Expandable Styrene/Methyl Methacrylate Copolymer: Synthesis and Determination of VOCs by Combined Thermogravimetry/Differential Thermal Analysis-Gas Chromatography/Mass Spectrometry E. Haddadi, 1 E. Mehravar, 2,3 F. Abbasi, 2,3 K. Jalili 2,3 1 Technical Higher Education Center of Tabriz, Tabriz, Iran 2 Institute of Polymeric Materials, Sahand University of Technology, Tabriz, Iran 3 Faculty of Polymer Engineering, Sahand University of Technology, Tabriz, Iran Received 30 April 2011; accepted 22 August 2011 DOI 10.1002/app.35513 Published online 6 December 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Parts cast of metals using expandable poly- styrene foams may have an unacceptable amount of surface defects, such as lustrous carbon. The use of foams made of styrenic/acrylic copolymers can improve the quality of foam molds and metal parts made using such molds. Lost foam copolymer was synthesized by suspension copolymer- ization of styrene and methyl methacrylate. The polymeriza- tion was carried out in the presence of blowing agents. The decomposition products of lost foam beads were studied by a method composed of the thermogravimetry/differential thermal analysis (TG/DTA) and gas chromatography/mass spectrometry (GC/MS). With these systems, the TG/DTA data can be combined with a GC separation and MS identi- fication methods. This combined method improves the anal- ysis of the decomposition products of lost foam beads and enables the precise identification of the amount and the na- ture of volatile organic compounds (VOCs) trapped during suspension polymerization. The results obtained from the combined method were verified for the nature and amount of VOCs with the results of time-conversion studies for copolymerization of monomers in the presence of different concentrations of blowing agent. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 4711–4720, 2012 Key words: suspension polymerization; expandable copolymer; blowing agent; TG/DTA-GC/MS analysis INTRODUCTION Styrenic polymers have a wide variety of applica- tions, including the formation of expandable poly- styrene (EPS) particles, which can be used to make a variety of products. Processes for forming styrenic polymer particles include emulsion polymerization, suspension polymerization with accompany of par- ticular suspensions or emulsion aids. EPS foams and other expanded resins can be prepared from ex- pandable polymeric particles made by contacting the polymeric beads with a volatile compound known as a ‘‘blowing agent’’ or ‘‘expanding agent.’’ Such agents include aliphatic hydrocarbons such as bu- tane, pentanes, hexanes, and halogenated hydrocar- bons such as trichloromethane, trichlorofluorome- thane, and methyl chloride. 1–12 The particles in contact with the expanding agent may be expanded by heating or by exposure to reduced pressure as in a vacuum. The size and size distribution of the ex- pandable particles (compact particles) influence the size and size distribution of the particles after expansion. Both the expanded and expandable polymers have applications in packaging, consumer products, and in materials processing. Examples of materials’ proc- essing applications for expanded polymers include so-called lost foam or evaporating pattern casting (EPC). In lost foam casting, a molten metal is poured into a pattern made of expanded polymeric material, that is, foam coated with a refractory material sur- rounded and supported by unbounded sand. The foam is decomposed by the heat of the molten metal and replaced by the metal. 13–16 In recent years, an EPC technology is increasingly used in casting technology, which is a new tech- nique without residuals and with excellent molding accuracy. In this method, a readily volatizable foam is used as mold pattern and it is unnecessary to take out the mold. Therefore, any mold joint and any sand core are eliminated. The dimensional accuracy and the surface roughness of the metal parts pro- duced by this method are comparable with the ones in the investment casting. 17,18 Because of possibility of carbon pickup, the process using EPS patterns is Correspondence to: F. Abbasi (f.abbasi@sut.ac.ir). Journal of Applied Polymer Science, Vol. 124, 4711–4720 (2012) V C 2011 Wiley Periodicals, Inc.