Influence of conformational parameters on physical properties of polyimides containing methylene bridges

Conformational parameters, and free and Van der Waals volume values for a group of polymers containing methylene bridges, some of them having methyl substituents as well, have been calculated and correlated with physical properties such as solubility, glass transition and decomposition temperature, tensile stress and dielectric constant which were measured for these polymers. Thus, it was shown that conformational rigidity determines the packing of macromolecules in solid state, and therefore the free volume, and glass transition temperature and dielectric constant. The presence of methyl substituents and other flexible groups such as isopropylidene, carbonyl or hexafluoroisopropylidene has a more complex effect on the values of mechanical properties.