单向和双向拉伸聚乙烯薄膜的晶体取向表征

Characterization on the crystalline orientations of uniaxially and biaxially oriented polyethylene films

对聚乙烯流延片分别进行单向拉伸和双向拉伸,利用WAXD和SAXS方法对拉伸薄膜进行了表征。采用X射线衍射反射极图分析了单向和双向拉伸聚乙烯薄膜的晶体取向,计算了聚乙烯薄膜不同晶面的Hermans取向因子。同时用透射方法得到了聚乙烯薄膜的晶体和片晶的取向因子。表征结果显示,单向拉伸聚乙烯薄膜晶体的c轴沿着纵向方向择优取向,双向拉伸聚乙烯薄膜晶体的c轴则沿着横向方向弱取向。这两种拉伸后的聚乙烯薄膜的结晶形态均为Keller/MachinⅡ型,片晶没有发生扭转。

Polyethylene（PE） base sheets were uniaxially and biaxially stretched into films,respectively.The WAXD and SAXS techniques were used to characterize these films.WAXD pole figures obtained by the reflection mode were used to analyze the crystalline orientations of uniaxially and biaxially oriented PE films.The Hermans orientation factors of different lattice planes were calculated.The orientations of crystallites and lamella were also analyzed by using WAXD and SAXS in transmission mode,respectively.The results showed that the caxis of the PE crystal was oriented along the machine direction（MD） for the uniaxially oriented PE film,while the caxis of the PE crystal was oriented along the transverse direction（TD） slightly for the biaxially oriented PE film.The crystalline morphologies of these films showed the Keller/Machin Ⅱ type with no twisting of the lamella.