F-C烷基化反应原位增容PS/POE共混物中降解的抑制和增容效果的优化

在聚苯乙烯(PS)/聚烯烃弹性体(POE)/AlCl3共混物中引入苯乙烯(St)单体,增加了共混体系中的不饱和结构,AlCl3催化剂与St反应生成大量的初始碳正离子,这些初始碳正离子进攻POE链生成更多的大碳正离子,进而形成更多的PS-graft-POE共聚物,提高了接枝效率.进而,采用"两次挤出"技术,即先原位增容制成接枝母料,然后接枝母料再与PS和POE二次挤出,可以在一定程度上缓解组份的降解,使共混物的力学性能得到进一步的改善.

DEGRADATION CONTROL AND PROPERTIES OPTIMIZATION OF in situ COMPATIBILIZED PS/POE BLENDS BY FRIEDEL-CRAFTS ALKYLATION REACTION

in situ Compatibilization by Friedel-Crafts alkylation reaction has the commercial potential in the recycling of commingled post-consumed polymers containing polystyrene (PS) and polyolefin.The most important problem in the approach of in situ compatibilization of PS/POE (polyolefin elastomer) blends is to increase the efficiency of grafting and limit the degradation of the blending components.In order to increase the efficiency of grafting,the styrene (St) monomers were added into the in situ compatibilized PS/polyolefin elastomer (POE) blends.The graft degree of PS/POE/St/AlCl₃ (80/20/n/0.8,wt%) increased from 8.6% to 14.0% with the St content increased from 0 to 0.6%,indicating that the addition of St could accelerate the Friedel-Crafts alkylation reaction.The St/AlCl₃ catalyst system initiated more PS-graft-POE copolymers than the single AlCl₃ catalyst.Because those PS-graft-POE copolymers acted as the compatibilizers between the interface of PS and POE,the mechanical properties of PS/POE blends were greatly improved.For example,the Charpy impact strength increased from 8.5 kJ/m² to 9.9 kJ/m² and the elongation at break increased from 22% to 29% when 0.6% St was added to PS/POE/AlCl₃ (80/20/0.8,wt%) blend.Besides,the two-step extrusion procedure gave better mechanical properties of PS/POE blends,which were the results of a limitation of degradation of blending components when the master batch product and virgin polymers were extruded in the second extrusion step.