This work deals with the development of flexible syntactic foams based on silicone and hollow glass microballoons (HGMs) for potential application as a lightweight thermal cum vapor barrier in fire-protective ensembles. HGMs offer excellent thermal insulation and their inclusion into silicone leads to significant weight reduction, while improving the level of protection. Flexible silicone foams containing different types and loadings of HGMs were prepared and it was observed that high-density microballoons (K46) survived compression molding process, due to their superior crushing strength (6000 psi) as compared to K15 (300 psi). The specific quasi-static mechanical properties increased proportionally to the extent of loading. The inclusion of HGMs did not alter the curing behavior of silicone resin. Syntactic foams (40 HGMs) were coated onto glass fabric (GF) to prepare composites and thermal protective performance tests were performed to establish their effect on heat transfer. The protection level was higher for syntactic foam containing K46 glass microballoons, as compared to K15. The second-degree burn time increased from 6.4 s (neat GF) to 10s for syntactic foam-coated GF. Our studies demonstrate the potential of the developed syntactic foam-coated GFs as a vapor cum thermal barrier in fire protective clothing.
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