Ceramifiable Silicone Rubber Composites with Enhanced Self-Supporting and Ceramifiable Properties

Ceramifiable silicone rubber (SR) composites with excellent self-supporting properties and ceramifiable properties were prepared by incorporating silicate glass frits (SGFs) and sodium tripolyphosphate (STPP) into the SR. Ceramic residues were obtained by firing ceramifiable SR composites at 700, 850, and 1000 °C for 30 min. The bending angles of the composites were tested for evaluating the self-supporting property. To evaluate the ceramifiable properties of the ceramifiable SR composite, flexural strength, water absorption, and bulk density of its residues were tested. It was found that the addition of STPP improved the shape stability and the self-supporting property of the composites at high temperatures. The flexural strength of the ceramic residue of the composite with STPP firing above 850 °C is more than 5 MPa. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis showed that the relative content of the crystalline phase was enhanced by about 25% due to the addition of STPP. Furthermore, a possible mechanism for the formation of the crystalline phase was proposed. Scanning elector microscope (SEM) and energy dispersive spectrometry (EDS) analysis demonstrated that with the temperature increase, the inter-infiltration between these melts became easier, which implies that the bulk density of the ceramic residue was improved.