Static and dynamic uniaxial tensile responses were investigated to accurately characterize and predict the mechanical properties of PEEK (polyether-ether-ketone) at strain rates ranging from 10⁻³ s⁻¹ to 200 s⁻¹ and temperatures ranging from 23 °C to 110 °C. The tensile responses showed dependences on the strain rate and temperature, and the dependences of the yield strength and elastic modulus on the temperature and strain rate were studied. A modified phenomenological Sherwood–Frost constitutive model considering a wide range of strain rates and temperatures was established to characterize the tensile mechanical response of PEEK material before yielding based on the experimental data. The results indicate that the model can accurately describe the pre-yield behavior of PEEK under different temperature and strain rate conditions, thus reducing the dependency on experimental data for subsequent researchers, thereby providing a theoretical foundation and modeling framework for the design and performance evaluation of CF/PEEK composite structures.

Accurately characterizing the mechanical behavior of polyether ether ketone (PEEK) under low strain rate conditions and over a wide temperature range is essential for predicting the mechanical performance of PEEK and PEEK-based composites. In this study, PEEK grade ZYPEEK^®-330G was used. Specimens were prepared by injection molding. Quasi-static uniaxial tensile tests were conducted at temperatures of 20, 50, 80, 110, and 140 °C and strain rates from 10⁻⁴ to 10⁻¹ s⁻¹, with three replicate specimens for each condition. The high-temperature rheological behavior and flow stress below glass transition temperature (Tg ≈ 143 °C) were studied based on the free volume theory. Results indicate that with the increasing of temperature and the decreasing of strain rate, the yield strength, flow stress and elastic modulus of PEEK decrease, while the ductility and toughness are enhanced. The strain rate sensitivity index demonstrates a transition trend from non-Newtonian flow to Newtonian flow below Tg. A seven-parameter modified constitutive model considering both strain rate and temperature effects is proposed to accurately characterize the tensile mechanical response of PEEK before yielding. Model parameters were determined from the true stress–strain data at 20, 80, 110, and 140 °C, and the model was independently validated against the 50 °C data not used for fitting, with a prediction error of less than 3%. The model is limited to the pre-yield regime, the quasi-static strain rate range of 10⁻⁴ to 10⁻¹ s⁻¹, and temperatures below Tg. These findings demonstrate that the tensile response of PEEK is sensitive to both temperature and strain rate, and this constitutive model provides a foundation for predicting the tensile behavior of PEEK under complex environmental conditions.