Enhancement of Mechanical Properties of Emulsion Copolymers by Gradual Variation in Feed Composition. I: Effect of Particle Size in the Butyl Acrylate-Styrene System

Using a semicontinuous seeded emulsion polymerization process with a gradual variation in feed composition, butyl acrylate (BA)/styrene copolymers were obtained (variable composition copolymers, VCCs). BA seed particles of two different diameters were used to prepare copolymer materials with 50-85 wt.% styrene. In each reaction, cumulative copolymer composition was followed by 1H-NMR; with such data, a histogram showing the relative content of copolymer chains corresponding to each composition interval was built. The VCCs presented higher moduli and ultimate mechanostatical properties than their equivalent core-shell type polymers. The mechanical performance of VCC materials was explained considering the respective histograms. ® 2012 Copyright Taylor and Francis Group, LLC