Preparation and Characterization of Poly(Lactic Acid)-g-Maleic Anhydride[thinsp]+[thinsp]Starch Blends

Poly(lactic acid) (PLA) and starch copolymers are obtained by reactive blending varying the starch compositions from 0 to 60%. PLA is functionalized with maleic anhydride (MA), obtaining PLA-g-MA copolymers using dicumyl peroxide as an initiator of grafting in order to improve the compatibility and interfacial adhesion between the constituents. PLAþ starch blends without a compatibilizer do not have sufficient interfacial adhesion. Decomposition temperature of PLA is not affected by grafting. Glass transition temperatures and dynamic mechanical properties are affected since MA has a plasticizing effect. Along with an increasing starch content friction decreases while wear loss volume in pin-on-disk tribometry has a minimum at nominal 15% wt. starch but increases at higher starch concentrations. The residual depth in scratching and sliding wear testing has a maximum at 15% starch; there is a minimum of storage modulus E0 determined in dynamic mechanical testing at the same concentration. Microhardness results also reflect the plasticization by MA.