@misc{v. hamm_kozel_jones_atree_2024, title={Colloid chemical aspects of paper formation in the presence of nanofibrillated cellulose and cationic starch}, volume={23}, ISSN={["0734-1415"]}, DOI={10.32964/TJ23.9.491}, abstractNote={A series of experimental tests were carried out to examine colloidal-scale consequences of optional-ly treating nanofibrillated cellulose (NFC) with cationic starches of different charge density and dosage (0.5% or 2.0% by weight), adding that material to a furnish prepared from 100% recycled copy paper, and then subjecting the mixture to very different levels of hydrodynamic shear. Tests included optical microscopy, sediment volume tests, sediment velocity tests, and “percent fines” assessment by means of a fiber quality analyzer (FQA). In addition, the zeta potential and charge demand of the studied materials were evaluated. Optical imaging revealed that cationic starch treatment of the NFC tended to agglomerate it into multiparticle clusters, which sometimes could be mostly redispersed by hydrodynamic shear. Subsequent addition of the starch-treated NFC to the default furnish resulted in much of the colloidal material becoming attached to fibers. Subsequent shearing of the mixtures was at least partly effective in separating the clusters of NFC from the fiber surface, resulting in essentially a two-component mixture. Multiparticle NFC clusters coexisted with the fiber suspension, sometimes attached and sometimes not, depending on the details of treatments. Sediment volume tests showed that systems containing cationic starch-treated NFC tended to have a higher density after settling in comparison to untreated NFC; these findings are consistent with the cationic starch acting as a stabilizer on the solid surfaces, allowing them to slide past each other during the settling process. Application of intense hydrodynamic shear tended to result in denser sediment. Results of tests with the sediment velocity measurement and the FQA percent fines assessment did not correlate well with changes in test conditions considered in this study.}, number={9}, journal={TAPPI JOURNAL}, author={V. Hamm, Kensley and Kozel, Daniel J. and Jones, Lucy A. and Atree, Varun S.}, year={2024}, month={Sep} }
 @article{hamm_kozel_jones_atree_ryu_hubbe_2024, title={Effects of hydrodynamic shear during formation of paper sheets with the addition of nanofibrillated cellulose, cationic starch, and cationic retention aid}, volume={23}, ISSN={["0734-1415"]}, DOI={10.32964/TJ23.9.477}, abstractNote={Laboratory tests were conducted to evaluate effects of hydrodynamic shear levels on papermaking process variables and paper handsheet properties. The furnish was from 100% recycled copy paper, to which was added nanofibrillated cellulose (NFC) at the 5% level following its optional pretreatment with cationic starch. A cationic copolymer of acrylamide (cPAM) was used as the retention aid. Different levels of hydrodynamic shear were applied both after mixing the NFC with the cationic starch (pre-shearing) or after all the furnish components had been combined (final shearing). The presence or absence of pre-shearing was found to have little effect on the measured outcomes. By contrast, increasing final shear hurt filler retention and made the resulting paper more uniform. However, the final shear level did not have a significant effect on the tensile strength of the resulting handsheets. Medium-charge density cationic starch, used in pretreating the NFC, consistently gave greater strength in comparison to a high-charge cationic starch. The significance of these findings is that though the relatively high hydrodynamic shear levels associated with modern paper machines can have some beneficial effects, they do not necessarily overcome all challenges associated with wet-end addition of nanocellulose in combination with other additives.}, number={9}, journal={TAPPI JOURNAL}, author={Hamm, Kensley V and Kozel, Daniel J. and Jones, Lucy A. and Atree, Varun S. and Ryu, Jeong-Yong and Hubbe, Martin A.}, year={2024}, month={Sep}, pages={477–490} }