Effects of compatibilizers on the flexural properties of grass straw-polyethylene composites

A number of grass straw-polyethylene composites were fabricated using Oregon rye grass (Lolium spp.) straw, high density polyethylene, and a number of compatibilizers: poly(diphenylmethane diisocyanate), maleic anhydride-modified polyethylene, stearic acid, and combinations of them. Grass straw-polyethylene composites with one of the previously mentioned compatibilizers had a higher modulus of rupture and modulus of elasticity than those without a compatibilizer. Combinations of poly(diphenylmethane diisocyanate) and one of the other compatibilizers resulted in a higher modulus of rupture and modulus of elasticity than poly(diphenylmethane diisocyanate) alone. The greatest improvement in modulus of rupture and modulus of elasticity as well as the lowest water uptake were observed in the composites containing a mixture of stearic acid and poly(diphenylmethane diisocyanate). Scanning electron microscopy showed the compatibilizers improved the interfacial adhesion of the resultant grass straw-polyethylene composites.