Synthesis of Semi-Aromatic Copolyester with High Molecular Weight

Abstract

The polymerization of para-acetoxybenzoic acid (PABA) and poly (ethylene terephthalate) to generate high molecular weight semi-aromatic copolyester was conducted successfully in the presence of acetic anhydride. The influence of acetic anhydride on the copolymerization was studied. The addition of acetic anhydride (2:1 mol AC2O /PET) in the polymerization system afforded the polymerized copolyester with an increased intrinsic viscosities (by 112.5%) and a decreased amount of insoluble fraction (by 80%). 1H-NMR analysis indicated that mole ratio of PET repeat unit and PHB was 42:58 with the addition of acetic anhydride, which was quite similar to the theoretical ratio and higher than traditional synthesized PET/PHB. The results show that the addition of acetic anhydride is effective not only in increasing the molecular weight but also in increasing benzene ring content in the copolyester.