On-line Monitoring of Epoxy Resin Cure using Infrared Spectroscopy

Abstract

The method described can be used to observe the cure in epoxy resins, it is a sensor to serve as an on line monitoring system of physical change of the resins during the curing time and the future behaviour of the part built. It is also proposed that the method can be applied in Stereolithography (SL). In this paper the method permits a rapid determination of the state of chemical reaction happening in an epoxy resin diglycidyl ether of bisphenol A (DGEBA) with a curing agent triethylenetetramine stoichiometric mixture. It uses a mid infrared Fourier transform (FT-IR) technique to analyse the mixture via an embedded fibre optic and an FT-IR spectrometer operating in the region of 4000-700 cm-1. An accurate concentration versus time of epoxy amine and the hydroxyl groups gave a good estimate of the extent of reaction. The chemical group peaks at 1132cm-1 and 3300-3400cm-1 where used to follow the disappearance of the epoxy, and the amine respectively, while the peak at 2970cm-1 was used as reference peak. A review of a number of techniques used in the study of the curing process of epoxy resins and a number of methods used in an on-line monitoring of thermoset resin cure process is referred to Keywords: Streolithography, epoxy/amine cure, FT-IR spectroscopy, extent of reaction, fiber optic sensor.Mechanical Engineerin

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