Studies on a dicyanate containing four phenylene rings and polycyanurate blends. 2. Application of mathematical models to the catalysed polymerization process Ian Hamerton a, * , Alan M. Emsley a , Brendan J. Howlin a , Paul Klewpatinond a , Shinji Takeda b a Department of Chemistry (C4), School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK b Research and Development Strategy Office, Hitachi Chemical Co., Ltd, 48 Wadai, Tsukuba, Ibaraki 300-4247, Japan Received 4 July 2002; received in revised form 13 May 2003; accepted 5 June 2003 Abstract Selected blends of bis-4-(4-cyanatophenoxy)phenyl sulphone with a commercial dicyanate, 2,2-bis(4-cyanatophenyl)propane are analysed using differential scanning calorimetry (DCS) to examine the processes of the aluminium-catalysed thermal polymerisation. Kinetic treatment of these data show that the kinetics of the formation of the bis-4-(4-cyanatophenoxy)phenyl sulphone homopolymer were fitted with just two processes, but three processes were required for the 2,2-bis(4-cyanatophenyl)propane homopolymer, for which a more complex thermogram was obtained. When considering the polymerisation kinetics of binary blends of the monomers it was necessary to select the minimum number of kinetic parameters to obtain the best fits to the data. The binary blends generally show trends in the data that reflect the monomer composition. The parameters derived from two kinetic methods are broadly in agreement; the kinetic treatment of the thermal data for 2,2-bis(4-cyanatophenyl)propane monomer suggests the presence of at least one impurity and this is supported by spectroscopic and chromatographic analyses. The latter was not observed for bis-4-(4-cyanatophenoxy)phenyl sulphone, a monomer found to be of a higher purity by chromatography. From the kinetic analysis of the thermal data (from dynamic DSC), the mathematical model predicts that, following an isothermal cure regime at 450 K, bis-4-(4-cyanatophenoxy)phenyl sulphone should reach a conversion of 90% after ca. 33 min. The empirical data for this isothermal experiment show that bis-4-(4-cyanatophenoxy)phenyl sulphone reaches a conversion of 73% after 33 min and 87% after 2 h at 450 K. q 2003 Elsevier Science Ltd. All rights reserved. Keywords: Cyanate esters; Polycyanurates; Polymerization kinetics 1. Introduction Cyanate ester resins (polycyanurates) are a family of thermosetting resins that are used within a variety of technological applications. Cured polycyanurates offer high performance, including relatively high glass transition temperature (T g for AroCy B-10 is ca. 260 8C, depending on degree of cure), good fracture toughness (typically G IC ¼ 140 J m 22 for cured neat AroCy B-10 or 500 J m 22 when blended with poly(arylene ether sulphone) [1]) and low moisture absorption (polycyanurates typically gain less than 3 wt% in short-medium term conditioning studies). The combination of good thermo-mechanical and dielectric properties (e.g. dielectric constant, 1 ¼ 2:2 – 2:7 and dissipation factor, D f ¼ 0:003 at GHz frequencies) makes cyanate esters attractive competitors for epoxy resins and polyimides in many electronic (as well as adhesive and advanced structural composite) applications. Currently, the single largest application for polycyanurates is as lami- nation substrates for printed circuits and their assembly via prepreg adhesives into high-density, high-speed multi-layer boards, which are produced commercially for super- computers, mainframes and high speed workstation mother units [2]. In a previous paper we demonstrated the benefits of blending a commercial dicyanate with bis-4-(4-cyanatophe- noxy)phenyl sulphone by examining the thermo-mechanical properties (as evidenced by increases in thermal stability, modulus and glass transition temperature and reductions in thermal expansion behaviour). In this paper we examine the 0032-3861/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0032-3861(03)00495-6 Polymer 44 (2003) 4839–4852 www.elsevier.com/locate/polymer * Corresponding author. Tel.: þ 44-1483-259587; fax: þ 44-1483- 876851. E-mail address: i.hamerton@surrey.ac.uk (I. Hamerton).