The crystallization behaviors of poly(butylene terephthalate) blended withco[poly(butylene terephthalate-p-oxybenzoate)] copolyesters

Poly(butylene terephthalate) (PBT) was blended with three different kinds o f co[poly(butylene terephthalate-p-oxybenzoate)] copolyesters, designated B 28, B46, and B64, with the copolyester level varying from 2 to 15 wt.%. All samples were prepared by solution blending in a 60/40 by weight phenol/tet rachloroethane solvent at 50 degreesC. The crystallization behavior of samp les was then studied by DSC. The results indicate that these three copolyes ters accelerate the crystallization rate of PET in a manner similar to that of a nucleating agent. The acceleration of PET crystallization rate was mo st pronounced in the PBT/B28 blends with a maximum level at 10 wt.% of B28. The melting endotherm onset temperatures and the melting peak widths for t he blends are comparable with those of pure PET. These results imply that t he stability of PET crystallites in the blends is not significantly influen ced by blending. The observed changes in crystallization behavior are expla ined by the effect of the composition and the amount of copolyester in the blends. (C) 2000 Elsevier Science Ltd. All rights reserved.