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Journal of Materials Science

, Volume 43, Issue 13, pp 4423–4432 | Cite as

Effect of UV exposure on the microstructure and mechanical properties of long fiber thermoplastic (LFT) composites

  • A. Goel
  • K. K. ChawlaEmail author
  • U. K. Vaidya
  • M. Koopman
  • D. R. Dean
Commonality of Phenomena in Composite Materials

Abstract

In this work, the effect of ultraviolet (UV) exposure on the microstructure and dynamic Young’s modulus of polypropylene (PP)/21 vol.% E-glass LFT and neat PP was investigated. Microscopic observations revealed that the damage due to UV was confined to the surface region only in the form of surface cracking and exposure of fibers to the surface in the case of long fiber thermoplastic (LFT) and surface cracking in the case of neat PP. Fourier transform infrared spectroscopy showed that the crystallinity of PP in the damaged layer increased, both in neat PP as well as in LFT, with exposure time. This is due to chemicrystallization, which involves rearrangement of amorphous broken polymer chains into crystalline form. Crystallinity of PP in the damaged layer in LFT increased at a higher rate as compared to that in neat PP. Results of nanoindentation showed that the Young’s modulus of the PP in the damaged layer increased, with UV exposure time; the rate of modulus increase being higher in the case of LFT than in neat PP. Although the local Young’s modulus of the degraded layer increased, the dynamic Young’s modulus of the overall composite showed a decrease with UV exposure time.

Keywords

Contact Stiffness Transverse Crack Flexural Modulus Continuous Stiffness Measurement Unexposed Sample 

Notes

Acknowledgements

Financial support for this work was received from Federal Transit Administration (FTA), contract #AL-26-7022-02. Thanks are due to S.D. Bartus and S. Pillay for providing the LFT plates. Thanks are also due to K. Carlisle for helpful discussions.

References

  1. 1.
    Bartus SD, Vaidya UK (2005) Compos Struct 67:263CrossRefGoogle Scholar
  2. 2.
    Chawla KK (1998) Composite materials: science and engineering, 2nd edn. Springer-Verlag, New YorkCrossRefGoogle Scholar
  3. 3.
    Qureshi FS, Amin MB, Maadhah AG, Hamid SH (1990) J Polym Eng 9:67CrossRefGoogle Scholar
  4. 4.
    Yakimets I, Lai D, Guigon M (2004) Polym Degrad Stab 86:59CrossRefGoogle Scholar
  5. 5.
    Selden R, Nystrom B, Langstrom R (2004) Polym Compos 25:543CrossRefGoogle Scholar
  6. 6.
    Lundlin T, Cramer SM, Falk RH, Felton C (2004) J Mater Civil Eng 16:547CrossRefGoogle Scholar
  7. 7.
    Lundlin T, Falk RH, Felton C (2001) Proceedings of the 6th International Woodfiber-Plastic Composites Conference, Forest Products Society, May, Madison, Wisconsin, p 87Google Scholar
  8. 8.
    Rabello MS, White JR (1997) Polym Degrad Stab 56:55CrossRefGoogle Scholar
  9. 9.
    Larena A, Jiménez De Ochoa S, Domínguez F (2006) Polym Degrad Stab 91:940CrossRefGoogle Scholar
  10. 10.
    Rabello MS, White JR (1997) Polymer 38:6379CrossRefGoogle Scholar
  11. 11.
    White JR, Turnbull A (1994) J Mate Sci 29:584CrossRefGoogle Scholar
  12. 12.
    Oliver WC, Pharr GM (1992) J Mater Res 7:1564CrossRefGoogle Scholar
  13. 13.
    Li X, Bhushan B (2002) Mater Charact 48:11CrossRefGoogle Scholar
  14. 14.
    Simmons G, Wang H (1971) Single crystal elastic constants and calculated aggregate properties: a handbook. MIT Press, Cambridge, MAGoogle Scholar
  15. 15.
    Karger-Kocsis J (ed) (1999) Polypropylene: an A-Z reference. Kluwer Academic Publishers, The NetherlandsGoogle Scholar
  16. 16.
    ASTM E 1876–99 (1999) Annual book of ASTM standards. American Society for Testing and MaterialsGoogle Scholar
  17. 17.
    Tong L, White JR (1997) Polym Eng Sci 37:321CrossRefGoogle Scholar
  18. 18.
    Signor AW, Vanlandingham MR, Chin JW (2003) Polym Degrad Stab 79:359CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • A. Goel
    • 1
  • K. K. Chawla
    • 1
    Email author
  • U. K. Vaidya
    • 1
  • M. Koopman
    • 1
  • D. R. Dean
    • 1
  1. 1.Department of Materials Science and EngineeringUniversity of Alabama at BirminghamBirminghamUSA

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