Sample records for chlorobutadiene

  1. Newly developed chloroprene rubber composites based on electron-modified polytetrafluoroethylene powder

    Energy Technology Data Exchange (ETDEWEB)

    Sohail Khan, M., E-mail: [Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden (Germany); Lehmann, D.; Heinrich, G. [Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden (Germany)


    Compatibility via chemical coupling between electron-modified polytetrafluoroethylene (PTFE) powder and poly-2-chlorobutadiene rubber is accomplished by activation of the radiation-induced carboxylic groups on the PTFE surface by zinc oxide. This is achieved both prior to and during reactive blending of zinc oxide with chloroprene rubber. Spectroscopic analysis of the reaction products reveals an increase in characteristic chloroprene absorption ({approx}1660 cm{sup -1}) due to the stretching of the C=C bond. Microscopic observations suggest that the PTFE dispersion is considerably improved, while the state of interphase between the PTFE particles and the chloroprene rubber indicates enhanced compatibility. The increase in the cross-link density determined by Mooney-Rivlin plots provides indirect evidence for the existence of chemical coupling. PTFE-based chloroprene composite exhibits a significant increase in modulus due to the strong reinforcement effect of the modified PTFE powder. Finally, we propose an explanation of the coupling mechanism based on the chemical activation of carboxylic groups in the PTFE powder in the presence of zinc oxide.

  2. Popcorn polymerisation of chloroprene. A kinetic investigation

    International Nuclear Information System (INIS)

    The project was sponsored by Du Font Dow Elastomers Ltd (Maydown, N. Ireland), in whose neoprene plant the popcorn polymers are found. The material itself has no commercial value, but grows rapidly and has the ability to block pipes and halt production. Therefore the production equipment containing monomers is all scheduled for 'popcorn search' inspections at intervals that differ according to the prevailing temperatures and monomer concentrations; a process which adds to costs. Prior work within the Queen's University of Belfast has identified the factors which affect the initiation of chlorobutadiene popcorn polymers, but available published and unpublished kinetic studies are in conflict concerning their rate of growth, and there is no data on the dichlorobutadiene popcorn polymer. In consequence, current relief system design procedures are based on a worst case scenario about popcorn growth rates and thus the design may be unduly expensive. The research obtained reliable kinetic data to allow these 'popcorn search' schedules to be rationalised and relief system designs to be improved and as a result to reduce the company's expenditure and improve operational safety margins. The proposed research was to investigate the kinetic behaviour of chlorinated butadiene monomers in the formation of omega- or 'popcorn' polymers. The growth rates of the chloroprene popcorn polymer were investigated at various temperatures in the liquid phase in the pure chloroprene monomer, mixed with other monomers and diluted with toluene in what we term 'Korean' type experiments. In these experiments the growth of popcorn polymer was terminated in a set of identically prepared ampoules after a fixed time. The growth rates of popcorn polymer seeds were obtained over various time periods, namely 24, 43 and 54 hours, at temperatures ranging from 10 deg C to 60 deg C. It was observed that the results differ greatly from those obtained by J.Op.Li. In particular, in the present work it was