ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
A study was made of rates and activation energies of thermal degradation of polymeta-methylstyrene, poly-alpha-deuterostyrene, poly-alpha-methylstyrene, and hydrogenated polystyrene, in the styrene type of polymers; and of two methyl methacrylates and one methyl acrylate, in the acrylate type of polymers. This study was carried out in the temperature range 240-355°C., by measuring rates of loss of weight of the samples, due to volatilization, by means of a very sensitive tungsten spring balance enclosed in a vacuum. The samples were limited to 5-6 mg. to avoid spattering. The activation energies were obtained by plotting the logarithms of the initial rates, against the inverse of absolute temperature. The styrene polymers, except hydrogenated polystyrene, degrade thermally chiefly into monomeric type molecules. The activation energy of these polymers is about the same as for polystyrene, which is 58 kcal. In the case of hydrogenated polystyrene, breaks in the chain occur at random, the same as in polyethylene. The activation energy is 52 kcal. Polymethyl methacrylate, like the styrene polymers, breaks mostly at the radical chain ends, yielding the monomer. The activation energy is 33 kcal. for a benzoyl peroxide polymerized, 150,000 MW polymer and 55 kcal. for a thermally polymerized, 5,100,000 MW polymer. Polymethyl acrylate follows a mechanism of random breaking of the chains, and the activation energy is 37 kcal.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1953.120110511
Permalink