There is intense commercial interest in multiphase polymer blends because of the potential opportunities for combining the attractive features of several materials into one, but these blends have poor mechanical properties and unstable morphology. In this study Medium density polyethylene(MDPE( grafted glycidyl methacrylate (GMA) has been synthesized and applied for compatibilization of MDPE/polyamid6 (PA6) and MDPE/poly(ethylene terephtalate) (PET) blends. Grafting of GMA onto MDPE have been done by two different methods, molten state and solid state grafting. For the first time in this study solid state grafting of GMA onto MDPE have been performed using supercritical carbon dioxide (SCCO2). Grafting yield of 91% in molten state and 96% in supercritical condition has been achieved. Mechanism of styrene comonomer on grafting reaction has been studied and it's found that presence of styrene elevates copolymerization ceiling temperature and prevents depolymerization of grafted GMA monomers. It seems that styrene comonomer in supercritical method isn’t as effective as molten state because of low reaction temperature of this method. Four samples coded as C1, C2, C3 and C4 have been applied to compatibilizing of blends. Effect of compatibilizers on mechanical, rheological and morphological properties of the blends has been studied by tensile test, torque-time measurement and SEM studies. The results indicated that presence of compatibilizers in blends leads to 60% and 250% increase in torque and elongation at break respectively, also diameter of dispersed phase particles was a quarter of particle diameters in uncompatibilized blends. Furthermore, processing effect on blends properties have been studied in this project, it’s found that sample prepared with mono screw extruder are poor in morphological and mechanical properties because of bad dispersion and distribution of the extruder and it's not convenient apparatus for preparation of mentioned alloys.
