Fiber optic flow and cure sensing for liquid composite molding

The Polymer Composites group at the National Institute of Standards and Tec hnology has efforts in both on-line flow and cure sensing for liquid compos ite molding. For our flow program, a novel fiber optic real-time sensor sys tem has been developed that can sense resin at various locations on a singl e fiber using long-period gratings and a polychromatic source. The sensor o peration and characterization will be discussed along with sensor performan ce during mold filling with various types of reinforcement. The cure sensin g program focuses on the interface-sensitive fluorescence response of a dye molecule grafted to a high-index glass fiber. The fluorescence emission of the fluorophore undergoes a blue shift as the resin cures. The fluorescenc e sensor is made by grafting a silane functional fluorophore onto the surfa ce of the glass with close attention to layer thickness. Fluorescence emiss ion of the grafted fluorophore film is shown to be sensitive to epoxy resin cure, co-silane, and layer thickness. The response of the grafted fluoroph ore to cure on a high-index fiber is demonstrated. Published by Elsevier Sc ience Ltd.