Synthesis and expansion characteristics of expandable styrene/methyl methacrylate copolymer beads: The effects of monomer composition and cell structure modifying aid

Abstract

Parts cast of metals such as iron, using expandable polystyrene foams, may have an unacceptable amount of surface defects, such as lustrous carbon. The use of foams made of styrene/methyl methacrylate copolymers can improve the quality of foam molds and metal parts made using such molds. In this work, expandable copolymers were synthesized by suspension copolymerization of styrene and methyl methacrylate in the presence of blowing agents (pentane isomers). When the surrounding temperature was high enough to vaporize the blowing agent and soften the polymer shell, the beads were expanded. The effects of monomer composition and cell structure modifying aid (polyethylene wax) on the particle size, average molecular weight and molecular weight distribution of synthesized copolymer, pentane content and expansion properties (density, residual pentane of pre-expanded particles and cell structure) were investigated. The results showed that monomer composition had a significant effect on the copolymerization kinetic and the copolymer molecular weight. In addition, cell structure, cell size and cell size distribution of the pre-expanded particles were strongly influenced by cell structure modifying aid concentration. The effects of comonomer composition and copolymer particle size on pentane content of expandable particles were also studied.

Synthesis of core-shell PS/PMMA expandable particles via seeded suspension polymerization

“…3) comparing with the morphologies developed upon synthesis of the bead consisting from a random poly(St-co-MMA) [17] or PS/PMMA core/shell [3]. The morphologies depicted in Fig.…”

Fabrication of methyl methacrylate-based polymer particles by miniemulsion and combined miniemulsion/emulsion polymerization using an atomization apparatus

“…The interest in the manufacture of MMA-based copolymers arose to overcome the deficiencies of PMMA in terms of thermal resistance (Kim et al 2015;Zhang et al 2015). The literature has proposed a series of polymerization methods for obtaining styrene-methyl methacrylate copolymer (STMMA) (Jalili et al 2011;Vaganova et al 2011;Mehravar et al 2012). However, to our knowledge, there are no reports of the synthesis of this copolymer by combined miniemulsion/emulsion polymerization using an atomization apparatus.…”

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

“…More details of the copolymerization procedure have been published in our previous works. 1,27,28 Copolymer characterization Particles composition was determined by proton nuclear magnetic resonance ( 1 H NMR) spectroscopy. The particles were dissolved in deuterated chloroform, the spectra of the samples were obtained using a Bruker Avance DPX NMR spectrometer (Billerica, Massachusetts, USA) working at 500 MHz.…”

“…In DSC endotherms of St/MMA copolymers, in the curves, the first inflection of heat flow versus temperature was selected as a T g of the sample. 28 SEM (VEGA series, TESCAN, Czech Republic) was used to study the cell structure of foamed copolymer particles. All the samples were coated with a thin layer of gold before SEM examination.…”