Advanced Cure Monitoring and Analysis for Optimization of Thermoset Resin Processes
Being able to monitor the kinetic behavior of thermosetting materials will aid in the optimization of processing conditions and in understanding the final material properties obtained within a part. The properties of thermosets are a function of the degree of conversion, which itself is a function of multiple material and process variables, making the curing reaction an essential stage to control during processing.
Cure monitoring methods developed for the optimization of thermoset processes and final mechanical properties were studied. A new method consisting of the use of a dispersive Raman system with non-contact optics has been developed. The equipment built for the application consists of a pressure reactor in which the heating rate of a small sample is controlled with a control system that reacts to direct changes in sample temperature. Simultaneously, reaction is monitored by emitting a Raman laser into the chamber. The reaction progress of accelerated unsaturated polyester pultrusion grade resin and coating grade epoxy resin was monitored with the developed system. When running unsaturated polyester DSC samples uncontrollable overheating was obtained. In contrast, when the same material was tested with the designed chamber, overheating effects were minimized or eliminated.
Effects of pressure on reaction rates and final mechanical properties were studied. For accelerated unsaturated polyester reactions, increasing pressure resulted in a competing effect on the reaction rate. The final mechanical properties exhibited a similar behavior. For epoxy, reaction kinetics were accelerated by pressure, although no final mechanical property differences were determined.
Furthermore, using cure monitoring and optimization techniques, a special wood impregnation application has been developed. In this application, precise control of the curing behavior is essential for the process to work successfully. A linseed based epoxy resin was the material selected for the process. This new resin has never been evaluated for impregnation applications. It was found that synergistic effects between the wood and the resin lead to far superior properties as a composite than as individual materials. Substantial hardness and modulus increases were obtained for impregnated parts. Although more research has to be completed for the application, using cure monitoring and optimization techniques, made impregnation of wood with linseed epoxy resin a viable technique to greatly improve properties of softwoods to the level of expensive hardwoods.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
Curing Kinetios, thermosets, Raman–Spektroskopy, DSC
Institute / chair: University of Wisconsin at Madison
Technical consultant for expert services: Prof. Dr. Tim A. Osswald
Publication year: 2008
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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