Assessment of Dielectrometry for Characterization of Processing and Moisture Absorption in FRP Composites

Abstract

The increasing use of ambient cured resin systems for the fabrication of composites used in structural components such as in civil infrastructure creates a need for monitoring cure progression over time as well as for tracking changes due to environmental exposure during the extended period of time needed to attain full cure. Further, there is a need for the development of methods to monitor the health of structures in the field for applications such as column retrofit, external strengthening of girders and slabs, and even bridge decks. This paper investigates the application of dielectrometry to the characterization of E-glass epoxy composites exposed to deionized water. Results are correlated with DSC and moisture absorption. It is shown that a direct correlation between moisture absorption and permittivity can be obtained.

References

1. Adamec, V. (1972). Electrical Properties of an Epoxy Resin During and After Curing , Journal of Polymer Science, Part A-1, 10: 1277–1295 .

2. Affrossman, S., Banks, W.M., Hayward, D. and Pethrick, R.A. (2000). Non-destructive Examination of Adhesively Bonded Structures Using Dielectric Techniques: Review and Some Results , In: Proceedings of the Institute of Mechanical Engineers, Part C, Vol. 214, pp. 87–102 .

3. Boinard, P., Pethrick, R.A. and Banks, W.M. (2000). High-Frequency Dielectric Spectroscopy as NDE Technique for Adhesively Bonded Composite Structures, In: Cardon, A.H., Fukuda, H., Reifsnider, K.L. and Verchery, G. (eds.), Recent Developments in Durability Analysis of Composite Systems, pp. 331–336. Balkema, Rotterdam .

4. Collings, T.A. (1986). The Effect of Observed Climatic Conditions on the Moisture Equilibrium Level of Fiber-Reinforced Plastics , Composites, 17: 33–41 .

5. Day, D.R. and Shepard, D.D. (1990). Cure Monitoring: A Comparison of Dielectric and Thermal Analysis , In: Proceedings of the 19th North American Thermal Analysis Conference, Boston, Vol. 2, pp. 523–529 .

6. Day, D.R., Shepard, D.D. and Craven, K.J. (1992). A Microdielectric Analysis of Moisture Diffusion in Thin Epoxy/Amine Films of Varying Cure State and Mix Ratio , Polymer Engineering and Science, 32(8): 524–528 .

7. Debye, P. (1929). Polar Molecules, Chemical Catalog Co., New York .

8. Enns, J.B. and Gillham, J.K. (1983). Time-temperature-transformation (TTT) Cure Diagram: Modeling the Cure Behavior of Thermosets , Journal of Applied Polymer Science, 28: 2567–2591 .

9. Halliday, S.T., Banks, W.M. and Pethrick, R.A. (1999). Dielectric Studies of Ageing in Aluminum Epoxy Adhesively Bonded Structures: Design Implication , In: Proceedings of the Institute of Mechanical Engineers, Park L, Vol. 213, pp. 103–119 .

10.

10. Karbhari, V.M. (2001). Materials Considerations in FRP Rehabilitation of Concrete Structures , ASCE Journal of Materials in Civil Engineering, 13(2): 90–97 .

11.

11. Karbhari, V.M. and Lee, R. (2002), On the Effect of E-Glass Fiber on the Cure Behavior of Vinglester Composites , Journal of Reinforced Plastics and Composites, 21(10): 901–918 .

12.

12. Karbhari, V.M. and Palmese, G.R. (1997). Sizing Related Kinetic and Flow Considerations in the Resin Infusion of Composites , Journal of Materials Science, 32: 5761–5774 .

13.

13. Kienle, R.H. and Race, H.H. (1934). The Electrical Chemical and Physical Properties of Alkyd Resins , Transactions of the Electrochemical Society, 65: 87 .

14.

14. Miklos, W.J., Sefaris, J.G., Appicella, A. and Nicolais, L. (1982) Evaluation of Structural Changes in Epoxy System by Moisture Sorption-Desorption and Dynamic Mechanical Studies , Polymer Composites, 3(3): 118–124 .

15.

15. Reid, D., Lawrence, W.H. and Buck, R.P. (1986). Dielectric Properties of an Epoxy Resin and its Composite I. Moisture Effects on Dipole Relaxation , Journal of Applied Polymer Science, 31: 1771–1784 .

16.

16. Senturia, S. and Sheppard, N. (1986). Dielectric Analysis of Thermoset Cure, In: Advances in Polymer Science, Vol. 80, pp. 3–44, Springer-Verlag, Berlin .

17.

17. Senturia, S.D., Sheppard, N.F., Jr., Lee, H.L. and Day, D.R. (1982). In-Situ Measurement of the Properties of Curing Systems With Microdielectrometry , Journal of Adhesion, 15: 69–90 .

18.

18. Sheppard, N.F., Day, D.D., Lee, H.L. and Senturia, S.D. (1982). Microdielectrometry , Sensors and Actuators, 2: 263–274 .

19.

19. Shirell, C.D. and Halpin, J. (1997). Moisture Absorption and Desorption in Epoxy Composite Laminates, ASTM STP 617, ASTM, Philadelphia , pp. 514–528.

20.

20. Zhang, J.S., Karbhari, V.M., Isley, F. and Neuner, J., Fiber Sizing Based Enhancement of Materials Durability for Seismic Retrofit , ASCE Journal of Composites for Construction (in press).