Concurrent Decomposition Research Articles

Kinetics of neopentyl chloride pyrolysis. II. The radical-chain decomposition

The radical-chain thermal decomposition of neopentyl chloride was studied in the temperature range of 410–496 °C and over the pressure range of 22 to 340 mm. A small surface effect was noted after prolonged conditioning of the vessel and in a vessel of high surface/volume ratio. The reaction is of three-halves order and the rate coefficient is expressible by k3/2 (11/2 mole−1/2 s−1) = 1013.55 ± 0.67 × e−56300 ± 2100/RT. The experimental facts are shown to be consistent with a mechanism involving chlorine atoms as the principal propagating radicals, with a first-order initiation step and a termination step involving the combination of methyl and chloromethyl radicals. The relative concentrations of the various radicals, calculated from known and estimated kinetic parameters, have been shown to be dependent on the hydrogen chloride produced from the concurrent unimolecular decomposition of neopentyl chloride reported in Part I. 1,1-Dimethylcyclopropane, found as a reaction product, is believed to be formed directly from neopentyl chloride by a radical-chain mechanism.

Radiation crosslinking of vinyl chloride–vinyl stearate copolymer

AbstractThe crosslinking of internally plasticized polyvinyl chloride–stearate copolymer by irradiation with high‐energy electrons was studied. Based on gel yields and swelling as a measure of relative crosslinking, the effect of added tetra‐functional monomers, and of carbon black and silica fillers are discussed. Crosslinking by dicumyl peroxide a t 170°C. even in the presence of a stabilizer, causes concurrent decomposition (dehydrochlorination) which is avoided in the radiation‐crosslinking process. The heat stability of the copolymer is not impaired by radiation crosslinking under the proper conditions. Results of tensile measurements a t 25 and 150°C. are given for the radiation‐crosslinked copolymer with and without filler reinforcement.