Idriss Blakey - Modeling of infectious spreading in heterogeneous polymer oxidation II. Refinement of stochastic model and calibration using chemiluminescence of polypropylene.

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      Publication Details (including relevant citation   information):

      Goss, B. G. S.; Blakey, I.; Barry, M. D.; George, G. A., Polymer   Degradation and Stability 2001, 74 (3), 523-532.


      In the stochastic model for infectious spreading of oxidation in   a  polymer, the conventional view of a homogeneously   oxidising polymer with  associated rate parameters is   replaced by a system consisting of  localized zones of   oxidation in a continuous unoxidised substrate (a    3-dimensional matrix) with the rate of degradation controlled by   the  probability of passing the infection to an adjacent   site, and the  infectious lifetime of the site. The   populations in the epidemiological  model for spreading of   oxidation, pi (the infectious, oxidising   fraction), pr (the remaining, unoxidised   fraction) and pd (the dead or oxidised   fraction) are calculated for a particular site.    Oxidation-time profiles are determined by calculating the sum of   the  component fractions over the entire matrix volume for   different  activities (i.e. temperatures). Profiles of the   infectious fraction, pi,  at different   activities were found to show features of an accumulating    hydroperoxide fraction whereas the true infectious fraction   should be  more correctly represented by the   reactive fraction of the hydroperoxides,   pi*,  at a particular   temperature. This model has been tested by comparison  with   the reactive hydroperoxide profile as determined by    chemiluminescence of polypropylene doped with 9,10-diphenyl   anthracene  to yield the infectious spreading parameters,   their temperature  dependence, as well as the profiles for   the diffusion of the infectious  species.

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