Study on crystallization performance of polyethylene terephthalate/polybutylene terephthalate alloys

Polyethylene terephthalate (PET) is a kind of high performance engineering plastic. However, the application of pure PET is subject to limitation because of its slow crystallization rate. In order to overcome this difficulty, thermoplastic resins are often added into PET matrix by a compounding technique. Polybutylene terephthalate (PBT) possesses many advantages such as a high degree of crystallinity and rapid molding, thus, is very suitable to adjust the crystallization behaviors of PET. In this work, the crystallization behaviors of PET/PBT alloys were studied by a differential scanning calorimeter (DSC) and thermal platform polarizing microscope. The obtained results indicate that the content of PBT could tune the melting and crystallization behaviors of the alloy. The parameters of non-isothermal crystallization of the alloys for blends were analyzed by the Jeziorny and Kissinger methods. The non-isothermal crystallization process for PET, PBT and PET/PBT alloys fit the Jeziorny model well at the early stage, but there is a certain small deviation at the later stage, indicating that the nucleation mechanism of PET/PBT alloy is complicated. In addition, the crystallization rate accelerates with an increase in cooling rate. The alloys show the best crystallization performance when the content of PBT is 10 wt%, and their crystallization activation energy reaches up to -201.78 kJ/mol.