聚乙烯流延膜雾度研究

摘要

对2个雾度不同的聚乙烯流延膜试样,采用雾度仪通过表面涂覆石蜡的方法区分表面雾度和内部雾度.利用白光干涉三维轮廓仪、偏光显微镜和激光光散射研究了试样表面和内部的微观结构.通过高温凝胶渗透色谱、高温核磁共振碳谱、升温淋洗分级等手段表征了试样的分子结构,并采用差示扫描量热仪分析了试样的结晶行为.结果表明:2个试样的相对分子质量及其分布差异小,流延过程中分子流动性接近,导致薄膜的表面粗糙程度基本相同,表面雾度基本相同;2个试样的共聚单体含量不同,导致分子链结晶性能不同,共聚单体含量低,结晶性能好,球晶尺寸大,内部雾度大.%The surface and inner haze of two cast polyethylene(CPE)films in different haze values were identified via paraffin coating with haze instrument. The surface and inner microstructures of the CPE films were investigated by white light interferometer(WLI),polarized light microscope(PLM),laser scattering (LS). The molecular structure of the samples were characterized by gel permeation chromatograph(GPC), 13C-nuclear magnetic resonance(13C-NMR)spectrometer,temperature rising elution fractionation (TREF). The crystallization behaviors of samples were observed by differential scanning calorimeter(DSC). The results indicate that the similar molecular weight and molecular weight distribution of two samples as well as molecular flow behavior have resulted in the identical surface roughness and surface haze. However,the comonomer contents in samples are found quite different,which has led to various crystallization properties of molecular chains.The lower comonomer content brings about the better crystallization properties ,the larger pherulites formed and higher internal haze.