A constitutive model of polyether-ether-ketone (PEEK)

A modified Johnson–Cook (JC) model was proposed to describe the flow behaviour of polyether-ether-ketone (PEEK) with the consideration of coupled effects of strain, strain rate and temperature. As compared to traditional JC model, the modified one has better ability to predict the flow behaviour at elevated temperature conditions. In particular, the yield stress was found to be inversely proportional to temperature from the predictions of the proposed model

3D printing of PEEK-based medical devices

open access articlePolyether-ether-ketone (PEEK) is an excellent thermoplastic alternative to metallic biomaterials which is used for loadbearing applications due to its high strength and stiffness, and biocompatibility with no cytotoxic effects. However, a potential clinical concern is that PEEK alone is not bioactive enough, and thus has limited fixation to bone. To overcome this problem, bioactive materials and/or porosity are incorporated into PEEK medical devices. The latest developments in these two strategies are presented. in this paper. Bioactive PEEK/hydroxyapatite (HA) prepared by integration of 3D printing and compression molding is presented in this paper. In addition, nozzle and build plate temperatures for 3D printing of porous PEEK were optimized using genetic algorithm (GA) to achieve the highest mechanical strength for load bearing applications such as spinal fusion cages

LUBRICATION OF POLYETHER ETHER KETONE (PEEK)

Master'sMASTER OF ENGINEERIN

Mechanical impact behavior of polyether-ether-ketone (PEEK)

This paper deals with the mechanical behavior of polyether ether ketone (PEEK) under impact loading. PEEK polymers are the great interested in the field of medical implants due to their biocompatibility, weight reduction, radiology advantage and 3D printing properties. Implant applications can involve impact loading during useful life and medical installation, such as hip systems, bone anchors and cranial prostheses. In this work, the mechanical impact behavior of PEEK is compared with Ti6AI4V titanium alloy commonly used for medical applications. In order to calculate the kinetic energy absorption in the impact process, perforation tests have been conducted on plates of both materials using steel spheres of 1.3 g mass as rigid penetrators. The perforation test covered impact kinetic energies from 21 J to 131 J, the equivalent range observed in a fall, an accidental impact or a bike accident. At all impact energies, the ductile process of PEEK plates was noted and no evidence of brittle failure was observed. Numerical modeling that includes rate dependent material is presented and validated with experimental data.The researchers of the University Carlos Ill of Madrid are indebted to Ministerio de Ciencia e lnnovación de España (Project DPl/2011 24068) for the financial support received which allowed conducting part of this work

Detection of Thermoluminescence in Polyether Ether Ketone (PEEK)

Sterilization is a mandatory process for materials used in medical applications. Sterilization procedures commonly used are steam sterilization, ethylene oxide (EtO) sterilization and sterilization by radiation. The high energy photons incident upon a polymer can cause chain scission, crosslinking, defects (trapped electrons) within the polymer matrix, and the formation of free radicals. In this research work, we used thermally stimulated luminescence (TSL) and differential scanning calorimeter (DSC) to study the effects of X- and UV-irradiation on different grades of PEEK. We have observed a major sharp glow peak at temperature of about 150°C (with other five minor peaks), at the glass transition temperature of PEEK, similar to previous researchers. After X- and UV- irradiation the peak at about 100°C is much more affected by radiation. Initially, its intensity increases rapidly with the time of exposure to radiation and then increases slowly. Also, the observation showed that, after irradiation the intensity of peak at 100ºC decreases rapidly as the time passes and the effect of radiation persists for only about 24 hours after irradiation. The PEEK polymer is affected more by X-ray in comparison with UV-radiation. TSL of preheated samples of PEEK shows glow peak at about 75ºC and its intensity is found to increase with increase in preheat temperature. Moreover, the initial major TSL peak at about 150ºC completely disappear when the PEEK (film) is preheated at 250ºC for one hour in air and it reappears again as the sample is stored for longer time (within one day) at room temperature. DSC measurement shows a large exothermic crystallization peak at temperature 180 for PEEK film. This indicates that material has a strong tendency to crystallize. We observed that the glass transition temperature (Tg) increases and melting temperature (Tm) decreases slightly as a result of X-irradiation for all types of PEEK. Similar observations were made by past researcher in PEEK for γ- and e-beam irradiation. The shift of Tg to higher temperature and Tm to lower temperature with irradiation suggest that both cross-linking as well as chain scission mechanisms take place due to X-irradiation

Detection of Thermoluminescence in Polyether Ether Ketone (PEEK)

Sterilization is a mandatory process for materials used in medical applications. Sterilization procedures commonly used are steam sterilization, ethylene oxide (EtO) sterilization and sterilization by radiation. The high energy photons incident upon a polymer can cause chain scission, crosslinking, defects (trapped electrons) within the polymer matrix, and the formation of free radicals. In this research work, we used thermally stimulated luminescence (TSL) and differential scanning calorimeter (DSC) to study the effects of X- and UV-irradiation on different grades of PEEK. We have observed a major sharp glow peak at temperature of about 150°C (with other five minor peaks), at the glass transition temperature of PEEK, similar to previous researchers. After X- and UV- irradiation the peak at about 100°C is much more affected by radiation. Initially, its intensity increases rapidly with the time of exposure to radiation and then increases slowly. Also, the observation showed that, after irradiation the intensity of peak at 100ºC decreases rapidly as the time passes and the effect of radiation persists for only about 24 hours after irradiation. The PEEK polymer is affected more by X-ray in comparison with UV-radiation. TSL of preheated samples of PEEK shows glow peak at about 75ºC and its intensity is found to increase with increase in preheat temperature. Moreover, the initial major TSL peak at about 150ºC completely disappear when the PEEK (film) is preheated at 250ºC for one hour in air and it reappears again as the sample is stored for longer time (within one day) at room temperature. DSC measurement shows a large exothermic crystallization peak at temperature 180 for PEEK film. This indicates that material has a strong tendency to crystallize. We observed that the glass transition temperature (Tg) increases and melting temperature (Tm) decreases slightly as a result of X-irradiation for all types of PEEK. Similar observations were made by past researcher in PEEK for γ- and e-beam irradiation. The shift of Tg to higher temperature and Tm to lower temperature with irradiation suggest that both cross-linking as well as chain scission mechanisms take place due to X-irradiation

Thermo-Mechanical Behavior of Poly(ether ether ketone): Experiments and Modeling

Observations are reported on poly(ether ether ketone) (PEEK) in uniaxial tensile tests, relaxation tests and creep tests with various stresses in a wide interval of temperatures ranging from room temperature to 180 °C. Constitutive equations are developed for the thermo–mechanical behavior of PEEK under uniaxial deformation. Adjustable parameters in the governing equations are found by matching the experimental data. Good agreement is demonstrated between the observations and results of numerical simulation. It is shown that the activation energies for the elastoplastic, viscoelastic and viscoelastoplastic responses adopt similar values at temperatures above the glass transition point

Hot tensile fracture characteristics and constitutive modelling of polyether-ether-ketone (PEEK)

The effects of strain rate and deformation temperature on the deformation behaviors of polyether-ether-ketone (PEEK) were studied by uniaxial tensile tests with the temperature range of 23–150 °C and strain rate of 0.01–1 s−1. The effects of deformation temperature and strain rate on the hot tensile deformation behavior and fracture characteristics were investigated by scanning electron microscope (SEM) and discussed in detail. SEM experimental results suggest that fracture morphology is not strain rate sensitive but temperature sensitive. Based on the tensile results, the Johnson-Cook and modified Johnson-Cook constitutive models were established for PEEK. Furthermore, a comparative study has been made on the accuracy and effectiveness of the developed models to predict the flow stress. The results show that the original Johnson-Cook model reflects the deformation behavior more accurately throughout the entire test temperature and strain rate range under uniaxial tensile conditions