Strain rate sensitivity of polyetheretherketone's compressive yield stress at low and high temperatures

• PEEK yield stress is measured at low and high temperatures.
• The yield stress sensitivity is more important at low temperatures.
• The activation volume and activation energy are calculated.
• New equation is proposed to model temperature and strain rate sensitivities.

The yield stress of polyetheretherketone (PEEK) is investigated over a wide range of temperatures (from 143 to 473 K), covering the glass transition range, at three strain rates: 0.001, 0.1 and 5/s. This work completes a previous experimental work (El-Qoubaa and Othman, 2015a) which characterizes and models the PEEK's yield stress behavior at room temperature over a wide range of strain rate (from 0.0001 to 10,000/s). The yield stress is observed to be sensitive to the strain rate and temperature. The sensitivity to the strain rate is more important at low temperatures and high strain rates. Moreover, the yield stress decreases as temperature increases. This decrease is more important in the low temperature range. The yield stress sharply drops as temperature crosses the glass transition. A new constitutive equation is established for the yield stress. It fits well the experimental values over the studied ranges of temperatures and strain rates.

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