反应挤出共混法制备高熔体粘度聚丙烯的研究

Research on Modified PP With High Melt-Strength Made by Reaction Extrusion and Blend Method

采用反应挤出共混聚丙烯(PP)和低密聚乙烯(LDPE)制备高熔体强度的改性PP,并加入过氧化二异丙苯(DCP)和共单体,来引发、促进体系的交联并抑制PP的降解。通过熔融指数和凝胶质量分数确定由交联和降解引起的流动性能的变化。研究发现:共混后,熔融指数明显降低且有凝胶产生,熔体流动速率可降低至0.5g/10min以下,凝胶质量分数可高达30%以上。这表明体系中发生明显的交联;当LDPE质量分数低时,体系以PP的降解为主,当LDPE质量分数超过28%时,交联占据主导地位;且随着引发剂DCP质量分数增加,体系交联程度增加。

Using reactive extrusion, modified polypropylene (PP) with high-melt strength was made.by blending PP with low-density polyethylene (LDPE). Adding the oxide initiator of dicumyl peroxide (DCP) and the crosslinking coagent is to initiate and to promote the crosslinking of the system, and to restrain the degrading of PP. Melt rheologic action of the material is studied by analyzing the change of melt index (M7) and gel content. It is observed that there were gel which can get over 30 % in the system and obvious reduction of MI which can be lower than 0. 5 g/10 min, all of these surely proved the crosslinkage in the blending process. There was chain degradation of PP with low content of LDPE in the system, whereas the crosslinkage plays a leading role when the content of LDPE is over 28%, and also the degree of crosslink-age increases with the increase of the content of the initiator.