Thermal Degradation Mechanism of Addition-Cure Liquid Silicone Rubber with Urea-Containing Silane

The reactive urea-containing silane, (gamma-diethylureidopropyl) allyloxyethoxysilane (DEUPAS), was synthesized by the trans-etherification reaction. The chemical structure was characterized by Fourier transform infrared spectrometry (MR) and H-1 nuclear magnetic resonance skectrometry (H-1 NMR). Subsequently, DEUPAS was incorporated into addition-cure liquid silicone rubber (ALSR) via hydrosilylation reaction. The thermal stability of the ALSR samples was investigated by thermogravimetry (TG) and thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR). When DEUPAS was incorporated, the temperature of 10% weight loss and 20% weight loss under air atmosphere were respectively increased by 31 degrees C and 60 degrees C compared with those of the ALSR without DEUPAS. Meanwhile, the residual weight at 800 degrees C increased from 33.5% to 58.7%. It was found that the striking enhancement in thermal stability of the ALSR samples was likely attributed to the decomposition of the urea groups to isocyanic acid, which reacted with hydroxyl groups to inhibit the unzipping depolymerization. (C) 2015 Elsevier B.V. All rights reserved.