Relationship Between Chemical Structure and Flammability Resistance of Polyurethanes

Frisch, K. C.; Reegen, S. L.

doi:10.1007/978-1-4684-2148-4_7

Cited by 8 publications

(3 citation statements)

References 25 publications

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“…Isocyanates will undergo selfaddition to give cyclic structures, as illustrated below, and these are known as isocyanurates: The inclusion of isocyanurate rings in a foam was found to bring about a notable improvement in fire behaviour, and to lead to an increase in the limiting oxygen index. 45 It was pointed out earlier that one of the important features of the fire behaviour of polyurethanes is that they burn with very smoky flames. There have been attempts to suppress this feature, for example, by incorporating ferrocene or selected phosphorus derivatives into foams as additives which seem to function either by improving the efficiency of oxidation, or by encouraging preferential c h a r -f~r m a t i o n .~~ Additives, such as ferrocene, which appear to improve the efficiency of oxidation, are effective because they aid the conversion of carbon to CO and COz.…”

Section: Polyurethanesmentioning

confidence: 99%

The behaviour of thermoset polymers under fire conditions

Nicholson

Nolan

1983

Fire and Materials

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This paper reviews the current literature on the behaviour of thermoset polymers under fire conditions. These polymers are important and widely used materials. They are generally infusible and insoluble, and consist, on the molecular scale, of extensive cross-linked networks rather than discrete macromolecules. Materials in this class include phenol-formaldehydes, epoxies, cross-linked polyesters, amino resins and polyurethanes. As the use of plastics generally has grown, so there have been changes in the conditions prevailing in modern fires, and such changes are described, together with the potential fire hazards arising from the varying uses of the individual thermosets. Subsequently, literature on the pyrolytic and combustion characteristics of these materials is reviewed in order to assess their probable behaviour in real fires. Finally, existing approaches towards improving their fire behaviour are described.

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Section: Polyurethanesmentioning

confidence: 99%

The behaviour of thermoset polymers under fire conditions

Nicholson

Nolan

1983

Fire and Materials

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“…From the synthetic point of view, silicone cyclic and linear oligomers are typically obtained from the hydrolysis of chlorosilanes , or hydrolysis of alkoxysilanes . These oligomers can be converted into higher molecular weight silicones (a) by equilibration with cyclic oligomers in the absence of a solvent, (b) using catalysts to polymerize oligomeric silanols either via condensation (using phosphoronitrile halides or bases such as n -hexylamine) or via condensation and cleavage (using strong acids or bases), and (c) via ring-opening polymerization of cylic oligomers, either in its anionic or cationic form. These polymers range from fluids to very viscous liquids and are usually cross-linked to obtain resins, coatings, and elastomers.…”

Section: Introductionmentioning

confidence: 99%

Disassembly of Elastomers: Poly(olefin sulfone)−Silicones with Switchable Mechanical Properties

Lobez

Swager

2010

Macromolecules

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An elastomeric polymer composite that can be disassembled at will into its individual components when exposed to mild bases is presented. The composite is formed of a poly(olefin sulfone) and a silicone bound together using "click" chemistry. The mechanical properties of the composites can be varied depending on their formulation. Its base-triggered decomposition is advantageous from the point of view of composite recycling and controlled release of chemicals.

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“…Thus, the effectiveness of the phosphorus can be greatly increased by the incorporation of a halogen.2,6J0 Unfortunately, halogens were found to deactivate the amine catalysts commonly used in the technology of rigid PU foams.1° Polyols containing halogens bromine or chlorine also offer a suitable means of flameproofing the PU foams. 6,10 The presence of cyclic structures in polymers is known to improve their fire performance and increase the char formation tendency during the combustion of these polymers.6,sJ0J6 An example of such a modification is provided by foams containing thermally stable groups, such as isocyanurates, carbodiimides, imides, formed as a result of respective reactions of polyis~cyanates. '~J~ These foams, however, were found to have some obvious shortcomings, such as a considerable friability, complicated production technology, and relatively higher prices, in comparison with conventional polyurethane f0ams.~OJ8Jg In recent years, polyols containing cyclic structure^^^^^^^^^^ have assumed growing importance in the technology of fire-retardant rigid PU foams.…”

Section: Introductionmentioning

confidence: 99%

Flammability and thermal properties of rigid polyurethane foams with additionally introduced cyclic structures

Żabski

Walczyk

Weleda

1980

J. Appl. Polym. Sci.

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SynopsisFlammability, smoke evolution, thermal, and thermomechanical properties of low-density rigid polyurethane foams obtained from different aromatic polyols were investigated. The foams were prepared according to a standard formulation ensuring the same foam phosphorus content. Cellular polyurethanes with the best fire resistance were obtained from polyols containing disubstituted naphthalene and biphenyl rings. A linear equation was proposed to describe the influence of various structural units of the polyurethane (the content of cyclic structures C,, nitrogen content CN, and crosslinking equivalent M,) upon its flammability, expressed in terms of its oxygen index (01) Thermal stability of crosslinked polyurethanes was not found to influence significantly their thermomechanical properties, while crosslink density and the type and quantity of cyclic structures additionally introduced did have a pronounced effect upon these properties. INTRODUCTIONCellular polyurethanes (PU) in the form of low-density rigid polyurethane foams are particularly inflammable because of their highly developed surface.1,2 Owing to their unusually low thermal conductivity and high strength-to-weight ratio, rigid P U foams are increasingly used as thermal insulation material^.^,^ Rigid PU foams have been used extensively in the construction field, and the potential for future growth in this market is considered to be great.5 Applications have increased because of needs to reduce construction costs and provide more effective thermal insulation materials for air-conditioned and electrically heated buildings. The oil embargo imposed by the OPEC nations has prompted various governments to propose far-reaching energy conservation programs. Rigid PU foams have been given an important and significant role in these programs.Rigid P U foams may cause serious hazard in some applications, e.g., if they do not possess a sufficient degree of fire resistance. In the last decade, a large number of articles dealing with the impkovement of the fire performance of polyurethane foams were published.6-10 Many new fire-retardant compounds and methods of their application were developed in order to obtain rigid PU foams with a maximum fire resistance. The emphasis of research efforts has shifted to flame-resistant composition of PU foams which are integral parts of the polyurethane chemical structure.8,10 Rigid PU foams prepared with reactive-type flame retardants comprise roughly 75% of total sales of flame-retardant The char acts as a mechanical barrier, so that the physical compactness of the material is preserved by preventing the access of oxygen to the material. Thus, the char a t least partially eliminates the exothermic oxidation reactions. The char also makes more difficult the evolution of gaseous and often toxic combustion products.2J1Phosphorus compounds that fulfil all the above-mentioned requirements are regarded to be the best flame retardants.2,6,12 The introduction of phosphorus into the rigid PU foams, however, results in a considerable d...

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Relationship Between Chemical Structure and Flammability Resistance of Polyurethanes

Cited by 8 publications

References 25 publications

The behaviour of thermoset polymers under fire conditions

The behaviour of thermoset polymers under fire conditions

Disassembly of Elastomers: Poly(olefin sulfone)−Silicones with Switchable Mechanical Properties

Flammability and thermal properties of rigid polyurethane foams with additionally introduced cyclic structures

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