Preparation and properties of polyphenylene‐1,3,4‐oxadiazole fibres

Copolymers of terephthalic and isophthalic acid (CPODZ) in 1:1 and 3:1 molar ratios with hydrazine sulphate and concentrated sulphuric acid were wet spun using water and H2SO4 coagulation baths. The filaments spun into water bath have inferior mechanical properties than those spun in H2SO4 bath. Physical properties, namely tenacity, elongation, modulus, resilience, elastic recovery, and dynamic mechanical properties were investigated. 1:1 CPODZ filaments showed higher strength, modulus and elasticity than 1:3 CPODZ filaments. These CPODZ fibres had a higher dynaic modulus and low loss tangent. The density and moisture regain of CPODZ filaments were also determined. The density of 1:1 CPODZ filaments was higher. The filaments spun in water bath had higher moisture regain. 1:1 CPODZ filaments had less regain compared to 1:3 CPODZ filaments.