Crystallization of poly(butylene terephthalate) blends containing liquid crystalline polymer component

Blends of poly(butylene terephthalate) (PBT) with thermotropic liquid cryst alline polymer (LCP) concentration down to 0.2 wt.% were prepared to invest igate the effects of LCP component on the crystallization behavior of PET. The crystal structure of PET in the blends was not deteriorated by the pres ence of LCP. The regularity of PET crystals in the blends with lower LCP co ntent appeared to be more perfect, compared with that of pure PET sample an d of blends with high LCP content. The experimental results revealed that t he LCP component may affect, to a great extent, the crystallization process of the blends due to the inhomogeneous nature of the LCP used. The crystal lization process of PET in the blends was very sensitive to the LCP content and its microstructures existing in the melt before the start of crystalli zation, with the nucleation effect of the LCP component in its crystalline state being more efficient than that in its nematic state. The favorable co ntent at which the LCP microdomains show "the most efficient nucleation" is more likely to occur at lower LCP content for these systems. Based on the fact that the addition of the LCP component leads to higher crystallization temperature, crystallinity and degree of perfection of the crystallites fo rmed, it is proposed that the effects of heterogeneous nucleation dominate in the crystallization process of the blends with lower LCP concentration. (C) 1999 Elsevier Science Ltd. All rights reserved.