Experimental Characterization of Material Properties of Novel Silica/Polysiloxane Ablative

Abstract

This paper provides the details of the R&D of a new ablative material through a collaboration between The University of Texas at Austin and Techneglas LLC. The UHTR polysiloxane resin system is manufactured by Techneglas, based on a blend of polysiloxane chemistries. UHTR is used to fabricate silica fiber-reinforced composite materials by compression molding of prepreg. The objectives of this study are to process, fabricate, and experimentally characterize the physical, thermal, flammability, thermophysical, and ablation properties of the silica/UHTR composite. This silica/UHTR composite was compared with silica/phenolic fiber-reinforced polymers (FRPs) made in our lab as well as silica/phenolic (SC-1008) prepreg purchased commercially. The neat UHTR polysiloxane resin showed a higher char yield at 86.5% than the neat SC-1008 resin at 55.4%. Composites made from the UHTR resin showed exceptionally high char yields of 97.5, 96.7, and 95.8% for 35, 40, and 48 wt % samples, respectively. These composites showed superior recession rate, peak heat-soaked temperature, and mass loss rate during ablation testing using an oxy-acetylene test bed (OTB). Through-the-thickness thermal conductivity and specific heat capacity ranging from 50 to 600°C were measured using laser flash analysis and differential scanning calorimetry.