Temperature and strain-rate effects on the fracture toughness of poly(ether ether ketone) and its short glass-fibre reinforced composite

J. Karger-Kocsis, K. Friedrich

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Constant-strain-rate mechanical testing and surface fractography were used for the fracture mechanical characterization of poly(ether ether ketone) (PEEK) and its short glass-fibre reinforced composite. Testing was performed as a function of temperature, strain rate and heat treatment. The fracture toughness of both materials is highly dependent on these factors causing either brittle or ductile damage. At high strain rate, a brittle-ductile transition was observed in the Kc-T curve of the PEEK matrix at 115°C. This could be interpreted as an isothermal-adiabatic transition superimposed on the glass transition. A similar, but less intense, transition was observed for the composite at higher temperaure (roughly at Tg = 144°C). This shift in the real Tg region of PEEK can be explained by the presence of fibres which enhance the thermal conductivity, thus acting as heat sinks and drastically reducing the adiabatic heating effects of the crack tip. Heat annealing caused an increase in the crystallinity and a decrease in the fracture toughness. Reasonable agreement was found between the Kc values derived from the established J integral and those measured.

Original languageEnglish
Pages (from-to)1753-1760
Number of pages8
Issue number11
Publication statusPublished - Nov 1986



  • composite
  • effects of temperature and strain rate
  • fibre reinforcing
  • fracture toughness
  • poly(ether ether ketone)

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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