熔融纺丝成形条件对PET初生丝超分子结构及其力学性能的影响——第2报 单丝线密度、喷丝头拉伸比及侧吹风速对PET初生丝结晶作用及力学强度的影响

本文考察了单丝线密度、侧吹风速度以及喷丝头拉伸比对PET初生丝结晶作用及力学强度的影响。表明PET初生丝的结晶作用对单丝线密度的变化极为敏感。当单丝纤度减少时,初生丝的结晶度、侧向晶粒尺寸均大幅度增加,且最大结晶度出现的位置移向低纺速区。增大喷丝头拉伸比的作用有点类似于减少单丝线密度。但当喷丝头拉伸比超过一定值之后,结晶度虽仍在增加,而侧向晶粒尺寸却似乎已达饱和值。强化冷却条件,即加大侧吹风速,虽然也能使PET初生丝的结晶度和侧向晶粒尺寸增加,但其作用却并不象我们所预期的那么大。此外,实验还表明,除单丝线密度变化时,PET初生丝的断裂强度出现反常现象外,一般说来断裂强度总是随取向度和结晶度的增加而增大,延伸度则相应减小。

EFFECT OF FORMATION CONDITION IN MELT SPINNING ON THE SUPERMOLECULAR STRUCTURE AND THE MECHANICAL PROPERTY OF PET SPUN FILAMENT PT. Ⅱ EFFECT OF SINGLE FILAMENT LINEAR DENSITY,SPIN-DRAW RATIO AND LATERAL BLOW SPEED ON THE CRYSTALLIZATION AND THE M

In this paper, the effects of single filament linear density ,spin-draw ratio and lateral blow speed on the crystallization and mechanical property of PET spun filament are investigated. By decreasing the single filament linear density both the crystallity and lateral crystal size will increase greatly and the largest crystallini-ty appears with lower spinning speed. Similar effet is obtained by increasing the spin-draw ratio but when it exceeds a certain value although the crystallinity is still increasing the lateral crystal size seems reach its maxmium. It can also be done with increasing lateral blow speed but is not so effective as expected,in general, increasing the degree of orientation and cry stallization of PET spun filament will result in the improvement of breaking strength and decrease of breaking elongation but there is the exception when single filament linear density is changed.