Physical ageing of amorphous polymers. Theoretical analysis and experiments on poly(methyl methacrylate)

摘要: Structural relaxation of glassy poly(methyl methacrylate) (PMMA) was studied with several techniques: differential scanning calorimetry (DSC), volumetry by thermomechanical analysis (TMA) and mechanical spectroscopy. A theory is proposed in order to interpret the data a unique theoretical framework. This developed on basis two main physical assumptions: (i) existence amorphous polymers quasipunctual defects whose concentration decreases during structural relaxation, (ii) occurrence hierarchical correlation effects conditioning molecular mobility. As first approximation self-consistent semiquantitative description results obtained, i. e., experimental obtained for different quantities PMMA can be accounted employing always same set model parameters. However, it seems that significant difference exists between times associated techniques.