共聚酯的合成与性能表征

以对苯二甲酸、乙二醇为主要原料,添加共聚单体新戊二醇(NPG)、5-叔丁基间苯二甲酸(tBI),通过熔融缩聚合成了一系列不同组成比例的共聚酯,分析了共聚酯的化学结构与组成、特性黏度、热性能、结晶性能和动态热力学性能。结果表明:随着tBI和NPG含量的增加,共聚酯的熔点降低,结晶能力逐渐减弱;当tBI和NPG物质的量分数总和达到13%及以上时,共聚酯为完全无定形态;tBI单元的加入使共聚酯的玻璃化转变温度升高,弥补了PENT共聚酯玻璃化转变温度低于PET的缺点;共聚酯的初始分解温度高于PET,初始储能模量大于PET,而随着测试温度的升高,共聚酯的柔韧性大于PET材料。

Synthesis and Characterization of Copolyester

A series of copolyester were synthesized through two-stage melt polycondensation reaction using pure terephthalic acid and ethylene glycol as main monomer, as well as by adding different amounts of the comonomers 5-tert-butylisophthalic acid(tBI) and neopentyl glycol(NPG). The chemical structure and compositions, intrinsic viscosities, thermal properties, crystallization properties and dynamic thermomechanical properties of copolyesters were investigated. The results exhibite that the melting point and crystallization properties gradually decrease as the increase of the contents of tBI and NPG units. When the molar fraction of tBI and NPG is 13% or more, the copolyesters are amorphous. The addition of the tBI unit increases the glass transition temperature(Tg) of the copolyesters, whicn makes up for the shortcomings of the glass transtition temperature of PENT copolyester lower than that of PET. The initial degradation temperature of the copolyesters are higher than that of the PET. The initial storage modulus of the copolyesters are stronger than that of the PET, but the flexibility of copolyesters are greater than that of the PET as the test temperature increases.