Possible Mechanism for Increasing the Fire Resistance of a Polymer Coating Filled with Diatomaceous Biosilica

Abstract

It has been proposed a new mechanism for increasing the themal and fire resistance of polymer coating. Contrary to a known barrier mechanism for increasing the fire resistance of polymers which is characteristic for fillers in the form of plates or scales, the new mechanism is proposed for filler in form of flakes. This filler prevent the oxygen diffusion into polymer and hinder the transport of gaseous products of pyrolysis. Particles of diatomic biosilica (shells of algae) are micro-containers with a diameter of ~ 4 μm. Individual shell flaps, which are similar in shape to a Petri dish, are perforated with an ordered system of pores 150-200 nm in diameter. The filler serves as a natural sink for combustible decomposition products. If the average distance between the particles is less than the thickness of the sample, then the primary sink for combustible gases will be not the film surface, but the filler particles, which play the role of a flame retardant.