Structures and morphologies of in situ polymerized blends of PMMA and ASA

Blends of poly(methyl methacrylate), PMMA, and the elastomer ASA, a graft copolymer based on poly(acrylonitrile‐co‐styrene) (SAN) and acrylic rubber, were prepared by in situ polymerization and characterized according to structural, mechanical, thermal, and morphological properties. The polymerization conditions, such the presence or absence of a chain transfer agent, stirring and an inert atmosphere, influence the morphological and structural properties of the blends. In spite of the evidences of the partial miscibility between PMMA and SAN phase of the ASA, the blends are heterogeneous and present a complex morphology. The morphology of some PMMA‐ASA blends is made up of an elastomeric dispersed phase in a glassy matrix, with a possible inclusion of the matrix in the elastomeric domains. The selective extraction of the blend components and infrared spectroscopy showed that crosslinking and/or grafting reactions occur on ASA chains during MMA polymerization. The syndiotacticity of PMMA obtained in the presence of ASA increases with the amount of ASA, due to possible interactions between the carbonyl groups of PMMA and the nitrile or phenyl groups of the SAN copolymer. The mechanical properties of the blends were influenced by the compositions of the blends and mainly by the conditions of polymerization. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013