Free radical terpolymerization of butyl acrylate/methyl methacrylate and alpha methyl styrene at high temperature N.T. McManus, G. Hsieh, A. Penlidis * Department of Chemical Engineering, University of Waterloo, Waterloo, Ont., Canada, N2L 3G1 Received 5 December 2003; received in revised form 17 May 2004; accepted 24 May 2004 Available online 7 July 2004 Abstract The free radical initiated terpolymerization of butyl acrylate (BA), methyl methacrylate (MMA) and alpha methyl styrene (AMS) has been examined. Kinetic studies focused on elevated reaction temperatures (115 and 140 8C). The studies were made over the full conversion range and examined the effect of reaction temperature, feed composition and initiator level on reaction rates. The composition of terpolymer products and their molecular weights were also analyzed with respect to monomer conversion levels. q 2004 Elsevier Ltd. All rights reserved. Keywords: Terpolymerization; Butyl acrylate; Methyl methacrylate 1. Introduction Free radical polymerizations are used in many commer- cial polymerization processes partly because the process technology is robust and can be applied to a great range of monomers. This means that the method offers great flexibility in relation to the production of multi-component polymers. The range of monomers to which the technique can be applied and the fact that polymer composition in free radical processes can be adjusted by variations in reaction conditions offers the possibility of an almost infinite range of product compositions. As a result of this, the preparation of multi-component polymers is a well-established method for producing polymers with specific physical and chemical properties. Strategies to make such polymers are the key to development and improvement of, for instance, coating formulations. Currently, a key motivating factor in coatings technology is the production of high solids coating systems [1]. In order to prepare such polymers, resins with low molecular weights and narrow molecular weight distri- butions are required [2]. A possible option for producing low molecular weight polymers is to carry out the reaction at higher temperatures. Such a strategy will also lead to faster reactions and also dissipate the effects of autoacceleration. AMS as a monomer offers some process advantages under these circumstances because of its propensity to retard polymerizations; it can therefore be used to moderate reaction rates. In addition, the monomer chain transfer constant for AMS is high and thus molecular weight development in bulk polymerizations of AMS is dominated by chain transfer to monomer [3]. This makes AMS potentially useful in the manufacture of multi- component oligomers (or low molecular weight polymers) because in practical terms its presence can circumvent the need for additional chain transfer agents. Another practical use for AMS in multicomponent polymers arises from the high T g of AMS polymers, thus its incorporation into multicomponent systems increases the effective operating temperature range for resulting products [4]. The long term systematic study of the multi-component polymerization comprising BA, MMA and AMS has been undertaken over a wide range of temperatures (60 – 140 8C). The major objective of the work was to study the individual parts of the system to provide a database for use in modeling the system [5]. The primary stages of the study looked at the copolymerizations of BA/MMA, MMA/AMS and BA/AMS [6–8]. These investigations examined first low conversion copolymerizations to assess temperature effects with respect to copolymer composition models developed to account for the presence of depropagation. Full conversion range polymerizations were used next to assess how high 0032-3861/$ - see front matter q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymer.2004.05.077 Polymer 45 (2004) 5837–5845 www.elsevier.com/locate/polymer * Corresponding author. Tel.: þ1-519-888-4567x6634; fax: þ 1-519- 746-4979. E-mail address: penlidis@cape.uwaterloo.ca (A. Penlidis).