Wednesday, February 5, 2014

Flammability of Polymers

Assignment B Flammability of polymers Combustion and Decomposition of polymers Most polymers atomic number 18 made up of small hydrocarbons recurrent to form a vast chain molecule. In wake up generally the passe-partout polymer remains mostly in inconstant. The cock-a-hoop polymer molecules decompose via pyrolysis (Thermochemical decomposition without oxygen) creating passing reactive free radicals which in turn help rifle down more of the long chain. In the heat the molecules perpetually decompose in the condensed microscope stage ( solidity or liquid) into smaller scummy molecular weight, highly vapourisable molecules. These small molecules vaporize and gravel fire easily if the temperature rises in a higher place fervor temperature. Decomposition shorten out run as long as the temperature is abundant to continue thermal decomposition and in turn yield the chars with volatile compounds. An example of the decomposition of a polymer (polyethene) to sma ller molecules is shown infra (derived from plat examples on Sciencedirect.com and Uclan.ac.uk): Initiation - polymer chain [pic] + HEAT telephone extension (many possible combinations) [pic] + [pic] [pic] + CH2=CH2 [pic]+ [pic] Termination- (Gas phase) Volatile species organize (again many possible forms) CH2=CH2 CH2=CH-CH3 CH3-CH3 [pic] These smaller molecules essentially fuel the polymer to shorten more once ignited. The flame heats the polymer causing it to decompose further, relinquish more fuel for the flames. This creates a self sustaining hit the ceiling cycle. When the flames burn longer and lower hotter larger molecules will r distributively their ignition temperature and burn creating a fiercer fire. COMBUSTION CYCLE DIAGRAM The diagram above shows the electrocution cycle of a polymer. The pha se boundary shows what narrate each part ha! ppens. The pyrolysis of the polymer happens in the condensed phase as a solid or a liquid. This is the state in which the heat...If you lack to get a full essay, order it on our website: OrderCustomPaper.com

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