Analysis of DSC curve of dodecyl methacrylate polymerization by two-peak deconvolution method

Abstract

Free radical polymerization of n-dodecyl methacrylate (DDMA) in bulk has been investigated by differential scanning calorimetry (DSC). Autoacceleration of reaction was observed at the temperatures 70, 80, and 90 °C, with 0.25, 0.5, and 1 wt% of initiator, and was absent at 100 °C. DSC curves obtained at the temperatures below 100 °C were characterized by two maxima. Two-peak deconvolution was used to separate DSC curve into two constitutive unimodal curves, i.e., to calculate the contribution of polydodecyl methacrylate formed before (first maximum) and after (second maximum) the onset of autoacceleration. The share of second maximum decreases as the polymerization temperature and initiator concentration are increased. As the organization of monomer is known to decrease with increasing temperature, it can be expected that the fraction of polymerized disordered phase of monomer (first maximum in DSC curve) is the highest at 90 °C. Our results confirm this prediction and are in good agreement with those observed from conversion versus time curves of DDMA polymerization. © 2009 Akadémiai Kiadó, Budapest, Hungary.