典型工艺聚烯烃薄膜的雾度与其结构的关系

Relationship between haze-structure of polyolefin films by typical processes

测试了典型工艺得到的聚烯烃薄膜的雾度及透射率,利用WLI、LS、AFM和2D-WAXD等方法对薄膜的表面结构和内部结构进行了表征,并分析了结构与薄膜雾度的关系。表征结果显示,对于典型工艺的聚乙烯薄膜,吹膜的雾度大于流延膜的雾度;聚乙烯表面雾度与表面粗糙度具有线性相关性,内部雾度与球晶的尺寸有正相关关系;聚乙烯薄膜的表面和内部可以呈现不同的取向特征。市场上的聚丙烯薄膜大部分由流延法或双向拉伸法制得;双向拉伸薄膜内部通常没有完善的球晶结构,内部雾度非常低。对比聚乙烯薄膜和聚丙烯薄膜可知,表面雾度与表面粗糙度和表面结构特征有关。聚丙烯薄膜中大区域的表面起伏会明显增加表面粗糙度,但对表面雾度贡献很小。

Haze and transmittance of polyolefin films by typical processes are determined.The surface and internal structures of the films are characterized using WLI,LS,AFM and 2D-WAXD methods,and the relationships between haze and structure are analyzed.The results show that for polyolefin films by typical processes,the haze of blow films is usually larger than that of cast films.The surface haze of polyethylene has a linear correlation with surface roughness,and the internal haze presents a positive correlation with the size of the spherulite.The orientation feature of the surface layer and the internal layer of polyolefin films can be different.Most polypropylene films in the market now are cast films and bi-oriented films.There is usually no well-defined spherulite structure in the bi-oriented film,so the internal haze is usually very low.Comparing with polyethylene films and polypropylene films,the surface haze depends both on the surface roughness and the structure feature of the surface.Surface undulations in large areas of polypropylene film can significantly increase surface roughness,but contribute little on the surface haze.