PP/EPR共混体系的相容性

COMPATIBILITY OF PP/EPR BLENDS

利用橡胶类聚合物二元乙丙(EPR)与聚丙烯(PP)熔融共混是PP常用的增韧改性手段。共混体系中PP连续相与EPR橡胶相分散成具有良好相界面作用的“海-岛”结构,EPR对PP的增韧机理主要是“银纹-剪切带屈服”理论。虽然EPR与PP都含有丙基,根据相似相容性原理,它们之间应具有较好的相容性。但是在实际的共混中,EPR在基体PP中的分散状态还要取决于共混的工艺条件。在相同的共混组成条件下,当PP与EPR具有相近的熔融粘度时,所制得共混物的形态结构较均匀。在PP／EPR共混体系中,加入增塑剂邻苯二甲酸二辛脂(DOP)后,部分DOP分散在PP／EPR两相界面上,可以降低两相界面的结合强度,而使共混物的强度降低;另外加入第三组份PE后的三元共混物,可以通过控制PP、EPR、PE的含量,使EPR起到PP和PE的相容剂的作用,使体系形成一种特殊的“棱-壳”结构。

EPR and the use of rubber-like polymer melt blending PP is a commonly used means of modification. In blends, PP and EPR scattered into a ＂seaisland＂ structure. The loughening meehanism is the ＂ silver-striped-shear zone yield＂ theory. The EPR and PP both contain n-pmpyl, according to the Similar Compatibility Principles, they should have a better compatibility. In actual blending, thc decentralization of EPR blends also dcpcnds on the processing conditions. Blending in the same conditions, if the PP and EPR bare the similar of melt-viscosity, the structure of blend systems will be more evenly. By adding plasticizers DOP in PP/EPR blend system, DOP can scattered in the twoiphase interface, the interface enengy can reduce, thus reducing the strength of the blends. Adding a third group PE, by controlling the content of PP, EPR and PE. EPR will play as the COlnpatibility agcnt of PP and PE. and the system can formed a special ＂core-shell＂ structure.