Non-isothermal degradation kinetics of Un-irradiated and High Energy Protons Irradiated Polyvinyl Butyral

One of the methods of modification, upgrading, stabilization and changing the properties of polymers is based on the irradiation with high energy accelerated radiation (gamma rays, X-rays, and accelerated ion beams). Irradiation of polymers with high energy radiations leads to the formation of very reactive intermediates in the forms of excited states, ions and free radicals. These intermediates are almost instantaneously used up in several reaction pathways which result in the arrangement or formation of new bonds structures. The ultimate effects of these reactions are the formations of oxidized products, grafts, cross-linking and scissoring of main or side chains which are also called degradation. The degree or dominance of these transformations depend on the nature of the polymer and the conditions of treatment before;, during and after irradiation and close control of these factors make the modification of polymers possible by radiation processing.In this study the thermal behavior and Kinetic models for decomposition of the irradiated and unirradiated polyvinyl butyral (PVB) were investigated based on DTA and DTG thermograms, as well. Experimentally, solid-state kinetics is studied either isothermally or nonisothermally. Many mathematical methods have been developed to interpret experimental data for both heating protocols. These methods generally fall into one of two categories: model-fitting and model-free. Historically, model-fitting methods were widely used because of their ability to directly determine the kinetic triplet (frequency factor [A], activation energy [Ea] and model). There are many model fitting methods that extract the three kinetic parameters known as the kinetic triplet from nonisothermal data. These methods were used extensively earlier in solid-state kinetic analysis [۱-۷]. In the present work, we used nonisothermal model-fitting direct differential method.

Keywords:

Thermal decomposition , Proton irradiation , polyvinyl butyral