CHDM改性PTT共聚酯非等温结晶动力学研究

Non-isothermal crystallization kinetics of PTT copolyesters modified with CHDM

以对苯二甲酸(PTA)、1,3-丙二醇(1,3-PDO)和1,4-环己烷二甲醇(CHDM)为原料,通过酯化缩聚工艺路线制备了CHDM改性聚对苯二甲酸1,3-丙二醇酯(PTT)共聚酯——聚对苯二甲酸1,3-丙二酯-1,4-环己烷二甲酯共聚酯(PTTG)。借助乌氏黏度计和差示扫描量热(DSC)仪测试了PTT和PTTG的特性黏数、黏均相对分子质量和非等温结晶性能,并采用Jeziorny法研究了PTT和PTTG的非等温结晶动力学。结果表明:PTT和PTTG的特性黏数均大于0.7 dL/g,黏均相对分子质量均大于20000;随着CHDM用量的增加,PTTG的结晶温度和结晶能力下降;PTTG的成核结晶方式复杂,PTT与PTTG的Avrami指数无较大变化,CHDM对PTT的晶体成核影响较小;随着CHDM的加入,PTTG的非等温结晶速率常数升高,结晶速率加快,导致PTTG结晶不完全,结晶能力下降。

Polytrimethylene terephthalate(PTT)copolyesters modified with 1,4-cyclohexanedimethanol(CHDM),namely poly(1,3-propanediester-1,4-cyclohexanedimethyl terephthalate)copolyester(PTTG),was prepared by esterification polycondensation process using terephthalic acid(PTA),1,3-propanediol(1,3-PDO)and 1,4-cyclohexane dimethanol(CHDM)as raw materials.The intrinsic viscosity,viscosity average relative molecular mass and non-isothermal crystallization properties of PTT and PTTG were measured with an Ubbelohde viscometer and differential scanning calorimeter(DSC).And the non-isothermal crystallization kinetics of PTT and PTTG were studied by Jeziorny method.The results showed that the intrinsic viscosities and viscosity average relative molecular mass of PTT and PTTG were both higher than 0.7 dL/g and 20000,respectively;the crystallization temperature and crystallization behavior of PTTG decreased with the increase of CHDM content;the nucleation and crystallization of PTTG was complex and the Avrami index of PTT and PTTG had no significant change,which indicated that CHDM had little effect on the nucleation of PTT;and the non-isothermal crystallization rate constant of PTTG increased and the crystallization accelerated with the addition of CHDM,resulting in the incomplete crystallization and crystallization ability descent of PTTG.