有序定构聚集态β-iPP薄膜的重结晶行为研究

The Crystallization Behavior of β- iPP Film with Different Ordered Melt Structures

采用熔体挤出-拉伸法制备了稀土类β成核剂改性等规聚丙烯(iPP)薄膜.然后将上述薄膜加热到不同熔融温度,通过差示扫描量热法(DSC)和偏光显微镜(POM)实验分别考察了有序熔体结构对β-iPP薄膜非等温和等温结晶行为的影响.结果表明:在非等温结晶过程中,随着设定温度(T_m)的降低,部分熔融的β-iPP能够诱导形成更多成核位点,使其在较高温度下发生结晶;同时,试样中诱导形成密集的柱晶结构.在等温结晶过程中,当165℃<T_m<169℃时,在试样内部会发生β晶向α晶转变;然而当169℃<T_m<172℃时,在试样内部的α晶逐渐向β晶转变.

The rare earthβ-nucleating agent modified isotactic polypropylene(iPP)films were prepared by melt extrusion-stretching method.Subsequently,the films were heated to different melting temperatures.The influence of ordered melt structures on non-isothermal and isothermal crystallization behavior ofβ-iPP films were investigated by DSC and POM experiments.The results indicated that,during the non-isothermal crystallization process,the partially meltedβ-iPP could induce the formation of more nucleation sites with decreasing crystallization temperature;and then inducing the crystallization at higher temperature.Meanwhile,the dense cylindrite was formed in samples.During the isothermal crystallization process,when the 165℃≤Tm<169℃,theβcrystal was transformed intoαcrystal in the sample;however,when the 169℃≤T m≤172℃,theαcrystal in the sample gradually changed into theβcrystal.