SYNTHESIS OF COPOLY(ETHYLENE TEREPHTHALATE/IMIDE)S AND CRYSTALLIZATION KINETICS

Copoly(ethylene terephthalate/imide)s (PETI) were prepared by melt polycondensation of bis(2-hydroxyethyl)terephthalate (BHET) and imide containing comonomer, 4,4'-bis[(4-carbo-2-hydroxyethoxy)phthalimido]diphenylmethane (BHEI) with Sb2O3 as catalyst at 280 degrees C under vacuum (-1 mm Hg). The change of T-m with an increase of the BHEI repeat unit in the PETI copolymer was analyzed by the Flory equation. On isothermal crystallization, a longer induction time and a lower activation energy than for the PET homopolymer were observed with an increasing amount of the BHEI repeat unit. The Avrami exponent, n, increased from 1.5 to 2.3 as the content of BHEI or crystallization temperature was increased. The Avrami rate constant K decreased with the increase of the BHEI unit. On nonisothermal crystallization, the Ozawa equation and Lawton plot were used to investigate the effect of BHEI units on the crystallization kinetics of PETI copolymers. From the change of the cooling crystallization function and the result of the Lawton plot, it was found that the BHEI unit effectively decreases the rate of crystallizationclose8