초록
The effect of several kinds of terephthalic acid esters (di-o-chlorophenyl terephthalate, di-m-chlorophenyl terephthalate, diphenylethyl terephthalate, dimethyl terephthalate, bis (2-hy-droxyethyl) terephthalate (BHET), and diphenyl terephthalate (DPI)) on the polycondensation reaction of BHET was investigated. Terephthalic acid esters were added at the moment when thermal degradation started. The highest increase of molecular weight was observed when DPT was used. With other terephthalic acid esters the molecular weights were rather decreased or were similar to that of PET polycondensated without any added terephthalic acid esters. It was identified that the rate constants of ester interchange reactions of terephthalic acid esters and the reactivates of byproducts during polycondensation had a marked influence on the polycondensstion reaction of BHET. The results of GPC analysis suggested that the molecular weight distributions of PET samples should be affected by the addition of terephthalic acid esters.