LLDPE/IPP共混物高取向薄膜的附生结晶

本文用透射电子显微术、电子衍射等方法研究了线性低密度聚乙烯(LLDPE)和等规聚丙烯(IPP)共混物高取向薄膜的形态结构.在熔体拉伸薄膜中统组分的LLDPE与IPP均以高取向的片晶形式存在,片晶生长方向垂直手拉伸方向.当共混物中LLDPE含量较低(小于40％)时,作为分散相的LLDPE在IPP上附生结晶.两种片晶的c轴成45°交角,附生结晶的接触面为LLDPE的(100)和IPP的(010).而在LLDPE含量大于50％时,LLDPE形成独立的相区,则不存在附生结晶现象,结果两种片晶的生长方向均垂直于拉伸方向.在135℃热处理15min,然后自然冷却的LLDPE/IPP共混物薄膜中,当LLDPE含量≤50％时,LLDPE仍然在IPP上附生生长,二者的结构关系与热处理前的相同.

EPITAXIAL CRYSTALLIZATION IN HIGHLY ORIENTED LLDPE/IPP BLEND

Epitaxial crystallization of highly oriented films of LLDPE/IPP blends has been studied in this work by means of trsamission electron microscopy. The melt-drawn films of pure LLDPE or IPP consist of highly oriented lamellar structure. The growth direction of LLDPE and IPP lamellae is perpendicular to the drawing direction. When the content of LLDPE in the LLDPE/IPP blends is below 40%, epitaxial growth of LLDPE lamellae on highly oriented IPP lamellae has been observed. The intercrossing angle of the two kinds of epitaxial lamellae is about ±45℃, while the contact planes should be (010) of IPP and (100) of LLDPE. There is no above relationship of epitaxial crystallization in the films when the content of LLDPE in the blends is over 50% because of the formation of independent domain of LLD.PE. When the films of LLDPE/IPP blends was heat-treated at 135℃ (above the melting point of LLDPE) for 15 min, and subsequetly cooled to room temperature, the epitaxial relationship between LLDPE and IPP is maintained.