Modification of Poly(ethylene terephthalate) Fibre by Polymer Blending with Poly(butylene terephthalate) Fibre: Part III-Simultaneous Melt-blending and Spinning

The blend fibres prepared from poly(ethylene terephthalate) and 0-10% poly(butylene terephthalate) by sequential melt-blending and spinning show a single glass transition temperature, less than that of 100% PET. The melting point of the blend fibres is lower than that of 100% PET owing to decrease in crystalline order and partial transesterification. The thermal stability of the blend fibre decreases on addition of more than 3% PBT. Addition of 3% poly(butylene terephthalate) to poly(ethylene terephthalate) increases birefringence, initial modulus, sonic modulus and tenacity, which may be associated with higher inter-crystalline links.