RAMAN SPECTROSCOPY AND CURE KINETICS STUDIES OF A DLS 772 AND 4 4’DDS EPOXY SYSTEM DURING THERMAL AND MICROWAVE CURING

Abstract

This research was carried out in order to further understand the effects of microwave heating on the functional groups and curing of epoxy systems. Raman Spectroscopy was used to record the stokes and the antistokes spectra of Diglydicydyl Ether of Bisphenol A (DGEBA) and 4,4’ Diphenyldiaminosulfone (DDS) epoxy system at different temperatures during conventional and microwave cure, and their molecular temperatures were calculated from the data obtained. The temperatures showed that thermal heating does not excite the functional groups of the epoxy resin and the hardener, as their molecular temperature was in the same region as the cure temperature whereas Raman spectroscopy was unable to produce any stokes or antistokes spectra during microwave curing of the epoxy system. The cure kinetics of the DLS 772 / 4, 4’ DDS system was also studied by using Differential Scanning Calorimetry (DSC) and a Microwave heated calorimeter. The DSC results showed that microwave curing of the DGEBA / 4, 4’ DDS system began at a higher temperature than thermal curing. Higher rates of reaction and activation energies were also observed in the microwave cured samples. The temperature at which fractional conversion began increased with increase in heating rate during microwave curing, but it was independent from heating rate during conventional cure. The rates of reaction also increased with an increase in heating rates for both thermal and microwave cure. These results suggest that, compared to conventional heating, microwave heating is more efficient curing technique which leads to more uniform cure and less internal stresses within the material.

Keywords

• Raman Spectroscopy,Epoxy,Microwave,Cure Kinetics

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