Main Article Content


Injection molded long fiber thermoplastic components are being used in recent days as a viable replacement for metals in many applications .Present work focus on the effect of fiber length on the short-term flexural creep performance of fiber reinforced thermoplastic polypropylene. Unreinforced polypropylene, 20 wt % short and 20 wt % long glass fiber reinforced polypropylene materials was injection-molded into flexural test specimens. Short-term flexural creep tests were performed for 2 h duration on molded specimen at various stress levels with the aid of in-house developed flexural creep fixture. Experimental creep performance of polypropylene composites for 2 h is utilized to predict the creep performance with the aid of four parameter HRZ model and compared with 24 h experimental creep data. Creep strain was found to be increased with respect to time for all the test materials and found to be sensitive with respect to the stress level. Test results also revealed that long fiber reinforced thermoplastic material possessed enhanced creep resistance over their counter parts and HRZ model is sufficient enough to predict creep performance of polypropylene composites over wide range of stress.


Injection molding flexural creep thermoplastic creep strain.

Article Details

How to Cite
Subramanian, C., Mamari, A. K. H. A., & Senthilvelan, S. (2015). Effect of Fiber Length on the Short-Term Flexural Creep Behavior of Polypropylene. Students’ Research in Technology & Management, 2(5), 157-162. Retrieved from


  1. J. Markarian, “Long fibre reinforcement drives automotive market forward”, Plastics, Additives and Compounding, Vol.7, pp.24-29, 2005.
  2. B.V. Gupta and J. Lahiri, “Non-linear viscoelastic behavior of polypropylene and glass reinforced polypropylene in creep,” Journal of Composite Materials, Vol.14, pp.288-296, 1980.
  3. Sepe, M.P. Use of advanced characterization techniques in evaluating the fitness-for-use of long-glass fiber thermoplastics: San Francisco, 1994, pp.2029-2032.
  4. S.R .Challa and R.C .Progelhof, “A study of creep and creep rupture of polycarbonate”, Polymer Engineering and Science, Vol.6, pp.546-554, 1995.
  5. A. Pegoretti and T.Ricco, “Creep crack growth in a short glass fibres reinforced polypropylene composite”, Journal of Material Science, Vol.19, pp.4637-4641, 2001.
  6. R.K. Krishnaswamy, “Analysis of ductile and brittle failures from creep rupture testing of high-density polyethylene (HDPE) pipes”, Polymer, Vol. 28, pp.11664 -11672, 2005.
  7. S.Houshyar , R.A.Shanks and A. Hodzic, “Tensile creep behavior of polypropylene fibre reinforced polypropylene composites”, Polymer Testing,Vol. 24,pp. 257-264,2005.
  8. A.Greco, Claudio Musardo and Alfonso Maffezzoli, “Flexural creep behaviour of PP matrix woven composite”, Composites Science and Technology, Vol.67, pp.1148-1158, 2007.
  9. B.A. Acha M.M.Reboredo, and N.E.Marcovich, “Creep and dynamic mechanical behavior of PP–jute composites: Effect of the interfacial adhesion”, Composites Part A: Applied Science and Manufacturing, Vol.33, pp.1507-1516, 2007.
  10. W.N. Findley and G. Khosla, “Application of the superposition principle and theories of mechanical equation of state, strain, and time hardening to creep of plastics under changing loads”, Journal of Applied Physics, Vol.26, pp.821–832,1955.
  11. W.J. Liou and C.I. Tseng, “Creep behavior of nylon-6 thermoplastic composites”, Polymer Composites, Vol.18, pp.492-499, 1997.
  12. M.Hadid, S.Rechak and A.Tati, “Long-term bending creep behavior prediction of injection molded composite using stress-time correspondence principle”, Materials Science and Engineering A, Vol.385, pp.54-58, 2004.
  13. G.E. Novak, “Creep fracture of long fiber reinforced nylon 66”, Polymer Composites, Vol.16, pp.38-51, 1995.
  14. K.Banik, J.Karger-Kocsis and T. Abraham, “Flexural creep of all-polypropylene composites: Model analysis”, Polymer Engineering Science, Vol.48, pp.941-948, 2008.
  15. H.Liu, M.A.Polak and A.Penlidis, “A practical approach to modeling time-dependent nonlinear creep behavior of polyethylene for structural applications”, Polymer Engineering Science, Vol.48, pp.159-167, 2008.
  16. American Society of Civil Engineers, Structural Plastic Design Manual, 1986.
  17. V.S.Chevali, D.R. Dean, and G.M. Janowski, “Flexural creep behavior of discontinuous thermoplastic composites: Non-linear viscoelastic modeling and time–temperature-stress superposition”, Composites: Part A, Vol. 40, pp. 870-877, 2009.
  18. “Twintex Product Data Sheet”, Long fiber thermoplastic pellets, 2005, USA.
  19. C.Subramanian and S.Senthilvelan, “Development and preliminary performance evaluation of discontinuous fiber reinforced thermoplastic leaf spring”, Journal of Materials: Design and Applications, Proc. of Ins. Mech. E Part L,Vol. 223(3), pp.131-142, 2009.
  20. “ASTM D-2990 Standard test methods for tensile, compressive, and flexural creep and creep-rupture of plastics”, ASTM International, Philadelphia.