This article presents the results of an investigation of the Raman scattering effects of aging
Kevlar strands. The goal of this research was to investigate the potential application of
Raman spectroscopy as a nondestructive evaluation tool for the detection of aging effects
of in-service composite materials. Kevlar composites used as overwrapping of metal-lined
composite overwrapped pressure vessels (COPVs) have been analyzed. Raman spectra
produced from the Kevlar fibers and the effects of resin materials, utilized to bind the fibers
into strands to provide composite behavior, have been investigated. A series of Kevlar=
epoxy strands exposed to elevated temperatures and sustained loading have been
evaluated. It was found that this exposure had an effect on the width and intensity of
certain bands in the Raman spectra of Kevlar. The potential application of these findings
1. L. S. Schadler and C. Galiotis. International Materials Reviews 40(3):116–133 (1995).
2. J. R. Ferraro and K.Nakamoto. Introductory Raman Spectroscopy, Academic Press, Inc., San Diego (1994).
3. J. L. Koenig. Spectroscopy of Polymers, ACS, Washington, DC, Professional Reference Book (1992).
4. L. Penn and F. Milanovich. Polymer 20(1):31–36 (1979).
5. P. K. Kim, C. Chang, and S. L. Hsu. Polymer 27(1):34–46 (1986).
6. C. Chang and S. L. Hsu. An analysis of strain-induced frequency changes in poly (p-phenylene
terephthalamide) single fibers. Macromolecules 23:1484–1486 (1990).
7. M. C. Andrews, D. J. Bannister, and R. J. Young. The interfacial properties of aramid=epoxy model
composites. Journal of Materials Science 31:3893–3913 (1996).
8. C. Galiotis, I. M. Robinson, R. J. Young, B. Smith, and D. N. Batchelder. Strain dependence of the
raman frequencies of a kevlar 49 fiber. Polymer Communications 26:354–355 (1985).
9. M. Kawagoe, S. Hashimoto, M. Nomiya, M. Morita, J. Qiu, W. Mizuno, and H. Kitano. Effect of water
absorption and desorption on the inerfacial degradation in a model composite of an aramid fiber
and unsaturated polyester evaluated by raman and FT infra-red microscopy. Journal of Raman
Spectroscopy 30:913–918, (1999).
10. K. Prasad and D. T. Grubb. Deformation behavior of kevlar fibers studied by raman spectroscopy.
Journal of Applied Polymer Science 41:2189–2198 (1990).
11. B. H. Stuart. A fourier transform raman study of water sorption by kevlar-49. Polymer Bulletin 35:
12. F. P. Gerstle. Prediction of Long-term Failure in Kevlar 49 Composites. in SAND-81-2072C;
CONF-820340-2. Sandia National Laboratories – Albuquerque, NM (1982).
13. M. I. Zeifman and D. Ingman. Statistical aspects of lifetime in the presence of UV radiation. Journal of
Electronic Packaging 125(1):1–3 (2003).
14. S. Mahesh and S. L. Phoenix. Lifetime distributions for unidirectional fibrous composites under
creep-rupture loading. International Journal of Fracture 127:303–360 (2004).
15. H. Otani, S. L. Phoenix, and P. Petrina. Matrix effects on lifetime statistics for carbon-epoxy
microcomposites in creep rupture. Journal of Materials Science 26:1955–1970 (1991).
16. N. Ativitavas, T. Fowler, and T. Pothisiri. Identification of fiber breakage in fiber reinforced plastic by low
amplitude filterian of acoustic emission data. Journal of Nondestructive Evaluation 23(1):21–36 (2004).
17. G. Washer and S. Allempalli. NDE Technologies for Condition Assessment of FRP Retrofits. In ASNT
Fall Conference, (2005). Columbus, OH.
18. V. M. Karbhari, J. W. Chin, D. Hunston, B. Benmokrane, T. Justka, R. Morgan, J. J. Lesko, U. Sorathia,
and D. Reynaud. Durability gap analysis for fiber-reinforced polymer composites in civil infrastructure.
Journal of Composites for Construction 73:238–247, (2003).
19. K. G. N. C. Alwis and C. J. Burgoyne. Stepped Isothermal Method for Creep Rupture Studies of Aramid
Fibers. In ACI Special Publications, (2005).
20. V. M. Hallmark. ed. FT – Raman Spectroscopy as a Structural Probe of Polymers and Other Long-
Chain Organic Molecules. In Fourier Transform Raman Spectroscopy, D. B. Chase and J. F. Rabolt
(ed.), (1994). Academic Press, Inc., San Diego.
21. J. Parthenios, D. G. Katerelos, G. C. Psarras, and C. Galiotis. Aramid fibers; a multifunctional sensor
for monitoring stress=strain fields and damage development in composite materials. Engineering
Fracture Mechanics 69:1067–1087 (2002).
22. R. J. Young, R. J. Day, and D. Lu. Raman spectroscopy of kevlar fibers during deformation – caveat
emptor. Polymer International 24:71–76 (1991