Reactive compatibilization of maleated polypropylene and maleated poly(styrene‐b‐butadiene‐b‐styrene) blends

Blends of maleated polypropylene with maleic anhydride (PP–MAH) and maleated styrene–butadiene–styrene triblock copolymer with maleic anhydride (SBS–MAH) were compatibilized with 4,4′‐diaminediphenylmethane, at various concentrations, as the coupling agent for the functionalized polymers. Their properties were compared with those of the corresponding blends of PP–MAH and styrene–butadiene–styrene triblock copolymer. The blends containing 15 and 50 wt % elastomers were prepared in a mixer at 190°C and 55 rpm. Torque measurements and solubility tests suggested a graft copolymerization during the melt blending of PP–MAH and SBS–MAH. Infrared spectroscopy was used to characterize the graft copolymer formed during the melt blending of the maleated polymers. The blends presented a morphology of a disperse elastomer phase in a continuous PP–MAH matrix. The size of the elastomeric domains decreased as the diamine and anhydride molar ratio increased.