The effect of expansion conditions on the batch foaming dynamics of St-MMA copolymer

In this study, we synthesized styrene-methyl methacrylate copolymer particles by suspension polymerization process to study the foaming dynamics via visual batch foaming apparatus. The weight ratio of styrene-methyl methacrylate was 53-47. The foaming system consisted of a self-sealing observation cell equipped with two glass windows and a stereo microscope attached with a high-speed digital camera as well as a pressure and temperature controller. The required pentane pressure was supplied by heating a small pentane flask. The synthesized copolymer particles impregnated by pentane and then the foaming dynamics were recorded after a rapid pressure release. The effect of different foaming conditions, such as temperature, impregnation time, and impregnation pressure on the expansion ratio of styrene-methyl methacrylate copolymer was investigated. It was concluded that impregnation pressure, time, and temperature have different effects on the foaming ratio at impregnation pressures lower and higher than 4 bar.