Influence of Cross-Linking Density on the Glass Transition and Structure of Chemically Cross-Linked PVA: A Molecular Dynamics Study

Mechanical properties and glass transitions of cross-linked polymer networks depend strongly on both the network topology and cross-linking density. A model is developed using a dynamic cross-linking approach based on a cutoff distance criterion followed by a high-temperature annealing procedure. The analysis focused on on the influence of cross-linking degree on chain packing and hydrogen-bond structure and on the roles played by various energy components in the glass transition process. T-g was calculated using two different methods; (i) from the intersection of lines drawn through points in a plot of specific volume versus temperature and (ii) from plots of different molecular energy components as a function of temperature.