Relation between the development of structure and the properties of network polymers

It was shown by various techniques that the development of structure in the early stages of cure determines the final structure and properties of glassy three-dimensional networks. Solid state [13C]-nuclear magnetic resonance (NMR) techniques identified the structure groupings and the extent of heterogeneity soon after the commencement of polymerization through to the glassy state. Observations of the changes in mobility of groups during cure were correlated with the development of bulk properties such as the glass transition and compressive strength. Computer simulation of the kinetics of the polymerization based on a three-dimensional lattice closely followed the trends observed by experiment and provided insight into the formation of clusters of reacted polymer surrounded by pools of unreacted monomer. The difficulty in obtaining full cure was clearly associated with the presence of trapped reactive centres within the cluster. Observation of the behaviour of small probe or tracer molecules by NMR was shown to be a potent technique for investigating the organization of networks. 28 refs., 12 figs