Synthesis and characterization of PET block copolymers containing long aromatic segments

In this paper, the reaction of dimethyl terephthalate (DMT) and p-hydroxybenzoic acid (PHB) was carried out to synthesize rigid molecule, which was used as the third monomer in the melt polycondensation with terephthalic acid (PTA) and ethylene glycol (EG) to prepare PET block copolymer containing rigid aromatic segments. From FTIR it is conformed that the third monomer was mainly a series of low molecular weight products by transesterification and esterification. Poly(ethylene terephthalate) (PET) and it's block copolymer with different contents of the third monomer (0.5%, 2%, 4%, mol ratio relative to PET) were prepared. The structure and properties of PET copolyesters were studied and compared with pure PET by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and polarized optical microscopy (POM), etc. The copolymers exhibited significant different properties compared with pure PET.