埃洛石对聚丙烯结晶行为的影响

Influence of Halloysite on Crystallization Behavior of Polypropylene

以埃洛石（HNT）掺杂的高效MgCl2/TiCl4催化剂催化丙烯聚合,制备了含HNT纳米管（w=（20 ～200） ×10^-6）的聚丙烯（PP）树脂（PP-HNT）,利用DSC方法研究了PP-HNT树脂的等温结晶动力学.由Avrami方程所得的结晶动力学参数表明,与纯PP相比,PP-HNT树脂的半结晶时间明显缩短,结晶速率常数增大.由Hoffman-Lauritzen方程研究球晶生长过程表明,与纯PP相比,PP-HNT树脂的链折叠自由能偏高,球晶生长速率降低.由于等温结晶速率由成核速率控制,故推测HNT使聚合物的成核速率加快,总的结晶速率加快.用偏光显微镜表征树脂的结晶形态显示,与纯PP相比,PP-HNT树脂的晶核密度增大,球晶尺寸减小.

Polypropylene（PP） resins containing halloysite （ HNT ） （ w = （ 20 - 200 ） × 10^ -6 ） nano- tubes（PP-HNT） were prepared with MgCl2/TiCl4 catalyst in situ doped with HNT. The isothermal crystallization kinetics of the neat PP and PP-HNT resins were investigated by means of DSC. The isothermal crystallization kinetic parameters were analyzed by Avrami equation and it was showed that the crystallization half-time was significantly decreased due to HNT filling and the crystallization rate constant increased. The spherulite growth was investigated by Hoffman-Lauritzen equation and it was revealed that the chain folding energy of the PP-HNT resins was higher than that of neat PP, which indicated that the spherulite growth rate decreased. It was concluded that HNT could accelerate the crys- tallization of PP due to its nucleating effect. Polarized light micrographs showed that, the PP-HNT res- ins had smaller crystallite size and higher nucleus density than neat PP.