Effects of ambient-temperature curing agents on the thermal stability of poly(methylphenylsiloxane)

Two kinds of curing agents, triethanolamine and polysilazane (KH-CL), were used to make polymethylphenylsiloxne (PMPS) cured at room temperature. Their effects on the short-term and long-term thermal stability of PMPS are reported and discussed. The influences of the curing agents on the thermal degradation mechanisms of PMPS were studied by thermogravimetric analysis (TG), differential thermogravimetry (DTG) and Fourier-transform infrared spectroscopy (FTIR). The results indicate that both kinds of PMPS had higher short-term thermal stability than traditional heat-cured PMPS. For long-term thermal stability, the PMPS cured with KH-CL was much higher than the one cured with triethanolamine. The "unzip degradation" of PMPS was eliminated through the reaction between KH-CL and silanol groups, and then the thermal stability of PMPS was improved. However, it was initiated at a low temperature (about 300 degreesC) with catalysis by triethanolamine, and the thermal stability was decreased. (C) 2004 Elsevier Ltd. All rights reserved.