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A Fiber Optic Sensor for Composite Cure Monitoring



Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, J H. Van Zanten, Joy Dunkers, C G. Zimba, C A. James, S K. Pollack, Richard~undefined~undefined~undefined~undefined~undefined Parnas


The fiber/resin interface is critical to the final mechanical properties of a composite part. The extent f cure and cross-link density affect the resin structure in this interfacial region. In addition, the type of coupling agent coating the fiber, the structure of this coupling agent layer, and the interaction between the resin and coupling agent also affect the nature of this region. A probe, sensitive to these variables and covalently grated to a glass fiber optic, can give direct information about the nature of the fiber/resin interface. Robello (RBS), a silane coupling agent tethered with the dimethylaminonitrostilbene (DMANS) fluorophore, has been chemically grated to glass surfaces. We have shown that the fluorescence response of the grated RBS molecule is sensitive to many variables, including the dilution with other coupling agents, the chemical functionality of these coupling agents, and the thickness of the coupling agent layers. The wavelength maximum of the fluorescence response, λmax, changes as the solvent nature around the fluorescent probe changes. A shift in the wavelength maximum of the RBS can be followed as an epoxy resin cures, giving the grafted dye molecule potential as an interface sensitive cure monitoring sensor. When the covalently bound RBS is immersed in uncured epoxy resin, λmax approximately equal to} 600 nm. But the fluorescent response shifts to λmax approximately equal to} 580 nm in the cured epoxy. The extent of this fluorescence shift depends on the thickness of the coupling agent layer. Thin layers show the largest shift, due to the interaction between the RBS and epoxy resin. Thick layers show small shifts, due to extensive interaction between RBS and the surrounding coupling agent layer, as opposed to interaction with the resin itself.
Proceedings Title
Conference Dates
September 22-25, 1998
Conference Location
Conference Title
American Society for Composites. Technical Conference


composites, fiber optic, fluorescence, grafting, Robello siloxane


Lenhart, J. , Van Zanten, J. , Dunkers, J. , Zimba, C. , James, C. , Pollack, S. and Parnas, R. (1999), A Fiber Optic Sensor for Composite Cure Monitoring, Proceedings, Undefined (Accessed March 1, 2024)
Created February 28, 1999, Updated October 12, 2021