The effect of copolymer composition on the batch foaming dynamics of styrene/methylmethacrylate copolymers

Abstract

In this work, styrene/methyl methacrylate (St/MMA) copolymer particles were synthesized by suspension polymerization process with different copolymer compositions to study the visual batch foaming dynamics. The visualization system consisted of the self-sealing observation cell equipped to the pressure and temperature controller. The synthesized copolymer particles were impregnated by n-pentane, followed by recording of particle expansion. The cell structure of foams was studied by scanning electron microscopy. The effect of different foaming conditions on the expansion behavior of copolymers was examined. It was concluded that sorption pressure and temperature have contradictory effects on the foaming ratio of the synthesized copolymers at lower and higher sorption pressures, and the results were confirmed with the foams' cell structure. Furthermore, it was shown that, at different temperatures and pressures, the expansion behavior change dramatically with increasing of MMA content in the copolymer.

Effect of silica nanoparticles on the impregnation process, foaming dynamics and cell microstructure of styrene-methyl methacrylate copolymer/n-pentane foams

“…The composition of monomers in synthesized random copolymer was determined using H-NMR spectrum for which the calculation method was reported in our previous works. 3–5,37 The glass transition temperature of neat copolymer was determined through DSC analysis which was equal to 100.3°C. The main characterized parameters of synthesized St-MMA copolymer are represented in Table 2.…”

“…The styrene-methyl methacrylate random copolymer particles was synthesized through suspension polymerization of styrene (St) and methyl methacrylate (MMA) monomers with St/MMA feed ratio of 53/47 (Azeotropic composition) according to our previous studies. 3–5,36,37 Styrene and methyl methacrylate monomers were supplied by Dae-Jung Chemicals & Metals Co., and the other materials which used in copolymer synthesis were the same as in our previous works. 3–5,7,36,37 n-Pentane with 99% purity as physical blowing agent in foaming experiments and Tetrahydrofuran (THF) with 99% purity as solvent for nanocomposite preparation were provided by CARLO ERBA.…”

“…Each of these steps may have impact on the final morphology and properties of prepared foams. 3–8 Since the final microstructure of prepared foams is investigated using common methods such as scanning electron microscopy (SEM), an in-situ visualization system is needed to attain a deep understanding about foaming process. 4,5,9,10…”

“…3,36,37 Moreover, the expansion dynamics of these particles using n-pentane as blowing agent was examined and the effect of sorption pressure, temperature, and time on foaming process at different copolymer compositions was investigated. 4,5 However, in these studies, the observation of bubbles nucleation and growth was not possible and only final microstructures were studied using SEM micrographs. Moreover, in another study, the foaming dynamics (bubbles nucleation and growth) of thin polystyrene sheet (with thickness of 200 µm) was investigated using n-pentane as blowing agent.…”

The effect of copolymer composition, gas content, and temperature on the bubbles nucleation and growth of styrene–methyl methacrylate copolymer/n-pentane foaming process

“…In general, the foaming process involves three important steps: bubbles nucleation, growth, and stability. 4 –6 It is well-known that the cell density, cell size, cell size distribution, and foam density have important effects on the final property of prepared foam. Subsequently, a basic understanding of the relationships between the processing conditions and microstructure during foaming process (the number of nucleated bubbles and bubble size distribution) remains important to control the final microstructure of foams and consequently producing foams with high useful properties.…”