Simulation of the glass transition and physical ageing

A kinetic model simulating the glass transition and enthalpic relaxation in poly(3-hydroxybutyrate) is introduced. The model is based on the concept that enthalpic relaxation or physical ageing is a continuation of the glass forming process and uses the KWW function to describe the glass formation process and the subsequent ageing of the glass. Non-linearity is introduced by incorporating a dependence of the relaxation time on the fictive temperature. The effects of non-linearity on the distribution of relaxation times and the physical ageing process are investigated together with the development of the endothermic ageing peak at the glass transition with increasing extents of ageing.