聚对苯二甲酸-联苯二甲酸-乙二酯的分子序列结构与结晶性能

Molecular Sequence Structure and Crystallization Behavior of Poly(ethylene terephthalate-co-4,4'-bibenzoate)

以对苯二甲酸、联苯二甲酸(BBA)和乙二醇为原料,采用直接酯化技术制备了聚对苯二甲酸-联苯二甲酸-乙二酯(PETBB).特性黏度和凝胶渗透色谱(GPC)测试表明得到了高相对分子质量的共聚物.13C-NMR证实PETBB大分子链上所含的BBA与投料比一致;随着BBA摩尔分数的增加,共聚酯中聚对苯二甲酸乙二酯(PET)平均序列长度减小而聚联苯二甲酸乙二酯(PEBB)平均序列长度增大.差示扫描量热(DSC)分析证明PETBB共聚酯自熔体冷却的结晶温度变低,较高BBA摩尔分数的PETBB甚至不能在熔体冷却过程中结晶,表明共聚酯结晶变得困难,但经充分热定型仍能形成晶体;而其熔融温度随BBA摩尔分数的增加而明显下降;玻璃化转变温度则随BBA摩尔分数的增加而升高.

4,4＇-bibenzoic acid （BBA） was used to replace certain amount of terephthalate acid together with ethylene glycol to produce poly（ethylene terephthalate-co-4,4＇-bibenzoate） （PETBB） via the conventional direct esterification technique.The results of intrinsic viscosity and gel permeation chromatography （GPC） measurements indicated that the molecular weights of PETBB were fit for practical use.It was also proved from the analysis of 13C-NMR that the chemical composition of BBA in PETBB was identical with the feed ratio,and the number-average sequence length of polyethylene terephthalate （PET） segment reduced while the number-average sequence length of polyethylene bibenzoate （PEBB） segment increased a little with the increasing of mole fraction of BBA.Moreover,the results of differential scanning calorimeter （DSC） showed that the incorporation of BBA would reduce the crystallization temperature of PETBB from the melting state,and the crystallization could hardly carry out if the mole fraction of BBA was high enough.Even though the crystallites could be obtained through the fully annealing,but they would be melted under the lower temperature when more BBA were used.Furthermore,the glass transition temperature of PETBB increased almost linearly with the increasing of mole fraction of BBA.