Preparation, characterization and fire resistance evaluation of a novel ceramizable silicone rubber composite

In order to improve fire resistance performances of sealant for pipe penetration, a novel ceramizable silicone rubber (CSR) composite was developed. The CSR composite was prepared by glass frits (GF), aluminum hydroxide (ATH), phosphorus-nitrogen flame retardant (NH2-C) as functional fillers to get a silicone rubber with reinforced char residues. The effects of ATH, GF, and NH2-C content on the mechanical and flame retardant properties were studied by orthogonal designed experiments. The scanning electronic microscopy and X-ray diffraction were used to characterize the microstructure and phase composition after the sintering test, and subsequently to explore the fire resistance mechanism of the CSR composite. Experimental results indicated the optimum composition of CSR (by weight percent) was 18% GF, 18% ATH, and 25% phosphorus-nitrogen flame retardant. The surface flammability and marine A class pipe penetration fire tests were untiled to evaluate the fire resistance of the CSR with optimal proportion. The results show the optimal CSR can achieve the A-60 grade in the pipe penetration fire test and possess superior low flame spread flammability. Its application in pipe penetration sealing would be an effective strategy to prevent the flame propagation.