Foams fire behaviour

It is nearly 20 years ago that the unacceptable fire behaviour of "modern" upholstered furniture became highlighted in the UK by Fire Brigade reports of domestic fires. This poor performance was blamed on the use of flexible polyurethane (PU) foam upholstery and demands were made to ban PU foam or at least to insist on the use of flame retarded PU foam. 

The polyimide foams are flexible and have a very low density (7 kg/m ), associated with good fire behaviour, a broad service temperature range and good soundproofing and thermal insulation qualities. These materials are sensitive to diluted strong bases, concentrated salts and acids. Other foams have densities varying from 15-250 kg/m. ... 

Bastin, B. Lefebvre, J. Paleja, R. Fire behaviour of polyurethane foams. Book of Abstracts, Proceedings of Polyurethanes Expo 2002, Salt Lake City, UT, October 13-16, 2002 American Plastics Council Washington, 2002 pp. 244—254. 

Modesti, M. Lorenzetti, A. Besco, S. Hrelja, D. Semenzato, S. Bertani, R. Michelin, R.A.. Synergism between flame retardant and modified layered silicate on thermal stability and fire behaviour of polyurethane nanocomposite foams. Polym. Degrad. Stab. 2008, 93, 2166-2171. 

Modesti, M. Lorenzetti, A. Improvement on fire behaviour of water blown PIR-PUR foams Use of an halogen-free flame retardant. Eur. Polym. J. 2003, 2, 263-268. 

Rigid polyurethane foams - Temperature stability up to 250 °C, fire behaviour studied [58]... 

Polyisocyanurate - PU foam Expandable graphite Fire behaviour of this foam considerably improved by use of expanded graphite [59]... 

TEP-EG filled PU foams [65] showed an overall improvement of their fire behaviour, the LOI increasing and the RHR decreasing with increasing filler content. The best fire performance was obtained using TEP and EG in a synergistic combination. 

Realinho, V., Haurie, L., Antunes, M., Velasco, J.I. Thermal stability and fire behaviour of flame retardant high density rigid foams based on hydromagnesite-filled polypropylene composites. Compos. B Eng. 58, 553-558 (2014)... 

The fire behaviour of polymer foams is largely dependent on their exposure to air and is dominated by the characteristic low thermal inertia which permits the surface to respond very rapidly to any imposed heat flux and consequently ignition maximum rates of burning can be achieved very quickly. Approaches toward reducing the flammability of polymer systems, in general, can be grouped in several categories [25,142,155-176] ... 

The presence of ammonium polyphosphate and melamine cyanurate filler causes a slight worsening of the physical and mechanical properties of PU and PIR foams but the fire behaviour of flame retarded foams is better than that of unfilled foams. In particular the use of the previously mentioned mixture, which produces a synergistic effect causes a significant improvement of the fire performance. This is characterised by a remarkable decrease of RHR and weight loss without worsening smoke opacity and toxicity [183]. 

It has proved difficult to determine any correlation between the test result of the various national procedures [53]. Because of this, the experts of TC92 of the International Standards Organisation (ISO) have undertaken the development of a test procedure to characterise independently ignitability, flame spread, rates of heat release, and other fire-related parameters [54-56]. Worldwide efforts continue to correlate laboratory tests to real-life fires [57]. Examples of such programmes are the corner test programme carried out by Factory Mutual and the corrugated metal tool deck [58] trials [59, 60] carried out by TNO. The corner test has been used to determine the fire behaviour of rigid foam materials when exposed to severe wood crib fire. 

There was no clearance between the core and skin in the tested sandwich pieces, which is an important factor in upgrading the flammability behaviour. Any material used in the manufacture of sandwich panels must be at least as fire resistant as the skin and core materials. For example, when phenol/formaldehyde foam cored sandwich elements were mounted on firwood frames, the flames were conducted by the frame, thus enhancing the fire risk. 

Full-scale fire tests can give more useful information than small-scale tests with tiny specimens. They can simulate the behaviour of plastics articles such as foam-filled furniture and television sets in fires. Examples include the Steiner tunnel test, the ISO 9705 room comer test and the CAL 133 test. Many fire test procedures are specific to a given industry, such as construction or the railways. In the latter case, the standard of flammability required may depend on whether a train is to be operated through long tunnels. 

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