Thermal polymerization of acrylamide by differential scanning calorimetry

Abstract

Thermal polymerization of acrylamide was studied by differential scanning calorimetry. Latent heat of fusion ΔH_f and enthalpy of polymerization ΔH_p values were found to be 36 and −18.0 kcal mol⁻¹, respectively. The overall activation energy E for the polymerization was calculated to be 19 k cal mol⁻¹ up to 60% conversion. The added free-radical inhibitor (benzoquinone) was found to desensitize the thermal polymerization of acrylamide suggesting the polymerization to be a free-radical type. The existing rate equation for the heterogeneous bulk polymerization in the presence of initiators has been modified for the thermally initiated bulk polymerization of acrylamide. The experimental overall E value was found to agree well with the calculated E value when considering only the propagation and termination steps, thereby suggesting the process to be similar to postpolymerization of acrylamide.