@article{najafi_kotek_2019, title={Mechanical properties of PTT fibers by sustainable horizontal isothermal bath process}, volume={1}, ISSN={["2523-3971"]}, DOI={10.1007/s42452-019-1198-5}, abstractNote={The melt spinning process of poly (trimethylene terephthalate) was modified by the inclusion of horizontal isothermal bath (HIB) in the extrusion line. Several parameters including liquid depth, liquid temperature, and take-up speed were utilized in this study. The structural and mechanical properties of the fibers were characterized by DSC, X-ray, SEM, optical birefringence, and tensile testing. The results showed that the bath treatment increased considerably the fiber birefringence up to 0.066 by 66% and increased the crystallinity up to 47.94% by 100% compared to the control (no HIB) fibers. Drawing the HIB fibers with a low draw ratio (DR) of 1.11 increased the tensile strength up to 4.76 g/d and reduced the tensile strain down to 51.76%. Such strength is greater than the maximum value of 3.3 g/d reported before. The obtained results can widen application of PTT fibers in technical woven/nonwoven fiber products.}, number={10}, journal={SN APPLIED SCIENCES}, author={Najafi, Mesbah and Kotek, Richard}, year={2019}, month={Oct} }
 @article{yoon_avci_najafi_nasri_hudson_kotek_2017, title={Development of High-Tenacity, High-Modulus Poly(ethylene terephthalate) Filaments via a Next Generation Wet-Melt-Spinning Process}, volume={57}, ISSN={["1548-2634"]}, DOI={10.1002/pen.24406}, abstractNote={In this study, PET (intrinsic viscosity of 1.05 dl/g) was melt processed with a horizontal isothermal bath (HIB) treatment. Tensile properties of PET fiber samples were highly increased by using the HIB. The process-structure-property relationship of control (no HIB) and HIB fiber samples were characterized by tensile testing, differential scanning calorimetry, birefringence measurement, scanning electron microscopy and hot-air shrinkage measurements. It was found that HIB fiber samples, which had been subjected to post-drawing process, had a high degree of molecular chain orientation, that is, a high birefringence, high crystallinity and a fibrillar structure. The best tensile property acquired from a HIB-drawn PET fiber sample was 10.24 g/d in tenacity, 114.17 g/d in modulus, and 13.49% in elongation at break. Applying the HIB in the melt spinning process was simple and required only small process space; hence, it is cost effective. In addition, acquiring HIB fiber samples was successful at a final take-up speed of 2,500 m/min. Hence, this HIB-assisted melt spinning technology has a high potential to be used in industries for technical textiles applications. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers}, number={2}, journal={POLYMER ENGINEERING AND SCIENCE}, author={Yoon, Joshua H. and Avci, Huseyin and Najafi, Mesbah and Nasri, Lassad and Hudson, Samuel M. and Kotek, Richard}, year={2017}, month={Feb}, pages={224–230} }
 @article{najafi_nasri_kotek_2017, title={High-performance nylon fibers}, volume={187}, ISBN={["978-0-08-100550-7"]}, ISSN={["2042-0803"]}, DOI={10.1016/b978-0-08-100550-7.00009-7}, abstractNote={Nylon is one of the most important polymers for production of high-performance fibers. High tenacity, high elasticity, good adhesion to rubber, and resistance to heat, abrasion, and chemicals make it possible for nylon filaments/yarns to be used widely in various technical products such as tire cords, industrial threads, climbing ropes, and fishing nets. This chapter first reviews the recent developments in spinning and treatment methods of high-performance nylon fibers. These techniques affect different elements inside the fiber structure, improving the tensile, thermal, and chemical properties. To understand such effects the morphology and the physical and chemical characteristics of the filaments are explained in detail. Finally, this chapter provides some suggestions for future production of technical nylon fibers.}, journal={STRUCTURE AND PROPERTIES OF HIGH-PERFORMANCE FIBERS}, author={Najafi, M. and Nasri, L. and Kotek, R.}, year={2017}, pages={199–244} }
 @article{najafi_avci_kotek_2015, title={High-performance filaments by melt spinning low viscosity nylon 6 using horizontal isothermal bath process}, volume={55}, ISSN={["1548-2634"]}, DOI={10.1002/pen.24135}, abstractNote={Several techniques and treatments have been developed for the production of high-performance nylon-6 fibers. The inherent problems of low productivity, high production cost, and high energy consumption, complexity of chemical reaction, mass transfer, and waste recovery systems make most of them inappropriate for industrial application. Horizontal isothermal bath (hIB) is an alternative ecofriendly simple treatment that can be used during melt spinning process for production of technical textile fibers. The efficacy of hIB in improving the mechanical properties of multifilament nylon-6 yarn is studied in this research. The results showed that such treatment can increase the molecular orientation of the amorphous and crystalline functions up to 0.54 and 0.983, respectively, and raised both the amorphous isotropy and fiber birefringence by 67 and 45%, respectively. Hot drawing of the yarn at a very low draw ratio of 1.38, increased the tenacity and modulus up to 10 and 43.9 g/den, respectively, and decreased the elongation to 27%. POLYM. ENG. SCI., 55:2457–2464, 2015. © 2015 Society of Plastics Engineers}, number={11}, journal={POLYMER ENGINEERING AND SCIENCE}, author={Najafi, Mesbah and Avci, Huseyin and Kotek, Richard}, year={2015}, month={Nov}, pages={2457–2464} }
 @article{avci_najafi_kilic_kotek_2015, title={Highly crystalline and oriented high-strength poly(ethylene terephthalate) fibers by using low molecular weight polymer}, volume={132}, ISSN={["1097-4628"]}, DOI={10.1002/app.42747}, abstractNote={High-strength poly(ethylene terephthalate) (PET) fibers were obtained using low molecular weight (LMW) polymervia horizontal isothermal bath (hIB), followed by postdrawing process. We investigated the unique formations of different precursors, which differentiated in its molecular orientation and crystalline structures from traditional high-speed spinning PET fibers. Sharp increase in crystallinity was observed after drawing process even though the fibers showed almost no any crystallinity before the drawing. Properties of as-spun and drawn hIB and control filaments at different process conditions were compared. As would be expected, performances of resulted treated undrawn and drawn fibers have dramatically improved with developing unique morphologies. Tenacities more than 8 g/d for as-spun and 10 g/d for drawn treated fibers after just drawn at 1.279 draw ratio were observed. These performances are considerably higher than that of control fibers. An explanation of structural development of high-strength fibers using LMW polymer spun with hIB is proposed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42747.}, number={45}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Avci, Huseyin and Najafi, Mesbah and Kilic, Ali and Kotek, Richard}, year={2015}, month={Dec} }