连续原位聚合黑色PET的结晶行为研究

Crystallization behavior of black PET prepared by continuous in-situ polymerization

采用差示扫描量热法研究了连续聚合装置生产的原位聚合黑色聚对苯二甲酸乙二醇酯(PET)的等温结晶与非等温结晶行为。结果表明:在结晶过程中,原位聚合黑色PET中着色剂炭黑起到异相成核剂作用,使其结晶成核速率较PET提高,同时炭黑与PET分子链间的强相互作用会束缚PET分子链段的运动,导致原位聚合黑色PET结晶晶体生长受限;在等温结晶温度小于等于220℃的条件下,原位聚合黑色PET的结晶速率高于PET,但当等温结晶温度升高至224℃时,炭黑质量分数为3%的原位聚合黑色PET的结晶速率低于PET,与炭黑质量分数为2%的原位聚合黑色PET相比,炭黑质量分数为3%的原位聚合黑色PET结晶速率减小、晶体生长维数增大;在非等温结晶过程中,随着炭黑含量的增加,原位聚合黑色PET的结晶速率和结晶活化能绝对值均逐渐增大。

The isothermal and non-isothermal crystallization behaviors of in-situ polymerized black polyethylene terephthalate(PET)produced by continuous polymerization were studied by differential scanning calorimetry.The results show that the colorant carbon black in the in-situ polymerized black PET acts as a heterogeneous nucleator during the crystallization process,which makes its crystallization nucleation rate higher than that of PET,meanwhile,the strong interaction between carbon black and PET molecular chains will restrict the movement of PET molecular segments,resulting in the crystal growth restriction of in-situ polymerized black PET;the crystallization rate of in-situ polymerized black PET is higher than that of PET when the isothermal crystallization temperature is less than or equal to 220℃,however,the crystallization rate of in-situ polymerized black PET with 3%carbon black by mass fraction is lower than that of PET when the isothermal crystallization temperature is increased to 224℃;compared with in-situ polymerized black PET with 2%carbon black by mass fraction,the in-situ polymerized black PET with 3%carbon black by mass fraction has lower crystallization rate and higher crystal growth dimension;and the crystallization rate and the absolute value of crystallization activation energy of in-situ polymerized black polyester increase gradually with the increase of carbon black content during in the non-isothermal crystallization process.