Advertisement

Journal of Materials Science

, Volume 44, Issue 5, pp 1333–1343 | Cite as

Effect of fibre concentration, strain rate and weldline on mechanical properties of injection-moulded short glass fibre reinforced thermoplastic polyurethane

  • S. Wilberforce
  • S. HashemiEmail author
Article

Abstract

The effect of fibre concentration, strain rate and weldline on tensile strength, tensile modulus and fracture toughness of injection-moulded thermoplastic polyurethane (TPU) reinforced with different concentration levels of short glass fibres was investigated. It was found that tensile strength, σc, of single-gated mouldings increased with increasing volume fraction of fibres, ϕf, according to a second order polynomial function of the form \( \sigma_{\text{c}} = a_{0} + a_{1} \phi_{\text{f}} + a_{2} \phi_{\text{f}}^{2} \) and increased linearly with natural logarithm of strain rate (\( { \ln }\,\dot{e} \)). Tensile modulus and fracture toughness (at initiation) of single-gated mouldings increased linearly with increasing ϕf (rule-of-mixtures) and \( { \ln }\,\dot{e} \). A linear dependence was obtained between fibre efficiency parameter for composite modulus, ηE, and \( { \ln }\,\dot{e} \). The presence of weldline in double-gated mouldings reduced tensile strength, tensile modulus and fracture toughness of TPU composites but had no significant effect upon properties of the TPU matrix. All the aforementioned properties increased with increasing fibre concentration and showed a linear dependence with respect to \( { \ln }\,\dot{e} \). Weldline integrity factor for all three properties decreased with increasing fibre concentration showing no strain-rate effect of any significance. Results indicated that tensile strength was more affected by the presence of weldline than tensile modulus or fracture toughness. It was noted that composite properties in the presence of weldline were still much greater than those for the unweld matrix. Weldline integrity values close to unity indicated that measured properties for the matrix were not significantly affected by the weldline.

Keywords

Tensile Strength Fracture Toughness Tensile Modulus Fibre Concentration Thermoplastic Polyurethane 

References

  1. 1.
    Hashemi S, Gilbride MT, Hodgkinson JM (1996) J Mater Sci 31:5017. doi: https://doi.org/10.1007/BF00355900 CrossRefGoogle Scholar
  2. 2.
    Din KJ, Hashemi S (1997) J Mater Sci 32:375. doi: https://doi.org/10.1023/A:1018553400266 CrossRefGoogle Scholar
  3. 3.
    Chrysostomou A, Hashemi S (1998) J Mater Sci 33:1165. doi: https://doi.org/10.1023/A:1004365323620 CrossRefGoogle Scholar
  4. 4.
    Chrysostomou A, Hashemi S (1998) J Mater Sci 33:4491. doi: https://doi.org/10.1023/A:1004487814709 CrossRefGoogle Scholar
  5. 5.
    Nabi ZU, Hashemi S (1998) J Mater Sci 33:2985. doi: https://doi.org/10.1023/A:1004362915713 CrossRefGoogle Scholar
  6. 6.
    Hashemi S (2002) J Plast Rubber Compos 31:1CrossRefGoogle Scholar
  7. 7.
    Hashemi S, Lepessova Y (2007) J Mater Sci 42:2652. doi: https://doi.org/10.1007/s10853-006-1358-z CrossRefGoogle Scholar
  8. 8.
    Necar M, Irfan-ul-Haq M, Khan Z (2003) J Mater Process Technol 142:247CrossRefGoogle Scholar
  9. 9.
    Fu SY, Lauke B, Mader E, Yue CY, Hu X (2000) Composites A31:1117CrossRefGoogle Scholar
  10. 10.
    Fisa B (1985) Polym Compos 6:232CrossRefGoogle Scholar
  11. 11.
    Thomason JL (2002) Compos Sci Technol 62:1455CrossRefGoogle Scholar
  12. 12.
    Thomason JL (2001) Compos Sci Technol 61:2007CrossRefGoogle Scholar
  13. 13.
    Mouhmid B, Imad A, Benseddiq N, Benmedakhene S, Maazouz A (2006) Polym Testing 25:544CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.London Metropolitan Polymer CentreLondon Metropolitan UniversityLondonUK

Personalised recommendations