Chaosheng Wang

Synthesis and Non-isothermal Crystallization Behavior of PET/Surface-treated TiO 2 Nanocomposites

Poly(ethylene terephthalate) (PET)/TiO 2 nanocomposites were prepared by melt-blending PET and surface-treated TiO 2 . The crystallization behavior and the non-isothermal crystallization kinetics of these composites were investigated by differential scanning calorimetry (DSC). Jeziorny and Mos methods were applied to describe the kinetics of the non-isothermal crystallization process. It was found that the PET matrix with incorporated surface-treated TiO 2 particles has lower crystallization temperature and melting point than that with incorporated pure nano-TiO 2 particles. Unlike plain TiO 2 , surface-treated TiO 2 particles showed less effect on the degree of crystallization of the PET matrix.

Crystallization behavior of rare-earth doped luminous pigment/polyamide 6 composites

The crystallization behavior of well‐dispersed rare‐earth doped luminous pigment/polyamide 6 (PA6) composites prepared through in situ polymerization was investigated by DSC. The rare‐earth doped luminous pigments could accelerate the forming of γ form crystals and also had a great effect on the crystallinity and crystallization rate of PA6 composites. The Ozawa, Jeziorny, and Mo methods were used to analyze the non‐isothermal crystallization kinetics. It was found that the Ozawa method was unsuitable for non‐isothermal crystallization of PA6 composites. The results of Jeziorny analysis showed that the crystallization rates of PA6 composites increased when the luminous pigment content was larger than 5 wt.%. Mos analysis also showed that the presence of the pigment shortened the crystallization time and accelerated the crystallization rate. Polarized optical microscopy showed that the spherulites became smaller with increasing of the luminous pigment amount due to the heterogeneous nucleation.

Multifilament Model of PET Melt Spinning and Prediction of As‐spun Fiber's Quality

Based on the multifilament model with cross air blowing proposed by Dutta (1987) and the assumption that the quench air temperature around the filament obeys an exponential distribution, a multifilament model suitable for the annular air blowing condition of PET staple fiber melt spinning is proposed. The quench air velocity, quench air temperature, filament velocity, filament temperature, etc. at different positions were predicted and the relation between birefringence and the important quality index of as‐spun fiber, Eys1.5 (elongation corresponding to 1.5 times the yielding stress in a stress‐strain curve) was obtained through experiment. The as‐spun fiber properties of PET staple and its variability were predicted and the effects of spinning conditions and spinneret design on as‐spun fiber properties were discussed and verified.

Dynamic modeling of dry-jet wet spinning of cellulose/[BMIM]Cl solution: complete deformation in the air-gap region

During the dry-jet wet spinning process of cellulose solutions with 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as solvent, the special viscoelastic characteristics of the solution lead to a large air-gap distance where the extruded flow can extend completely before entering the coagulation bath. Therefore, online measurement of diameter and temperature can be carried out and the velocity on the spinning line determined reasonably. Therefore, a model of dry-jet wet spinning is proposed to simulate the extrusion and extending dynamics of cellulose/[BMIM]Cl solutions in the air-gap region with complete deformation. Material parameters such as the density and heat capacity were determined by experiment, and the heat transfer coefficient along the spin-line was evaluated by an inversion procedure involving online experimental data for temperature and diameter. A two-dimensional (2-D) approach in POLYFLOW was adopted to compute the dynamic parameters along both the axial and radial directions of the spinning line. The numerical results were verified by comparison with experimental data including temperature and diameter. It was found that the contraction flow in the spinneret orifice could not be neglected and use of a nonisothermal viscoelastic model in the constitutive equation gave better agreement between simulation and experiment.

In situ polymerization and characterization of graphite nanoplatelet/poly(ethylene terephthalate) nanocomposites for construction of melt-spun fibers

A set of novel nanocomposites based on graphite nanoplatelets (GnP) and poly(ethylene terephthalate) (PET) were synthesized using an in situ polymerization approach that were subsequently being spun into fibers on a melt spinning apparatus. The GnP/PET nanocomposites with a filler weight fraction below 2% showed a homogenous fractured surface as a result of good dispersion of GnP in the PET matrix through preliminary dispersant treatment coupled with subsequent melt compounding during the polymerization. Compared to unmodified PET, the GnP/PET nanocomposites were confirmed to improve thermal stabilities and increase crystallization rates which were capable of facilitating the downstream procedure of melt spinning. At a low level of GnP loading, the PET matrix nanocomposite fibers were readily melt-spun without detecting fiber breakage or filament defect and exhibited mechanical properties similar to unmodified PET fiber as the compact interaction was formed between GnP and PET matrix. Particularly, the volume resistivity of the resultant nanocomposite fibers was found to be substantially reduced due to the intrinsic electrical conductivity that the GnP imparts as a filler. Taken together, our work introduces a simple and environmentally friendly method for melt spinning of GnP/PET nanocomposite fibers with great potential for applications in antistatic textile and military industries.