Study on Structure and Properties of Polypropylene/Polyamide 6 Blend Fiber. (Part V). The Changes of Structure and Tensile Strength and Elongation Characteristics for the Polypropylene/Polyamide 6 Blend Fibers upon Drawing.

Abstract

The changes of structure and tensile strength and elongation characteristics of polypropylene/polyamide 6 (hereafter “PP/PA6”) blend fibers upon drawing were investigated. Two melting peaks appeared, probably caused by the drawing of the PA6 component. The peak temperature of the PA6 component situated on the lower temperature side increased with increasing drawing ratio and with the PP content. Such melting behavior might be closely related to the crystal perfection and size developed in the PA6 component.In respect to the crystallinity of the blend fibers, the PA6 component was hardly affected by draw ratio and blend ratio. On the other hand, the PP component exhibited a higher crystallinity by draw. The X-ray diffraction patterns were examined. The undrawn blend fibers exhibited an orientation of PP crystals. However, the DebyeScherrer ring from PP crystals did not disappear even at draw ratio until 4.8. This indicates that the increment of PP crystalline orientation in the blend fibers with draw was smaller than that of the PP fibers.The tensile strength and elongation characteristics for the blend fibers depended largely on the blend ratios. At a given draw ratio, the strength increased with PA6 content. It was shown that the strength of the blend fibers was largely governed by the content of PA6 component rendering a high strength. The elongation decreased with increasing PA6 content.