Carbon Fiber Reinforced Polyetheretherketone Composites Research Articles

High-temperature fracture behavior of carbon fiber reinforced PEEK composites fabricated via fused filament fabrication

This study investigates the influence of temperature on the mechanical and fracture properties of carbon fiber reinforced (CF) polyetheretherketone (PEEK) composites, with a specific focus on different layer heights used in the additive manufacturing process. Tensile and compact tension fracture tests were conducted at varying temperatures to evaluate the orthotropic mechanical properties and crack growth resistance curves, respectively. The key findings underscore the pronounced orthotropic mechanical behavior in additively manufactured CF-PEEK composites, showing substantial variations of up to 50% in Young's modulus and yield strength across orientations. Additionally, as test temperatures increase, crack initiation becomes easier, indicating reduced crack resistance at elevated temperatures. Notably, the effect of layer height on initiation toughness is relatively minor compared to temperature. Moreover, the study reveals that fracture energy for crack growth is less temperature-sensitive but depends on layer height, with larger defects in taller layers resulting in decreased damage resistance. These findings stress the importance of considering the distinct sensitivities of initiation and steady-state fracture energies to temperature, emphasizing the critical role of effective fracture toughness in evaluating material resistance to high-temperature fractures. These observations contribute to our understanding of the mechanical and fracture behavior of CF-PEEK composites under high operating temperatures. This understanding facilitates the optimization of their manufacturing processes and their application in various industries such as aerospace.

The optimization of thermo-compression process parameters of continuous carbon fiber reinforced PEEK composites

Thermoplastic composites with high performance have become the primary material developed for aerospace applications. However, there are still numerous challenges for high-quality thermo-compression molding of thermoplastic composites. This paper investigated the control mechanism of porosity in continuous carbon fiber (CCF) reinforced polyether-ether-ketone (PEEK) composites based on an orthogonal molding scheme, which examines the effect of thermo-compression process parameters on porosity. Further insights were obtained regarding the correlation among molding process parameters, porosity, and mechanical properties. The experimental results indicated that the significant factors affecting the bending performance of CCF/PEEK composites were molding pressure, temperature, and sequence holding time. Moreover, the viscosity of molten PEEK resin significantly affected the porosity of the composites, and the descending order of effect on the porosity of the composites was molding temperature, holding time, and molding pressure. Based on these results, we identified the optimal molding process conditions for CCF/PEEK composites, which were 405 °C, 1.5 MPa, and 30 min.

Full-process multi-scale morphological and mechanical analyses of 3D printed short carbon fiber reinforced polyetheretherketone composites

3D printed short carbon fiber reinforced thermoplastic (SCFRTP) composites have complex multi-scale morphologies. These morphologies significantly affect the mechanical properties of SCFRTP. However, the existing research on multi-scale structural morphology formation and multi-scale mechanical responses of 3D printed SCFRTP composites is obviously insufficient so far. Herein, full-process multi-scale morphological and mechanical analyses of 3D printed SCFRTP composites are conducted in depth. Initially, the SCFRTP composites with the special engineering plastic polyetheretherketone (PEEK) as matrix and short carbon fiber (SCF) as filler (SCF contents of 1 wt%, 3 wt%, 5 wt%, 7 wt% and 10 wt%) are manufactured by 3D printing based on the principle of fused deposition modeling. The multi-scale structural morphologies of these composites are systematically characterized. Then, theoretical investigations are conducted to describe the flow behavior, crystallization and viscosity changes during 3D printing molding process, as well as the conservation of mass, momentum and energy for SCF/PEEK composites. The fluid-solid interaction numerical model is established to analyze the printing process of SCFRTP composites. Based on this model, the multi-scale morphologies of 3D printed SCFRTP composites are predicted, and the generation mechanism of multi-scale void defects in 3D printed SCFRTP composites is clarified. Subsequently, the multi-scale mechanical analysis of 3D printed SCFRTP composites is performed to predict the mechanical parameters of micro-traces, the performances of meso-layers and the mechanical properties of macro-3D printed SCFRTP specimens. The full-process from generation in manufacturing to evolution under tension of multi-scale void defects is described by the proposed model. The deviation between the experiment result and the numerical prediction which takes multi-scale void defects and fiber probability density distributions into account is much smaller compared with numerical results ignoring the multi-scale structures. Therefore, the full-process multi-scale analysis method proposed in this paper is of great significance to accurately predict the mechanical properties of 3D printed SCFRTP composites.

Strengthening and toughening behaviours and mechanisms of carbon fiber reinforced polyetheretherketone composites (CF/PEEK)

Carbon fiber reinforced polyetheretherketone (CF/PEEK) has vast application prospects in orthopedic implants. In practical applications, excellent tensile, bending and impact properties are indispensable for orthopedic implant materials. The pressure-induced flow (PIF) process markedly and simultaneously improved the strength and toughness of CF/PEEK by forming a multilayer-oriented structure, which controlled the propagation of cracks and the tortuous energy dissipating paths. In this paper, short carbon fiber (6 wt%) reinforced PEEK composites were molded at different desired temperatures and pressures to adjust the efficiency of mechanical enhancement. The mechanical properties of CF/PEEK samples were investigated, and the corresponding mechanisms for the improvement of mechanical properties were proposed. The results of the study showed that the maximum tensile strength, flexural strength and compact strength of the materials could reach 157.3 MPa, 382.0 MPa and 7.7 KJ/m2, respectively.

Osseointegration behavior of carbon fiber reinforced polyetheretherketone composites modified with amino groups: An in vivo study.

Polyetheretherketone (PEEK) has become increasingly popular in dentistry and orthopedics due to its excellent chemical stability, reliable biosafety, and low elastic modulus. However, PEEK's biomechanical strength and bioactivity are limited and need to be increased as an implant material. The previous study in vitro has shown that the amino-functionalized carbon fiber reinforced PEEK (A-30%-CPEEK) possessed enhanced mechanical property and bioactivity. This study aims to evaluate the effect of amino groups modification on the osseointegration behavior of carbon fiber reinforced PEEK (30%-CPEEK) in rabbits. Herein, 30%-CPEEK and A-30%-CPEEK implant discs were implanted in rabbit skulls for 5 weeks, with pure titanium implants serving as a control. The bone-forming ability and osseointegration in vivo were systematically investigated by micro-computed tomography analysis, scanning electron microscope observation, and histological evaluation. Our results showed that all detection parameters were significantly different between the A-30%-CPEEK and 30%-CPEEK groups, favoring those in the A-30%-CPEEK, whose appraisal parameters were equal to or better than pure titanium. Therefore, this study supported the importance of amino groups in facilitating the new bone formation and bone-implant integration, suggesting that A-30%-CPEEK with enhanced osseointegration will be a promising material for dental or orthopedic implants.

Damage performance in drilling of carbon fiber-reinforced polyetheretherketone composites using drills with different geometries

Damage performance in drilling of carbon fiber-reinforced polyetheretherketone composites using drills with different geometries

The interlaminar performance of carbon fiber reinforced polyetheretherketone composites reinforced by doped buckypaper

Carbon fiber reinforced polyetheretherketone (CF/PEEK) composites made by automated fiber placement (AFP) have interlaminar resin-rich zone defects, resulting in poor interlaminar mechanical performance. Buckypaper (BP) is a two-dimensional material made of carbon nanotubes (CNTs) with good mechanical properties that can be used as an interlaminar reinforcement phase. In this study, the molecular dynamics method is used to create a microscopic interface model for CF/PEEK/BP nanocomposites to calculate the interface bonding energy. Furthermore, the interlaminar shear strength is tested by the short beam method. The results reveal that there is a good interface bonding between BP and CF/PEEK. The CF/PEEK laminates doped with BP can improve the interlaminar shear strength by 22.6%. Therefore, the interlaminar doped BP can realize CF/PEEK components with better interlaminar mechanical performance based on the high efficiency of AFP, which can further improve the application of CF/PEEK composites in the field of aerospace.

Inherent relationship between process parameters, crystallization and mechanical properties of continuous carbon fiber reinforced PEEK composites

High-performance thermoplastic composites have been developed as significant structural materials for cutting-edge equipment in the aerospace and defence fields. However, the internal mechanism of processing parameters on mechanical properties in the manufacturing process of thermoplastic composite structures is still a serious challenge. The purpose of this study is to investigate the process/crystallization/property relationships for continuous carbon fiber (CF) reinforced polyether-ether-ketone (PEEK) composites. The composite laminates are fabricated according to orthogonal experiments via the thermoforming method. The mechanical performance is investigated in terms of crystallization properties and fracture morphology characterizations. Experimental results show that the mechanical performance and crystallization properties of thermoplastic composites are significantly affected by the coupling of processing parameters. The increased molding temperature, pressure, and holding time improve the degree of fiber/matrix infiltration and affect the crystallinity and crystalline morphology of the matrix, which further influences the mechanical properties of the composites. This is reflected in the test results that crystallinity has an approximately linear effect on mode-I interlaminar fracture toughness and transverse flexural modulus. As well as the higher molding temperature can destroy the pre-existent crystals to improve the toughness of the matrix, and the well-defined crystalline structures can be observed when fabricated at higher temperatures and longer periods of holding time.

The synergistic steric hindrance effect in the preparation of polyether ether ketone composites by powder slurry method

AbstractThe preparation of continuous carbon fiber reinforced polyether ether ketone (PEEK) composites by the powder slurry method has many advantages, but the stability of PEEK suspension is required to be high. So far, there is a lack of in‐depth studies on the aqueous suspension of PEEK. In this study, two non‐ionic surfactants were selected for compounding. Then PEEK aqueous suspension and continuous carbon fiber reinforced PEEK composites were prepared. The stability mechanism of PEEK aqueous suspension with different surfactants was analyzed. Studies have shown that in the PEEK aqueous suspension, Triton X‐100 can help to infiltrate the PEEK powder. The steric hindrance of polyethylene glycol contributes to the stability of the suspension. The synergistic steric hindrance effect of the two surfactants can increase the stability time of PEEK suspension from 5 min to more than 50 min. The PEEK composites prepared by the powder slurry method has good quality stability, the fiber volume fraction is about 60%, the flexural strength of the composites can reach 1336 MPa, and the interlayer shear strength can reach 106 MPa. This study provides useful insights for the stability mechanism of PEEK aqueous suspension, and can guide the preparation process of thermoplastic composites by powder slurry method.

Nanomechanical analysis of medical grade PEEK and carbon fiber-reinforced PEEK composites

Polyether ether ketone (PEEK) and PEEK composites are viable candidates for orthopedic implants owing to their ability for modulus match of surrounding bone tissue. The structural properties of these systems for load-bearing application in the body can be tailored by incorporating carbon fibers; to this end, polyacrylonitrile (PAN) and pitch fibers are commonly incorporated in the PEEK matrix. Mechanical property optimization for a given medical application requires consideration of carbon fiber type and volume fraction, as well as processing conditions for the composite systems. While much is known about the bulk mechanical properties of PEEK and PEEK composites, little is known about the nanomechanical properties of these systems. Insight into nanoscale behavior can offer valuable information about fiber-matrix interactions that may influence long-term integrity of these biomaterials when used in load bearing medical device applications. In this study, we utilize nanoindentation as a method to characterize mechanical behavior of clinical grade PEEK and PEEK composites. We examine PEEK formulations with pitch and PAN fibers and evaluate a range of thermal treatments known to influence polymer microstructure. We use a conospherical tip of 1.5 μm in radius and a conospherical tip of 20 μm radius to determine indentation modulus over different length scales. We correlate these findings with previous characterization on these same PEEK systems using microindentation. A novelty of this work is that we combine nanoindentation with k-means clustering to quantitatively discern the influence of heat treatment and carbon fiber type on the mechanical behavior of PEEK composites and their constituents. We demonstrate that nanoindentation is an effective characterization tool for discerning fiber-matrix interactions and measuring the mechanical behavior in response to thermal treatment and carbon fiber type in PEEK composites. Nanoindentation is shown to be a viable tool for characterizing complex biomaterials and can serve as an effective technique to guide optimization of microstructures for long-term structural applications in the body.

Enhanced bioactivity and osteogenic property of carbon fiber reinforced polyetheretherketone composites modified with amino groups

Polyetheretherketone (PEEK) is considered as a potential dental and orthopedic implant material owing to its favorable thermal and chemical stability, biocompatibility and mechanical properties. However, the inherent bio-inert and inferior osseointegration of PEEK have hampered its clinical application. In addition, carbon fiber is widely used as a filler to reinforce polymers for sturdy composites owing to its high strength, modulus, etc. In the study, carbon fiber reinforced PEEK (CPEEK) composites were fabricated and modified with amino groups by plasma-enhanced chemical vapor deposition surface modification technique. The surface characterization of composites was evaluated by FE-SEM, EDS, AFM, Water contact angle, XPS and FTIR, which revealed that amino groups were successfully incorporated on the modified CPEEK surface and significantly increased the hydrophilicity. In vitro study, cell adhesion, proliferation, ALP activity, ECM mineralization, real-time PCR analysis, and ELISA analysis showed the adhesion, proliferation and osteogenic differentiation of MG-63 cells on the amino group-modified CPEEK surface were higher than the CPEEK, equal to or better than pure titanium. Hence, the results indicated that the amino group-modified CPEEK possessed enhanced bioactivity and osteogenic property, which may be a potential candidate material for dental implants.

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.

Dynamic mechanical properties of carbon fibre-reinforced PEEK composites in simulated body-fluid

The work presents the fatigue mechanical properties of a composite material made of polyetheretherketone (PEEK) polymer and carbon fibres (CF) designed for structural biomaterials. Composite samples with various types of carbon fibre reinforcements were studied. The mechanical durability of the composite samples in simulated body solution was analysed. The samples were loaded for a predetermined number of cycles for various applied-force levels, at a frequency of 50Hz under a bending force, and at 1Hz under compression force. The mechanical changes were analysed taking into consideration the anisotropic structure of the composite samples made of fibre roving 1D, 2D tissue and carbon fibres in the form of braided fibre sleeves (MD). The ultrasonic method was applied to determine the changes in velocities measured in the composites. The average variations of mechanical stability of the composite samples kept in simulated body fluid were not significant after fatigue testing up to 1*106 cycles.

Tribological behavior of three‐dimensional braided carbon fiber reinforced polyetheretherketone composites

Three‐dimensional (3D) braided carbon fiber reinforced polyetheretherketone (denoted as CF3D/PEEK) composites with various fiber volume fractions were prepared via hybrid woven plus vacuum heat‐pressing technology and their tribological behaviors against steel counterpart with different normal loads at dry sliding were investigated. Contrast tribological tests with different lubricants (deionized water and sea water) and counterparts made from different materials (epoxy resin, PEEK) were also conducted. The results showed that the incorporation of 3D braided carbon fiber can greatly improve the tribological properties of PEEK over a certain range of carbon fiber volume fraction (Vf) and an optimum fiber loading of ∼54% exists. The friction coefficient of the CF3D/PEEK composites decreased from 0.195 to 0.173, while the specific wear rate increased from 1.48 × 10−7 to 1.78 × 10−7 mm3 Nm−1 with the normal load increasing from 50 to 150 N. Abrasive mechanism was dominated when the composites sliding with GCr15 steel counterpart under dry and aqueous lubrication conditions. Deionized water and sea water lubricants both significantly reduced the wear of the CF3D/PEEK composites. When sliding with neat PEEK counterpart, the CF3D/PEEK composites possess lower friction coefficient than those against epoxy resin and GCr15 steel counterparts. In general, CF3D/PEEK composites possess excellent tribological properties and comprehensive mechanical performance, which makes it become a potential candidate for special heat‐resisting tribological components. POLYM. COMPOS., 36:2174–2183, 2015. © 2014 Society of Plastics Engineers

Carbon fiber reinforced PEEK Optima—A composite material biomechanical properties and wear/debris characteristics of CF-PEEK composites for orthopedic trauma implants

BackgroundThe advantageous properties of carbon fiber reinforced polyetheretherketone (CF-PEEK) composites for use as orthopedic implants include similar modulus to bone and ability to withstand prolonged fatigue strain. MethodsThe CF-PEEK tibial nail, dynamic compression plate, proximal humeral plate and distal radius volar plate were compared biomechanically (by four-point bending, static torsion of the nail, and bending fatigue) and for wear/debris (by amount of the debris generated at the connection between the CF-PEEK plate and titanium alloy screws) to commercially available devices. ResultsFour-point bending stress of the tibial nail and dynamic and distal radius plates yielded characteristics similar to other commercially available devices. The distal volar plate bending structural stiffness of the CF-PEEK distal volar plate was 0.542Nm2 versus 0.376Nm2 for the DePuy's DVR anatomic volar plate. The PHILOS proximal humeral internal locking system stainless steel plate was much stronger (6.48Nm2) than the CF-PEEK proximal humeral plate (1.1Nm2). Tibial nail static torsion testing showed similar properties to other tested nails (Fixion, Zimmer and Synthes). All tested CF-PEEK devices underwent one million fatigue cycles without failure. Wear test showed a lower volume of generated particles in comparison to the common implants in use today. InterpretationThus, these tested implants were similar to commercially used devices and can be recommended for use as implants in orthopedic surgery.

Erosive wear properties of unidirectional carbon fiber reinforced PEEK composites

The erosive wear properties of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites were studied. A semi-ductile erosive wear manner was found regardless of the CF orientation. Wear mechanism analysis revealed that both cutting and deformation mechanisms existed in the erosion of the composites, although different damaging forms were involved depending on the impingement angles and CF orientation. To give further support on the erosion mechanisms, a special procedure was designed to observe the cross-sectional surface of the eroded composites, and the surface temperature variation was registered. It increased with increasing impingement angle, indicating higher energy dissipation by deformation, which is consistent with the revealed shift of the main erosive wear mechanism from cutting to deformation and “wholesale” fiber fracture.

Friction and Wear Properties of Carbon Fiber Reinforced PEEK Composites under Water Lubrication

The present study establishes the relationships between the carbon fibers (CF) content and the trbological properties of Polyether ether ketone (PEEK) composite. PEEK composites such as unreinforced PEEK, reinforced PEEK with different content of carbon fibres were used for the tribological tests. The results indicated that CF/PEEK composite had better tribological properties than pure PEEK. Some CF was ground and squeezed, then mixed with debris on the worn surface, which improved the wear resistance greatly. The low friction coefficient of CF/PEEK composite caused little change in the temperature and further ensured the stable state of sliding.

Erosive Wear Studies of Glass fiber- and Carbon Fiber-reinforced Polyetheretherketone Composites at Low Particle Speed

In this study, solid particle erosive wear behavior of randomly oriented short glass fiber and carbon fiber-reinforced polyetheretherketone (PEEK) composites was investigated. The solid particle erosion experiments were carried out at six different contact angles (15—90°) and at low particle speed using brown fused aluminum oxide (Al2O3) particles (500—710 µm) as an erodent. The PEEK composites showed semi-ductile erosion behavior, with a maximum wear amount at a contact angle of 45°. The fiber type and the contact angle had a significant influence on erosion behavior. Glass fiber-reinforced PEEK composites showed better erosive wear resistance than carbon fibre-reinforced composites. Scanning electron microscopy studies were conducted to understand the wear mechanisms involved during the erosive wear.

The Addition of Carbon Nanotube on the Tensile Properties of Carbon Fiber-Reinforced PEEK Composites

The main objective of this paper is to develop high strength resistance carbon fiber-reinforced polyether ether ketone (PEEK) composites with the addition of multiwall carbon nanotubes (MWCNT). These compounds were well mixed in a Haake batch mixer, and compounded polymers were fabricated into sheets of known thickness by compression moulding. Samples were tested for tensile properties with respect to different concentration of fillers. The tensile properties of these samples depend on filler aspect ratio. The tensile fracture surface has been examined using a scanning electron microscope (SEM). Photomicrographs of the worn surfaces revealed the effect of the addition of carbon nanotubes. Also, better interfacial adhesion between carbon and vinyl ester in carbon reinforced vinyl ester composite was observed.

Thermal and Mechanical Properties of PAN- and Pitch-Based Carbon Fiber Reinforced PEEK Composites

Thermal and mechanical properties of different short carbon fibers (CF) reinforced polyether-ether-ketone (PEEK) composites are investigated, where CF is made from polyacrylonitrile (PAN-CF) and pitch (Pitch-CF). The thermal properties of both composites are studied using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The crystallinity of PEEK increases with the content of PAN-CF, but it is independent of Pitch-CF content. At the isothermal condition, the crystallite rate of Pitch-CF/PEEK composite is faster than that of PAN-CF/PEEK composites. Dynamic tensile modulus of PAN-CF/PEEK increases with the CF content. An increase of glass transverse temperature with an increase in CF content is found in PAN-CF/PEEK, but not in Pitch-CF/PEEK. The fracture toughness of PAN-CF/PEEK composites increases with CF contents; whereas it remains the same value for Pitch-CF composite. The fracture surface of both composites is analysed using scanning electron microscopy.