Flame Retarding of Wood by Chemical Modification with Bromate-Bromide Solutions

Abstract

In spite of the extensive and diversified uses of wood and wood products for millenia, there are still a number of basic deficiencies of these products which limit their use and pose difficult and as yet not satisfactorily solved problems to the engineer and consumer. The most prominent of these problems are: flammability, dimensional stability, and fungal attack. Review of work carried out at the Israel Fiber Institute indicates that treating solid timber and polywood with acidified bromate-bromide solutions is capable of overcoming these deficiencies to a large extent. The treatment is carried out in autoclaves with application of vacuum and pressure. The lignin component of the wood is brominated in the solid state by the treatment solution with a high yield of bromine. The mechanical properties of the treated products are unchanged. The treatment is stable to prolonged leaching, aging, and storage. Water absorption and swelling are drastically decreased-dimensional stabilization. The brominated products are shown not to be attacked by wood fungi.

Synergism and catalysis in flame retardancy of polymers

“…phosphorus, nitrogen and a polyhydric alcoholcotton resemble an intumescent system the SE is much lower. A similar SE of 1.6 is also obtained when treating wool with sulfamic acid and urea as a synergist [32].…”

Natural polymers, wood and lignocellulosic materials

“…In Egypt, 3000 years ago, reed and grass were soaked in sea-water before being used for roofing purposes. Comprehensive reviews of fire retardants were also published by Brahmhall, 20 Juneja, 21 Lewin 22,36 and others. In ancient Roman times, a fire retardant was described by Aulus Gellius.…”

“…due to fungi), but also leads to the destruction of metal joints and building elements. [36][37][38] Most of the reactive fire retardants are based on bromine, fluorine and chlorine compounds such as, for example SF 3 Br, CH 2 BrCl, CF 2 BrCl, CF 2 Br 2 , CF 2 Br-CF 2 Br, although they are very toxic. Boric acid acts as the inhibitor of flame and smoke formation.…”

Combined Fire Retardant and Wood Preservative Treatments for Outdoor Wood Applications – A Review of the Literature

“…Lewin, whilst at the Israel Fiber Institute in Jerusalem investigated the bromatebromide process and found that this method was capable of achieving a high level of fire retardance [32]. The wood treated in this study was Southern Yellow Pine and Spruce, and the process involved the direct bromination of the lignin with an acidified bromate-bromide solution.…”