Chemical and diffusion control in isothermal curing kinetics

摘要

During an isothermal polymerization reaction a thermosetting resin vitrifies if thernreaction temperature is lower than the maximum glass transition temperature of the fully reactedrnmaterial. Due to the vitrification process the kinetics become diffusion-controlled. The kineticsrnof such reactions can be described by a product of a diffusion control function and the reactionrnrate of the chemically controlled reaction.rnIt is shown that the chemically controlled kinetics can be evaluated using isoconversionalrnmethods (model-free kinetics) from DSC heating experiments at sufficiently high heating rates.rnFor the diffusion control function a new phenomenological expression is introduced, which isrnindependent from the reaction temperature and requires only one parameter. This parameter canrnbe interpreted as the width of the glass transition.rnBased on a small number of experiments the presented approach can be used to predictrnthe kinetics of complex reactions, including chemical and transport processes.