TOPOLOGICALLY INTERPENETRATING POLYMERIC NETWORKS (POLYURETHANES, EPOXIES, ACRYLICS).

摘要

This study was concerned with the synthesis and characterization of topologically compatible three-component interpenetrating polymer networks (IPN's). IPN's synthesized during the course of this research work were prepared from polyurethanes, epoxies, and poly (methacrylates). Prior studies on IPN's involved two-component systems which exhibited heterophase morphologies and varying degrees of phase separation. The inroduction of a third component network made it necessary to alter synthetic variables within the systems to give the best compatibility among the polymers, and hence obtain optimum physical and mechanical properties. One of the principal methods for achieving this goal was the introduction of functional groups into one or more of the constituent polymers. Factors affecting the kinetics of polymerization and cross-linking, such as temperature, catalyst, and catalyst concentration, were manipulated in order to control the relative rates of reaction and allow for the highest possible degree of interpenetration among the networks. Similar types of chemical structures were incorporated into the respective polymer backbones in order to improve the phase mixing among the polymers. Changes in system functionality and composition ratios were made to enhance a permanent and maximum interpenetration of the networks in the IPN's. Comparisons of properties and morphologies were made for linear polyblends, pseudo IPN's, full IPN's, graft IPN's, and grafts of two- and three-component IPN systems. The physical and mechanical properties, as determined from stress and strain measurements, were generally improved for full IPN's and grafts over the other types of polymer alloys. All of the IPN's exhibited synergystic behavior and better properties than the parent homopolymers. IPN's prepared from polymers containing opposite-type functional groups showed enhanced phase mixing in comparison to the similar-type functional group IPN's and the functionally-free IPN's. Most of the three-component IPN's synthesized in this study exhibited single glass transition temperatures as measured by dynamic viscoelastometry, thermomechanical analysis and differential scanning calorimetry. A variety of new and useful IPN materials were formed ranging from rubber-toughened adhesives to reinforced elastomers and coatings.