CURE MONITORING OF ADVANCED FIBRE REINFORCED COMPOSITES USING AN OPTICAL FIBRE SENSOR

摘要

An optical fibre monitoring technique based on transmission near-infrared spectroscopy was applied to follow the cure reactions of two epoxy resin systems: (ⅰ) a model system consisting of a diglycidyl ether of bisphenol-A (DGEBA) epoxy resin cured with 1,6 hexanediamine; and (ⅱ) a commercial epoxy resin system, Fibredux 924, a resin used extensively as the matrix for advanced fibre reinforced composites. The sensor allowed the actual concentration of epoxy groups to be tracked during cure thus providing valuable information for processing. The sensor design was based on two cleaved optical fibres aligned with a small gap (～750μm) between their end-faces. Light scanned from 2100-2250 nm was launched into one of the optical fibres, across the transmission gap before being received by the second fibre connected to a detector. For cure monitoring, the sensor was embedded in the resin before processing. As the sample was heated up during the cure cycle, the viscosity of the resin was such that it flowed into the gap between the optical fibre-ends. This allowed the near-infrared spectrum of the resin to be collected during processing and consequently the concentration of epoxy groups to be calculated from the characteristic epoxy absorption peak at 2212 nm.