Some Modern Aspects of Elastomer Science and Technology

University Of Cincinnati Main Campus, Cincinnati OH

Investigators

Abstract

One practical goal of the research proposed is to obtain structure-property relationships that can be used to optimize the properties of elastomeric materials. For example, stress-strain results on a variety of elastomeric materials in elongation, biaxial extension, shear, and torsion will be interpreted using both analytical theories based on entanglement-constrained network junctions, and computer simulations. Elastomers will include both commercially important polymers cross linked by some of the relatively uncontrolled techniques used in the industry, but also some elastomers prepared to have unusual bimodal chain-length distributions that improve ultimate properties by end linking functionally-terminated polymer chains. Additional elastomers will be produced under conditions giving structures that have some unusual advantages, for example by cross linking in solution or in a state of strain. Experiments on these materials that are of particular interest will be stress-strain measurements for identifying maximum extensibilities and toughness. Elastomeric gels will be used to produce biodegradable films of enhanced orientation and improved mechanical properties. The second major topic involves strain-induced crystallization in elastomers, in elongation, but also in several important deformations in which results are almost entirely lacking. Some analytical theory and computer simulations will be carried out in parallel investigations. Novel reinforcing fillers such as silica will be generated in-situ by hydrolyses of precursors such as organosilicates, and simple metal salts such as ferric chloride. Of particular importance will be identifying the particle size that maximizes reinforcement, and characterizing the effects of particle shape and the orientations of non-spherical particles. Novel materials will be prepared by coating particles of one type with a ceramic of another type. It will also be possible to thread elastomeric chains through reinforcing zeolites. The resulting filler-reinforced elastomers will be characterized primarily by mechanical property measurements, electron microscopy, X-ray and neutron scattering, and pulse-propagation measurements. Simulations will also be carried out to elucidate reinforcing mechanisms in filled elastomers in general. As a final topic, experiments will be carried out to exploit the ability of elastomeric domains to improve the impact resistances of polymer-ceramic hybrid composites in which the ceramic is the continuous phase. Of particular interest here is control of the level of dispersion by using the connectivity of networks structures in one of the phases to "frustrate" the usual types of phase separation in disparate two-component systems. Broader impacts, described within the proposal, include developing a module on elastomers and rubberlike elasticity for deployment in a "Mobile Laboratory" to bring science and engineering demonstrations and experiments to K-12 students in Cincinnati. Three large "Winnebago" sized mobile classrooms are being outfitted, and each will be stocked with the equipment necessary to allow students the opportunity to carry out more advanced experiments than usually possible in typical K-12 venues.