热处理过程中聚酯长丝的形态变化

在自制的红外三因素处理机上~1],用红外加热在定张力下对聚对苯二甲酸乙二酯(PET)成品长丝进行热处理(二次定型)。用X-光衍射(WAXS)、X-光小角散射(DAXS)、红外光谱(IR)和双折射方法,测定样品的热收缩、结晶度、晶粒尺寸和取向、非晶取向、长周期和链折叠带强度。所得形态参数的变化表明,处理温度在200℃以上时,张力不再阻碍链折叠。不同定张力样品的形态研究表明,存在阻碍链折叠的某个张力转折值。本文条件下,这个张力值为f_(critical)=0.066g/dtex 。张力大于此值,链折叠过程受阻。

MORPHOLOGICAL CHANGES OF POLY (ETHYLENE TEREPHTHALATE) FILAMENTS ON HEAT TREATMENT

Drawn commercial yarns of poly ethylene terephthalate (PET) multifilament were heat treated (secondary setting) by infra red heat source on a three-factor heat-treat equipment made by our laboratory. By means of wide-angle X-ray Diffraction (WAXS), Small-Angle X-ray Scattering (SAXS) and IB Specfcroscopy, heat shrinkage, crystallinity, crystallite orientation and size, non-crystalline orientation, long period and regular folded conformation band intensity of the treated yarns were measured. The change of these structural parameters showed that the tension was not able to prevent molecular chain refolding above 200℃. Under constant tension treatment a critical value of tension fcritical = 0.066 g/dtex was found, above which the tension will prevent chain refolding.