POLYMER BLENDS OF POLY(P-PHENYLENE 1,3,4-OXADIAZOLE) AND POLY(P-PHENYLENE TEREPHTHALAMIDE) - MORPHOLOGY AND MECHANICAL-BEHAVIOR

Film specimens and blend fibres of poly(p-phenylene 1,3,4-oxadiazole) (p-PODZ) and poly(p-phenylene terephthalamide) (PPTA) have been prepared. Morphologies were studied by optical and electron microscopy. Transparent films could be coagulated from ternary solutions under conditions that prevent large-scale phase separation while morphologies change in blend fibres with composition. A fibril matrix morphology is formed at low PPTA contents. Co-continuous morphologies result when the PPTA fraction increases and, finally, p-PODZ is spherically dispersed in PPTA. The mechanical behaviour has been examined using stress-strain and drawing experiments. The modulus of elasticity increases strongly when small amounts of PPTA are added to p-PODZ. The results are discussed in terms of the Halpin-Tsai model.