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
