratio of the in-plane modulus to out-of-plane modulus observed with sonic measurements was also observed with the continuous indentation.}, number={5}, journal={POLYMER TESTING}, author={Pawlak, JJ and Keller, DS}, year={2003}, month={Aug}, pages={515–528} }
 @article{hubbe_pawlak_koukoulas, title={Paper's appearance: A review}, volume={3}, number={2}, journal={BioResources}, author={Hubbe, M. A. and Pawlak, J. J. and Koukoulas, A. A.}, pages={627–665} }