Structure development in melt spinning filaments from polybutylene terephthalate based thermoplastic elastomers

Structure development in polybutylene terephthalate (PBT) and thermoplastic elastomers (TPEs) based on PBT during the melt spinning process was investigated. Melt spun filaments were examined using wide angle X‐ray diffraction and birefringence. Crystalline orientation was characterized in terms of Hermans‐Stein orientation factors. Crystalline orientation and birefringence were found to correlated with spinline stress better than drawdown ratio. Crystalline orientation development was strongly dependent on spinline stress. The TPEs with low PBT content had low birefringence although the crystalline orientation was often high.