Study was made of the compatibilization of polyethylene/polyamide 6 (PE/ PA6) blends with a ricinoloxazoline maleinate grafted polyethylene and styrene ethylene/butylene styrene copolymer. The blends were prepared in a twin-screw midiextruder, and the specimens for mechanical tests were injection molded with a miniinjection molding machine. The effect of compatibilizing on the mechanical properties and the morphology of the blends was studied. The toughness and ductility of the blends were substantially improved as a result of the compatibilization. Simultaneously, the strength and stiffness were slightly reduced. Morphological studies showed that the particle size was reduced and the adhesion of the dispersed phase to the matrix was improved by the compatibilization.

Oxazoline functionalized polypropylene, polyethylene, ethylene propylene copolymer (E/P), and styrene ethylene/butylene styrene copolymer (SEBS) were studied as compatibilizers in blends of polyolefins with polyesters and polyamides. The blends investigated were polypropylene/polyamide 6, polypropylene/polybutylene terephtalate, and polyethylene/polyamide 6, with engineering thermoplastic contents of 30 wt %. The blends were prepared in a twin-screw midiextruder, and injection molded with a mini-injection molding machine. The effect of compatibilizing on the morphology and mechanical properties of the blends was of interest. Compatibilization substantially improved the toughness of all tested blends. Their strength and stiffness remained at the level of the binary blends when polypropylene or polyethylene based compatibilizers were used, but slightly decreased with other compatibilizers. Morphological studies showed that the particle size was reduced, and the adhesion of the dispersed phase to the matrix improved by compatibilization. The effect of unfunctionalized polyethylene, polypropylene, E/P, and SEBS was also studied to compare the compatibilizers with them.

ABSTRACT:The aim of this work was to graft ricinoloxazoline maleinate (OXA) onto polyethylene (PE), and onto an ethylene propylene copolymer (E/P) and styrene ethylene/butylene styrene copolymer (SEBS), by melt free radical grafting in a twin-screw midiextruder. A study was made of the effects of the initial monomer and peroxide concentrations and of temperature on the degree of grafting, on the amount of residual monomer, and on the molecular weight. The initial monomer and peroxide concentrations were 1.5-9.0 wt % and 0.15-0.90 wt %, respectively. The grafting yield was found to increase with the initial monomer and peroxide concentrations. Grafting yields up to 2.1 wt % for PE, 2.3 wt % for E/P and 2.7 wt % for SEBS were achieved. The degree of grafting also varied considerably with the temperature. E/P and SEBS decomposed with low initial monomer and peroxide concentrations, but crosslinked with raising the initial concentrations. Polyethylene crosslinked even with low initial concentrations, but with a suitable choice of peroxide grafted polyethylene could be produced with good grafting yields and without gel formation.