The relationship between cellular microstructure and the mechanical properties of styrene/methyl methacrylate copolymer‐silica nanocomposite foams prepared by a supercritical <scp> CO <sub>2</sub> </scp> blowing agent
Ehsan Salari, Mostafa Rezaei, Davoud Jahani, Ahmadreza Tabbakhi‐Mamaqani
Abstract
Abstract Styrene/methyl methacrylate (St/MMA) copolymer‐silica nanocomposite foams were prepared using supercritical CO 2 as blowing agent, and the relationships between their cellular microstructure and mechanical properties were investigated. The effects of nanosilica content, size, and surface chemistry on the foam's microstructure and properties were examined. Dispersion and distribution of silica nanoparticles with different surface chemistry in St/MMA copolymer nanocomposites were discussed. To determine the most suitable copolymer composition for incorporating silica nanoparticles, some operating conditions such as temperature and pressure were primarily examined to study their effects on the microstructure of resulting foams. In compressive mechanical properties of final foams, a considerably high value was obtained for the compressive strength of the foams of up to 9.5 MPa. The prepared low‐density (below 0.2 g/cm 3 ) St/MMA copolymer microcellular foams can be used in green lost foam iron casting processes. Highlights Styrene/methyl methacrylate copolymer‐silica nanocomposite foams were prepared via supercritical CO 2 . Foams' cell size was changed by changing silica nanoparticle surface chemistry and size. The uniform cellular microstructure was achieved by nanosilica size increment. Increasing nanoparticle size improved the foam's mechanical properties. Low‐density foams were achieved for potential application in lost foam casting.