Properties and morphology of nanocomposites based on styrenic polymers, Part II: Effects of maleic anhydride units

Based on enhancement in exfoliation for polyolefin-g-maleic anhydride composites with the addition of as little as 1 wt% maleic anhydride (MA), the effect of MA in styrene-maleic anhydride copolymer (SMA)-based nanocomposites was studied. SMA nanocomposites were mixed using a DSM melt compounder followed by injection molding in a pneumatic bench top molder. These materials produced the same modulus enhancement and TEM-based areal particle densities on a weight percent basis as SAN-based nanocomposites from a previous study, but the areal TEM-based particle densities remained lower overall than literature values for polyolefin-g-MA mixtures. This behavior is explained by repulsive interactions between styrene and the alkyl tail of the surfactant, suggesting that polar surfactant tails could lead to improved exfoliation in styrene copolymer-based/montmorillonite nanocomposites. The role of increased melt viscosity and shearing on particle dispersion as MA is added to the copolymer is discussed.