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Monitoring of Curing Process of Epoxy Resin by Long-Period Fiber Gratings

Ivanov, Oleg V.; Bhavsar, Kaushal; Morgan-Clague, Oliver; Gilbert, James M.


Oleg V. Ivanov

Oliver Morgan-Clague


The curing of epoxy resin is a complex thermo-chemical process that is difficult to monitor using existing sensing systems. We monitored the curing process of an epoxy resin by using long-period fiber gratings. The refractive index of the epoxy resin increases during the curing process and can be measured to determine the degree of curing. We employed long-period fiber gratings that are sensitive to the refractive index of an external medium for the measurement of refractive index changes in the resin. We observed that the resonances of long-period fiber gratings increased their depth with the increased refractive index of the resin, which was well described by our simulation taking the coupling to radiation modes into account. We demonstrated that the degree of cure can be estimated from the depth of the grating resonances using a phenomenological model. At the same time, long-period fiber gratings are sensitive to temperature variations and internal strains that are induced during curing. These factors may affect the measurements of curing degree and should also be addressed.


Ivanov, O. V., Bhavsar, K., Morgan-Clague, O., & Gilbert, J. M. (2024). Monitoring of Curing Process of Epoxy Resin by Long-Period Fiber Gratings. Sensors, 24(11), Article 3397.

Journal Article Type Article
Acceptance Date May 22, 2024
Online Publication Date May 25, 2024
Publication Date Jun 1, 2024
Deposit Date Jun 13, 2024
Publicly Available Date Jun 14, 2024
Journal Sensors
Print ISSN 1424-8220
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 24
Issue 11
Article Number 3397
Keywords Long-period fiber grating; Epoxy resin; Resin curing; Refractive index sensor; Composite materials
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