Characterization of poly (vinyl chloride) prepared by radiation‐induced bulk poly‐merization at temperatures from −50° TO 90°C

Abstract

Osmotic, viscometric, and light scattering measurements have been carried out on poly (vinyl chloride) samples, obtained by bulk polymerization on exposure to 60Co γ‐rays at dose rates varying over a 100‐fold range and at regularly spaced temperatures from −50 to 90°C. While with the samples prepared at the higher temperatures, solutions could be conveniently made in tetrahydrofuran, cyclohexanone appeared to be a more suitable solvent when polymerization temperatures from 10°C downwards were concerned. Furthermore, with the latter cases, strong heating treatments of the solutions were required. Correlations among the various parameters, deduced from the measurements, were examined and found in agreement with reported relationships for conventional poly (vinyl chloride). The patterns of gradual change of molecular weight with changing polymerization conditions were discussed.

Single-Electron Transfer and Single-Electron Transfer Degenerative Chain Transfer Living Radical Polymerization

“…The only method available for the production of PVC is free-radical polymerization in suspension, emulsion, and bulk. In the absence of additives, PVC is brittle, has a broad molecular weight distribution, contains relatively few intact chain ends, and possesses tertiary chloride and allyl chloride structural defects − that lead to zipperlike dehydrochlorination reactions when the temperature is elevated above T g . To combat these deficiencies, PVC is stabilized with organometallic compounds that are added to inhibit decomposition.…”

DFT Calculations Suggest a New Type of Self‐Protection and Self‐Inhibition Mechanism in the Mammalian Heme Enzyme Myeloperoxidase: Nucleophilic Addition of a Functional Water rather than One‐Electron Reduction

“…Such a process is largely accompanied by side reactions that lead to the formation of structural defects, such as tertiary and allylic chlorine groups 16–20, 26, 27, 31. These defects are responsible for the low thermal stability of PVC because they initiate a zipper mechanism of thermal dehydrochlorination and therefore lead to the most relevant technological limitations of PVC 16–35. At temperatures higher than 60 °C, conventional radical polymerization of VC is dominated by chain transfer to monomer ( C m ) rather than bimolecular termination 35, 36–39.…”