Improvement of polyolefin film by alternately stacking different kinds of thin, oriented polymers

点击翻译按钮获取中文摘要

The composite films in which oriented isotactic propylene (iPP) and polyethylene (PE) were alternately stacked in layr were prepared, but their physical properties such as tensile modulus and strength were not high enough to be endurable in practical use. To improve the properties, we found there are three main hurdles to overcome.Firstly, it is needed that respective layrs of iPP and PE are as thin as possible, maybe their single layr is less than 0.1 mm before drawn. In the present study, a stacked film was prepared by piling alternately the so-called 'gels' of iPP and PE which were made by crystallization these polymers from solution. When gels of iPP and PE were alternately stacked, surfaces of respective gels were rather rough, and hence it was very difficult to make the thickness of individual layrs uniform, especially when each layr was thin. A technique to make individual layrs thin and their surface flat must be developed.Since tempertature where high draw-ratio can be achieved differs between iPP and PE,it was problem to choose an appropriate temperature to draw them highly at the same time. From the present results, it was found that both polymers were smoothly drawn at the same time in the temperature range of 130ﾟC-140ﾟC.Selection and control of an appropriate drawing temperature are the second problem to be solved.Another issue to be overcome is to draw highly the stacked gel-film thus prepared. This is closely related to the above two issues.