Poly fire mechanism

Aryloxyphosphazene copolymers can also confer fireproof properties to flammable materials when blended. Dieck [591] have used the copolymers III, and IV containing small amounts of reactive unsaturated groups to prepare blends with compatible organic polymers crosslinkable by the same mechanism which crosslinks the polyphosphazene, e.g. ethylene-propylene and butadiene-acrylonitrile copolymers, poly(vinyl chloride), unsaturated urethane rubber. These blends were used to prepare foams exhibiting excellent fire retardance and producing low smoke levels or no smoke when heated in an open flame. Oxygen index values of 27-56 were obtained. 

Liquid chlorinated paraffins are the main halogen-containing fire-retardant additives used for poly(vinyl chloride) often in combination with a phosphate ester. In this case, the chlorinated paraffins have the secondary function of plasticizers. The thermal degradation mechanism of chlorinated paraffins is similar to that of poly(vinyl chloride), so in this case poly(vinyl chloride) stabilizers have also the secondary function to stabilize chlorinated paraffins. 

Manzi-Nshuti, C., Wang, D., Hossenlopp, J. M., and Wilkie, C. A. Aluminum-containing layered double hydroxides The thermal, mechanical, and fire properties of (nano)composites of poly(methyl methacrylate), J. Mater. Chem. (2008), 18, 3091-3102. 

In contrast to stabilizers, fire retardants must be added in much higher concentrations, which affect thermal and mechanical properties as well as cost. Sherr and co-workers report that novel derivatives of phosphine oxides, phosphonic acids, phosphinic acid, and phosphonium halides may be used generally in concentrations as low as 2.5-5 p.p.h. to be effective fire retardants in polyethylene and poly (methyl methacrylate). 

The polymerization is carried out in two stages—initially the aromatic poly-imide is obtained and in the latter stage, etheric bonds are introduced. The polymer is thermoplastic. PEI represents an unique engineering polymer exhibiting a superb combination of mechanical and thermal performance, easy processibility together with a reasonable price. It also withstands UV radiation, fire and many chemicals, but may be sensitive to alkalinity. Mainly reinforced, it serves as a substitute for metals in first class electronic and engineering appliances. 

The presence of phosphorus in the polymer backbone has a veiy practical consequence, quite apart from the structural issues. Phosphorus is one of the most important elements that prevent the combustion of organic materials. The presence of both phosphorus and nitrogen is synergistic. Thus, the phosphorus-nitrogen backbone in polyphosphazenes ensures that many poly(organophosphazenes) are not only nonflammable but also quench combustion of other compounds with which they are in contact. The mechanism of this fire suppression is believed to be both an interruption of the free radical processes that occur in a flame and the formation of an intumescent char that shields the material from the ingress of oxygen. 

Superconducting ceramics of Y,Ba2Cu30jj g have been used as substrates for the electrochemical deposition of either poly pyrrole or poly thiophene [87]. Ceramics are typically obtained by firing pressed powders of the oxide compounds. Thus, electrical and mechanical contacts made between the ceramics and wires produced mechanically or by vacuum deposition of metal are often found to be inadequate. Superconductors modified by conducting polymers may help improve the contact area. 

As a result of their outstanding physical and mechanical properties, aromatic polyamides are attractive materials for use in high-performance structural applications 853072 833611 820253, including aircraft components or fire protection garments, as constituents of both traditional, i.e., fibre-reinforced composites 774110 762844, and molecular composites. One of these applications takes advantage of their thermal stability 881232 825031 763791 755849 and allows the manufacturing of heat-resistant materials for fire protection 713906. In a different context, aromatic polyamides (aramid fibres) have been proposed in the past few years as precursors of activated carbon materials with distinctive adsorbent properties (thermally stable molecular sieves). Aramid fibres, e.g., poly(w-phenylene isophthalamide), poly(p-phenylene terephthalamide) 709654, etc., are a class of synthetic polymers that possess excellent thermal and oxidative stability, good flame resistance, and superior mechanical and dielectric behaviour. 

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