通过聚对苯二甲酸丙二酯(PTT)与三氟乙酸(TFA)发生封端反应,制得末端修饰后的PTT(PTT-TFA),并用差示扫描量热仪(DSC)系统地研究了它的热性能.结果表明,PTT-TFA的熔点为227.3 ℃,与纯PTT相同,但PTT-TFA熔体的起始结晶温度略向低温方向移动,且结晶速率比纯PTT的低.用Friedman法测定的体系的结晶活化能结果表明,PTT-TFA的结晶能力下降.由于末端修饰的分子链末端基的体积增大,所以分子链的运动能力降低,因而造成熔体结晶速率降低.
End-group modified poly(trimethylene terephthalate) polyester (PTT-TFA) was prepared by the esterification reaction between the hydroxyl end-groups of PTT and trifluoroacetic acid at room temperature, and its thermal properties were investigated by using the differential scanning calorimetry (DSC). The results show that the melting point of PTT-TFA was 227.3 ℃, which is equal to pure PTT, but the crystallization temperature is lower than that of pure PTT. Furthermore, the crystallization rate of PTT-TFA is also lower than that of pure PTT. The effective activation energy of crystallization calculated by Friedman method also concludes that the PTT-TFA has lower crystallization ability than pure PTT. Since the end-groups of the modified polymer were larger than that of the pure PTT, the mobility of the molecular chain was decreased; this lowered the rate of melt-crystallization.
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