Polyetheretherketone Composites Research Articles

RETRACTED ARTICLE:3D printing of surface characterisation and finite element analysis improvement of PEEK-HAP-GO in bone implant

Research and development of polyetheretherketone (PEEK) composites with high thermal conductivities and ideal thermal stabilities have become one of the hot topics in composites. However, not all PEEK composites have the necessary characteristics adequate fracture toughness to resist forces and crack propagation , with an improved mechanical and structural properties. This research evaluates a novel computational surface characterisation and finite element analysis (FEA) of polyetheretherketone and hydroxyapatite graphene oxide (PEEK-HAP-GO) in the process of 3D printing to improve fracture toughness to resist forces and crack propagation . It also focuses on increasing the hydrophilicity, surface roughness, and coating osteoconductive of PEEK-HAP-GO for the bone implant. Compression and tensile tests were performed to investigate the mechanical properties of the PEEK-HAP-GO structure. The addition of calcium phosphate and the incorporation of porosity in PEEK-HAP-GO has been identified as an effective way to improve the osseointegration of bone-implant interfaces of PEEK-HAP-GO. The further analytical structure of the particle was performed, evaluating the surface luminance structure and the profile structure of composite material in 3D printing, analysing the profile curve of the nanostructure from the scanning electron microscope (SEM). The results of the uniaxial compression tests in new PEEK-HAP-GO biodegradable materials show good compressive strength suitable for loading applications. It shows melt-blending with bioactive nanoparticles can be used to produce bioactive nanocomposites like HAP-GO and is used to modify the surface structure of PEEK implants in order to make it more bioactive.

Compatibilization of clays and hydrophobic polymers: the case of montmorillonite and polyetheretherketone

In the last three decades, nanoclay fillers have been increasingly used to improve the mechanical, thermal, barrier and biological properties of the polymers. Nevertheless, incorporation of clays into the hydrophobic polymer matrices leads to the formation of the microcomposites with the minimal improvement in properties. To overcome the intrinsic incompatibility between the clays and the hydrophobic polymers, clay particles are organophilized using organic modifiers. The organic modifier should be thermodynamically miscible with the polymer. In the case of the composites prepared at high temperatures, the organic modifier should also have a high thermal stability to withstand the processing temperature. Taking into account these requisites, this study proposes a novel procedure for screening the diverse sets of the ionic liquids to find the most appropriate organic modifiers for compatibilization of the clays and any given hydrophobic polymers. The proposed procedure has been used to find the appropriate organic modifier to compatibilize montmorillonite clay (MMT) and polyetheretherketone (PEEK). Composites of PEEK filled with MMT and the organically modified MMT (OMMT) were synthesized via melt compounding. Then, they were characterized by FTIR, XRD and TEM. The results showed that the selected organic modifier satisfied both the processing requirements and the thermodynamic considerations and improved the dispersion of MMT particles within the PEEK matrix. The XRD patterns and TEM micrographs confirmed the formation of the PEEK/OMMT nanocomposite with intercalated/exfoliated morphology. The findings of this study provide a practical means for compatibilization of immiscible clays and polymers.

The effect of annealing on the behavior of polyetheretherketone composites compared to pure titanium

Polyetheretherketone (PEEK) has become increasingly popular in biomedical applications due to its favorable biocompatibility, biostability, mechanical strength, and elastic modulus, all of which are similar to those of natural bones. This paper investigates the effects of annealing on the behavior of PEEK ternary composites. PEEK samples were annealed and characterized by mechanical tests, Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive x-ray Spectroscopy (EDS) and physical property testing. Results showed that annealing has an appositive effect on the properties of PEEK. The properties of the ternary composites were also compared with those of pure PEEK and Ti as a control.

Synthesis and characterization of Sr-doped HAp-incorporated polyether ether ketone composite

Hydrothermally synthesized undoped and Sr-doped hydroxyapatite-dispersed polyether ether ketone composites has been fabricated by using hot isostatic pressing technique with 5, 10, 15, and 20 wt.% as the dispersoids content. The detailed structural investigation of the fabricated composites has been performed by scanning electron microscope, high-resolution transmission electron microscope, and X-ray diffraction technique that confirmed the uniform dispersion of the dispersoids with the polyether ether ketone matrix. The microindentation measurements show that the mechanical properties of the polyether ether ketone matrix improved remarkably with incorporation of the hydroxyapatite (HAp) particles. The nondestructively evaluated elastic modulus so obtained for the matrix and composites were further validated through finite element analysis. Moreover, the in vitro cytotoxic of the fabricated nanocomposites were also evaluated to assess its potential as a bioactive material.

Novel PEEK Copolymer Synthesis and Biosafety - I: Cytotoxicity Evaluation for Clinical Application.

In this research, we synthesized novel polyetheretherketone (PEEK) copolymers and evaluated the biosafety and cytotoxicity of their composites for spinal cage applications in the orthopedic field. The PEEK copolymers and their composites were prepared through a solution polymerization method using diphenyl sulfone as a polymerization solvent. The composite of PEEK copolymer showed good mechanical properties similar to that of natural bone, and also showed good thermal characteristics for the processing of clinical use as spine cage. The results of an in vitro cytotoxicity test did not show any evidence of a toxic effect on the novel PEEK composite. On the basis of these cytotoxicity test results, the PEEK composite also proved its in vitro biosafety for application to an implantable spine cage.

Mid-IR Laser Generating Ultrasound in a Polyetheretherketone Polymer

We demonstrate laser ultrasonic generation in polyetheretherketone (PEEK). A middle infrared ZnGeP2 optical parametric oscillator (ZGP-OPO) pumped by a Q-switched Ho:YAG laser is employed as the ultrasonic excitation source. The ZGP-OPO has a spectral range of 3.2–3.4 μm. At an output wavelength of 3.4 μm, the maximum average output power of ZGP-OPO is 3.05 W with a pulse width of 24.3 ns, corresponding to a peak power of approximately 127.5 kW. The ultrasound is generated by the laser converted from 3.2 to 3.4 μm in the PEEK composite. The maximum ultrasonic signal amplitude in PEEK is 33 mV under the condition of thermoelastic excitation at 3.4 μm. Ablation occurs in the CPRF sample when the energy fluence is over 122.45 mJ/cm2. PEEK has a stronger absorption at 3.4 μm and laser-ultrasound generation is influenced by the wavelength of the laser.

Enhanced interfacial strength of carbon fiber/PEEK composites using a facile approach via PEI&ZIF-67 synergistic modification

As a kind of metal-organic frameworks (MOFs) which possess large specific surface area and excellent thermal stability, zeolitic imidazolate framework-67 (ZIF-67) shows great application potentials because it can be synthesized in aqueous solutions at room temperature. In this work, we propose a synergistic strategy by taking advantages of polyetherimide (PEI) and ZIF-67 to enhance the interfacial strength of carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites via a facile route. The bare CF is simply immersed into PEI solution and the aqueous solution of ZIF-67 precursors stepwise at room temperature to wrap PEI intermediate sizing layer and in situ grow ZIF-67 crystals. The surface morphology of CF indicates that regulating the concentration of PEI sizing agents can control the relative amount of ZIF-67 adhered onto CF surface. After modification, the tensile strength of single CF shows no deterioration and the interfacial shear strength (IFSS) of as-prepared modified CF/PEEK reveals an increase of 40.5%. Besides, the enhanced interfacial interaction mechanism might be ascribed to miscible feature of PEI with PEEK and rough structure from ZIF-67. This work may shed some light on establishing a facile and effective synthetic approach to modify CF and improve the performance of composites without degrading the mechanical property of pristine CF.

The effect of hexagonal boron nitride on wear resistance under two and three-body abrasion modes of polyetherketone composites

This investigation was performed to study the effect of hexagonal boron nitride (hBN) on abrasion wear behaviour of polyetherketone (PEK) composites. PEK composite were examined for two-body abrasive wear (2-BAW) with silicon carbide abrasive paper and three-body abrasive wear (3-BAW) test with silica sand according to ASTM standards. The Taguchi L9 design of experiment was employed to optimize the wear operating parameters. The optimized conditions with 10 N load, 320 grit size and 10 wt% of hBN resulted minimum specific wear rate (Ks). Unfilled PEK portrayed better impact strength, hardness, lower density and lower Ks under 3-BAW. However, 10 wt% of hBN was beneficial under 2-BAW condition. The SEM micrographs were analyzed to probe the wear mechanism involved in the abrasion process. Surface roughness (Ra) value measured was compared with Atomic Force Microscopy (AFM) and it was found that both the values are in good agreement. Multi-objective optimization by ratio analysis (MOORA) was implemented to rank the overall performance of PEK composites under study.

Low dielectric loss LNT/PEEK composites with high mechanical strength and dielectric thermal stability

Abstract(3‐Aminopropyl)triethoxysilane treated La(2−x)/3Na0.06TiO3(x = 0.06) (LNT) microparticles filled polyetheretherketone (PEEK) composites were prepared using hot pressing process. The effects of variation of LNT ceramic filling fraction on dielectric properties, water absorption, thermal stability and mechanical strength were investigated. All composites demonstrate low water absorption (less than 0.4%) when the ceramic filling fraction is lower than 0.6Vf. The obtained composites exhibited dielectric permittivities varying from ~4 to ~22 as the ceramic fillers increased from 0.1 to 0.8Vfand low losses (~10−4@1 MHz, 3~5 × 10−3at the frequencies of microwave (10 GHz) and millimeter wave (29‐50 GHz), respectively). The mechanical strength, dimensional and dielectric thermal stability of the composite are remarkably improved by the addition of LNT ceramic fillers. A composite with near zero temperature coefficients of dielectric permittivity or resonant frequency and flexural strength of ~140 MPa could be obtained. The out‐of‐plane coefficient of thermal expansion (CTE) could be reduced to ~20 ppm/°C as the ceramic filler loading reached 0.7Vf.

PEEK composites with polyimide sizing SCF as reinforcement: Preparation, characterization, and mechanical properties

In this work, the surface modification of short carbon fibers (SCFs) using polyimide (PI) as a sizing agent was conducted and fully characterized, and SCF-reinforced polyether ether ketone (PEEK) composites were obtained by extrusion and injection molding. The surface characteristics of the PI-coated SCFs were evaluated using scanning electron microscopy and X-ray photoelectron spectroscopy. The results indicated that a uniform PI sizing layer was formed on the surfaces of the SCFs. Thermogravimetric analysis results demonstrated that PI-coated SCFs had better thermal stability than commercial SCFs. The tensile strength and flexural strength of the PI-coated SCF/PEEK composites showed improvements of 11.8% and 16.6% compared with the commercial cases, which were attributed to the PI sizing treatment effectively improving the interfacial adhesion between the SCF and the PEEK matrix. Dynamic mechanical analysis and the morphologies of tensile fracture surfaces suggested better interfacial adhesion between the fibers and the PEEK matrix, which were in good agreement with the mechanical properties. Due to the convenient processing of PI sizing as well as the effectively improved mechanical properties of the composites, the PI-sizing methodology has great potential application in the field of fiber-reinforced high-temperature engineering plastics composites.

PEEK composites with polyimide sizing SCF as reinforcement: Preparation, characterization, and mechanical properties:

In this work, the surface modification of short carbon fibers (SCFs) using polyimide (PI) as a sizing agent was conducted and fully characterized, and SCF-reinforced polyether ether ketone (PEEK) c...

Effect of tool temperature on dimensional fidelity and strength of thermoformed polyetheretherketone composites

AbstractThis article presents an experimental study of the effect of tool/consolidation temperature on dimensional fidelity and curved beam strength of thermoformed carbon/PEEK composites made of continuous fibers and random oriented strands (ROS). When processing continuous fiber carbon/PEEK composites, higher tool/consolidation temperatures give higher curved beam and inter‐ply strength and more repeatable process induced deformations. Spring‐in increases with tool temperature but the spring‐in is repeatable and flange warpage is reduced because of lower resin viscosity and increased material flow during consolidation. For the ROS material form, no increase in curved beam strength was observed with higher consolidation temperatures and failure was not governed by the inter‐ply strength of the laminate because of the shorter fibers. Lower tool/consolidation temperatures gave less spring‐in and flange warpage was not dependent on consolidation temperature. Spring‐in for both material forms was found to be thermo‐elastic with no effects from crystallization shrinkage.

Synergistic effect of hydrogen bonding and π-π stacking in interface of CF/PEEK composites

Due to the extraordinary thermal stability, chemical resistance and processability, carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites are widely applied in aviation, aerospace, medical fields, etc. However, the non-polar nature and low wettability of CFs limited the interfacial bonding between CFs and PEEK and results in unsatisfied mechanical properties for CF/PEEK composites. In order to enhance interactions between fibers and matrix, the interface in CF/PEEK composites was built through coating a mixture of polyetherimide (PEI) and functionalized multi-walled carbon nanotubes (COOH-MWCNTs) on CFs. The combination of hydrogen bonding between COOH-MWCNT and PEI as well as the π-π interaction between PEI and PEEK significantly improved the miscibility and interfacial interlocking. As a result, the flexural strength, modulus and interlaminar shear strength (ILSS) of modified CF/PEEK were remarkably improved by 76% (667.8 MPa), 119% (40.0 GPa), and 85% (90.7 MPa) respectively. The failure mechanism changed from smooth cracking in interface destruction to zigzag cracking and resin breakage, suggesting that the resultant interface became strong enough to ensure efficient stress transfer from PEEK to CF. The synergistic interfacial interactions via hydrogen bonding and pi-pi stacking are believed to supply an effective strategy for building high-performance thermoplastic composites.

Friction and wear behaviours of self-lubricating peek composites for articulating pin joints

With the rapid development of engineering materials, self-lubricating and high strength composites have become a high demand candidate material for pin joints due to their significant potential in downsizing and weight saving. In this study, bearing bushes made from unfilled polyetheretherketone (PEEK) and PEEK composites were investigated for their tribological performance through two sets of experiments, (i) ball-on-disc dry sliding on CETR UMT, and (ii) pin/bush contact on a purpose built pin joint test rig. Continuous rotation and oscillation of shaft were performed with the pin/bush contact configuration. The contact pressure between the bush and shaft ranged from 20 MPa to 140 MPa and articulation speed from 10 deg/s to 60 deg/s. Wear mechanism was investigated through microscopic observation.

Super tough graphene oxide reinforced polyetheretherketone for potential hard tissue repair applications

Biocompatible polyetheretherketone (PEEK) is a favorable material for hard tissue repair due to its similar elastic modulus to that of the human bone. In this work, graphene oxide (GO) reinforced PEEK nanocomposites with different GO loading have been prepared by injection molding. Mechanical testing reveals that the toughness of the reinforced composite varies with the GO loading, with 0.5% GO giving the greatest elongation at break (86.32% greater than pristine PEEK). The underlying toughening mechanism has been attributed to the well-dispersed GO forming π-π* conjugations at the GO/PEEK interface. These conjugations also acted as the nucleation sites for oriented crystallized region in PEEK. As the GO content increases further (e.g > 0.5%), the fillers tend to agglomerate and would disturb the crystallites of PEEK and serve as stress concentration sites, resulting in decreased toughness. The biocompatibility of the composites has been evaluated in vitro, and the results showed that the addition of GO into PEEK favors the adhesion and spreading of bone marrow stromal stem cells, demonstrating the strong potential of our GO reinforced PEEK composites in applications such as hard tissue repair and replacement.

Effect of fiber reinforcement and fabrication process on the dynamic compressive behavior of PEEK composites

This paper investigates experimentally the dynamic compressive behavior of short fiber reinforced polyetheretherketone (PEEK) composites, with a specific focus on the effect of strain rate, fiber reinforcement and fabrication process. Hopkinson compressive bar system is employed to test the specimens with strain rate varies from 800–2500/s. Ultra-high speed camera system is used to record the deformation and failure process. Scanning electron microscopy (SEM) is introduced to examine the fracture surface, and to analyze the failure mechanism and its rate dependency. Three different types of PEEK composites are studied and compared to investigate the sensitivity of failure mechanism to fiber reinforcement and fabrication method (injection and extrusion). The results indicate that the ultimate stresses of PEEK and PEEK composites present different levels of sensitivity against strain rates, while the failure strain of PEEK composites decrease with the increase of strain rate. The strain rate dependency is associated with the increase of interface toughness under higher strain rate. The experimental results also identify the presence of phase transformation for matrix material during the high-rate compressive failure. The sensitivity of failure behavior against fabrication process is found to associate with the difference of fiber distributions.

Higher mechanical performances of CF/PEEK composite laminates via reducing interlayer porosity based on the affinity of functional s‐PEEK

Extensive application of carbon fiber‐reinforced thermoplastic composites has been severely limited by two essential drawbacks including poor interfacial adhesion and harmful void volume fraction between the fiber and the thermoplastic matrix. These drawbacks are due to the surface inertness and high viscosity of thermoplastic during the forming process, respectively. To address these challenges, we report a strategy in which sulfonated polyetheretherketone (s‐PEEK) with strong affinity was successfully obtained as a compatibilizer to modify the interfacial micromechanical properties of carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites. Using optimum mass amount of s‐PEEK, the interlaminar shear strength (ILSS) and tensile strength of the improved CF/PEEK composite laminates were 78.6 and 795 MPa, which had been increased more than 45.6% and 11.2% as compared with the original CF/PEEK composite laminates, respectively. The reason was that internal voids and interfacial bonding between CF and PEEK matrix were obviously improved by s‐PEEK. The affinity of s‐PEEK offered new insights to overcome the poor interfacial adhesion for fabricating structural parts with thermoplastic composites. The functionalized CF/PEEK composites have been successfully applied to fabricate a car interior ornament, well meeting the requirements of lightweight and high strength of automobiles. POLYM. COMPOS., 40:3749–3757, 2019. © 2019 Society of Plastics Engineers

Carbon Fiber Reinforced PEEK Composites Based on 3D-Printing Technology for Orthopedic and Dental Applications.

Fused deposition modeling (FDM) is a rapidly growing three-dimensional (3D) printing technology and has great potential in medicine. Polyether-ether-ketone (PEEK) is a biocompatible high-performance polymer, which is suitable to be used as an orthopedic/dental implant material. However, the mechanical properties and biocompatibility of FDM-printed PEEK and its composites are still not clear. In this study, FDM-printed pure PEEK and carbon fiber reinforced PEEK (CFR-PEEK) composite were successfully fabricated by FDM and characterized by mechanical tests. Moreover, the sample surfaces were modified with polishing and sandblasting methods to analyze the influence of surface roughness and topography on general biocompatibility (cytotoxicity) and cell adhesion. The results indicated that the printed CFR-PEEK samples had significantly higher general mechanical strengths than the printed pure PEEK (even though there was no statistical difference in compressive strength). Both PEEK and CFR-PEEK materials showed good biocompatibility with and without surface modification. Cell densities on the “as-printed” PEEK and the CFR-PEEK sample surfaces were significantly higher than on the corresponding polished and sandblasted samples. Therefore, the FDM-printed CFR-PEEK composite with proper mechanical strengths has potential as a biomaterial for bone grafting and tissue engineering applications.

Mechanical and wear properties of polyetheretherketone composites filled with basalt fibres

Abstract Polymers are widely used as replacements for machined metal components in engineering applications. To withstand extreme contact conditions, reinforcing materials are often introduced into polymers to improve their mechanical and wear properties. This paper investigates the applicability of basalt fibres as reinforcing materials to enhance the mechanical and wear properties of polyetheretherketone (PEEK). The weight percentage of short basalt fibres in PEEK composites was 0-10% based on the injection moulding method. The mechanical properties and tribological behaviours of the resulting composites were investigated. The results showed that the composites filled with basalt fibres exhibit significant improvements in strength, anti-indentation creep and hardness. Meanwhile, the friction coefficient and wear rate of the composites decreased obviously due to basalt fibres on the top of the worn surface bearing the dynamic load under sliding. The morphology of the worn surface indicates that fibre pull-out and fibre breakage both contribute to energy dissipation. However, the mechanical properties of the composites did not increase linearly with increasing fibre content because of the decreasing bonding force between the fibres and the matrix. These results are significant for the application of PEEK in engineering.

Engineering the mechanical properties of CNT/PEEK nanocomposites.

Poly-ether-ether-ketone (PEEK) was deeply investigated as a composite matrix because of its outstanding mechanical properties and thermostability. However, the performance improvement of fiber-reinforced PEEK composites was moderate according to a great number of experimental investigations. An insightful understanding of the deformation and interfacial failure in the PEEK composite is needed to guide the future fabrication of high-performance PEEK plastics. In this paper, Molecular Dynamics (MD) simulation was employed to evaluate the mechanical properties of carbon nanotube (CNT) reinforced PEEK nanocomposites. It was found that the weak interface between CNTs and the PEEK matrix leads to the flaws in the CNT/PEEK nanocomposite. A CNT-functionalization strategy was used to introduce H-bonds between CNTs and the PEEK matrix, improving the overall mechanical performance of the CNT/PEEK nanocomposite. Numerical examples validate that the addition of amino groups on CNTs can significantly improve the interfacial failure shear stress and elastic modulus of the CNT/PEEK nanocomposites. This mechanism study provides evidence and a theoretical basis to improve the mechanical performance of fiber-reinforced PEEK for lightweight structures in advanced equipment.