Investigation of Structure-Property Relations in Systematic Series of Novel Polymers

摘要

Thermomechanical spectra, from -180C to +630C (at a heating rate of 2C/min below 25C and 3C/min above 25C) were generated for the polycarboranesiloxane polymers Dexsil 300 and Dexsil 202 in nitrogen. Thermomechanical experiments were also conducted, from room temperature to 630C in air for both uncured and cured specimens. From the mechanical spectra, separation of the high-temperature thermal and oxidative effects was possible. This work suggested that the last step of the cure cycle proposed for Dexsil 202 is at the threshold of the temperature range corresponding to rapid mechanical changes. The cure cycle needs to be thoroughly investigated. The present data for the polycarboranesiloxane polymers were generated using a newly developed torsional pendulum. A two-component poly(metal phosphinate) system displayed extensive hysteresis in mechanical behavior throughout the temperature range -180C to >300C. Thermal preheatment to about 400C (the limit of thermal stability) eliminated these instabilities. (Author)