PP/PET原位成纤复合材料的增强效应

用挤出-拉伸-注塑法制得了PP/PET原位成纤增强复合材料,以不拉伸的普通共混材料作对照,研究了PET质量含量(C_m)对PET成纤性和材料拉伸强度(σ_t)及模量(E)的影响及其作用机制。结果表明,C_m由0增至20%时,PET纤维数量增多,纤维直径及其分散性以C_m=15%为界先减少后增大;材料的σ_t、E在C_m=15%时有最大值,分别比纯PP提高约20%和70%。熔体拉伸时分散相液滴的聚结-形变成纤对PET相形态随C_m的变化起关键作用,分散相对基体增强效应与两相界面缺陷效应的相互竞争,纤维对基体增刚作用受纤维数量和细度的双重控制,分别是决定材料σ_t~C_m、E~C_m关系的支配因素。

REINFORCING EFFECT OF PP/PET IN-SITU FIBERIZED COMPOSITES

The PP/PET in-situ fiberized composites with reinforcing effect were prepared by extrusion-drawing-injection molding. The influences of PET mass content (Cm) on the PET fiberization, tensile strength (σt) and Young's modulus (E) of the composites, together with their functional mechanisms were studied in contrast to the normally blended materials without drawing. The results show that as Cm rises from 0 to 20%, the number of PET fibers in-situ formed increases whereas their diameter and dispersity decrease till Cm=15% and then increase.Correspondingly, the σt and E of the composites increase till Cm=15% and then decrease, with maximum gains of σt and E of about 20% and 70% relative to neat PP,respectively. The fiberization of PET droplets through coalescence-deformation during melt-drawing plays a key role in the above variation of PET phase morphology with Cm. The competition between the reinforcing effect of dispersed phase on matrix and the interfacial flaw effect of the two phases, and the rigidizing effect of fiber on matrix controlled by both fiber number and fiber fineness, are dominant factors of deciding the above σt~Cm and E~Cm relations, respectively.