Studies On Fiber Formation Mechanism In Melt-spinning Process And Development Of HMLS Polyester Fibers

Melt-spinning is one of the most important process of fiber formation and the mechanism of fiber formation is still a hot spot that scientist and engineer are interested in today. In this paper, we have systemically investigated the formation of melt-spinning process, developing of the continuity, momentum balance, energy balance, constitutive, orientation and crystallization equations and some special parameter expression. Using the counter-simulation methods, we also have modified and optimized some equations and expressions, like constitutive equation, elongation viscosity expression etc.. Based on these research work, we have developed mathematic models and a simulation system for various melt-spinning processes by MATLAB, such as High-speed and low-speed spinning, TCS, hollow, heteromorphism, and composite melt-spinning etc.. Combined with the new process and new products, we have developed their characteristic equations and models, especially for hollow, heteromorphism and composite fibers. Based on the results of simulation and applying highspeed spinning and high-temperature high-tensile process, we have prepared the low and high viscosity HMLS polyester fibers, and studied the relationships among the process, structure and properties by various testing methods, like WAXS, SAXS, DDV, DSC, S-S etc..The simulation results of high-speed spinning show: stress-induced orientation and orientation-induced crystallization exist obviously during this process, and the results of simulation approximately match with the experiment data, which testifies that the model and parameter expression are reasonable. The simulation results of asymmetry cooling process in high-speed spinning also show: there is obvious structure asymmetry affected by the imbalance of temperature on the section of spun. The area of highest temperature tends to be the side against the cooling wind. And mass throughput is one of the most important factors affecting the asymmetry structure.With the basis of the theory on simulation of thermal channels, we have developed a model of fancy spinning process. During spinning,because of the different temperature between the thermal and cool channels and the special shrinking, great difference in formation process happened. Adjustment of the position and diameter of cool channel has little influence to fiber formation, while the adjustment of the position and diameter of thermal channel can reduce the difference of stress.The simulation results of hollow fiber formation process show: the changes of hollow form happened in the melted area, and the skin-core structure is formed mainly in cooling area. The temperature difference between skin and core decreases with the increase of mass throughput, while take-up speed has little effect on it. Throughput is also the mam factor of affecting the hollow fiber formation. Heated roller spinning process and H4S mathematics models have been developed. Skin-core composite spinning process model has also been developed by using asymmetrical cooling mechanism and viscoelastic constitutive equations. And the model of triangle heteromorphism fibers has established by using three-dimensional axis.Comparing with the industrial fiber LS and HM, HMLS fibers prepared by high-speed spinning under high- temperature with high-tensile conditions require higher spinning speed to obtain higher pre-orientation (birefringence 0.25-0.35). The dimensional stability of fiber remarkably increases with the increase of spinning speed. We have investigated the super molecular structure of HMLS fiber by WAXS, SAXS, DSC. The results show that HMLS fibers have higher degree of crystallinity and orientation, lower crystal size, and higher structure regularity. For mechanical properties, HMLS fibers have higher modulus and tenacity, lower strain and shrinkage, higher medial- modulus and magnifying ratio of stress. In addition, Applying rubber-elastic theory, we have investigated the shrinking process of HMLS fibers. The results show that the degree of cross-linking is much higher...