Pure Polyetheretherketone Research Articles

Significant tribological enhancement and mechanical property maintenance in PEEK matrix composites with minimal UHMWPE incorporation

Polyether ether ketone (PEEK) is known for its exceptional mechanical properties but has relatively insufficient tribological characteristics. This study seeks to enhance its tribological performance without compromising mechanical properties by fabricating PEEK composites incorporating minimal UHMWPE from 1.0% to 10.0% using hot molding. The hardness, compressive strength, and dry reciprocating friction against bearing steel were evaluated. Results revealed that incorporating just 2.0% UHMWPE into the PEEK matrix significantly reduced the friction coefficient, wear rate, and worn surface roughness by 61%, 89%, and 74%, respectively, compared to pure PEEK, while achieving a notably smooth worn surface. The 2.0% UHMWPE-reinforced PEEK exhibited excellent hardness and compressive strength comparable to pure PEEK, but higher UHMWPE contents decreased these mechanical properties. The UHMWPE proportion of 10.0% resulted in severe adhesive wear, including distinct spalling, plastic deformation, and material accumulation.

3D-Printed high performance PEEK/CF-PEEK polymer composites—An investigation on microstructural characteristics and mechanical performance

This study investigates the microstructural characteristics and mechanical properties of 3D-printed polyether ether ketone (PEEK) and carbon fiber-reinforced PEEK (PEEK CF20) composites. Using a specifically optimized 3D printing process parametric condition, samples of pure PEEK and PEEK CF20 (containing 20% carbon fiber) were fabricated. Mechanical properties were estimated by tensile, flexural, and interlaminar shear strength (ILSS) tests, performed as per ISO and DIN standards. Results indicated that PEEK CF20 exhibits significantly enhanced mechanical properties compared to pure PEEK. The tensile strength of PEEK CF20 was 81.069 MPa, compared to 76.070 MPa for pure PEEK. Maximum load values were 1456.608 N for PEEK CF20 and 1286.137 N for pure PEEK, while ILSS values were 15.76 MPa for PEEK CF20 and 11.82 MPa for pure PEEK. Microstructural analysis through field emission scanning electron microscopy (FESEM) revealed that PEEK CF20 had better fiber-matrix bonding and fewer defects compared to pure PEEK.

Electrically conductive functionalization of cured polyether ether ketone with improved bioactivity by surface-polymerization of polyaniline

The electrically conductive polyether ether ketone (PEEK) holds great promise for antibacterial and cell growth promotion under electrical stimulation, making it a promising material for next-generation implants. However, it is a significant challenge for electrically conductive functionalization of PEEK, especially for cured or shaped PEEK. In addition, PEEK’s bioactivity is still underdeveloped at present. Here, an electrically conductive PEEK with improved bioactivity is prepared through surface-polymerization of polyaniline (PANI) in the shell layer of cured PEEK. Impressively, an extremely high conductivity of 5.2 × 10−2 S/cm is achieved for the conductive PEEK among all the reported PANI/PEEK composites or blends with the optimal conductivity of 3.0 × 10−4 S/cm. It has been demonstrated that the conductive shell layer of the conductive PEEK features a PANI/PEEK semi-interpenetrating polymer network structure, explaining its conductivity. Improved cell proliferative activity is also disclosed for the conductive PEEK compared to that of the pure PEEK, and good biocompatibility and osteogenesis properties are further confirmed for the fabricated conductive PEEK scaffold. This conductive functionalization approach offers a significant advancement for developing next-generation biological implants and could be applied to other cured polymers as well.

3D-printed porous polyether-ether-ketone composite scaffolds for better osteogenic activity

Due to excellent biocompatibility and favorable mechanical properties, polyether-ether-ketone (PEEK) scaffolds are becoming the next-generational orthopaedic implants, but the bioinertness limits their application. In this study, to improve the osteogenic activity of PEEK scaffolds, porous composite scaffolds containing PEEK and biphasic calcium phosphate (BCP) were achieved by 3D printing, which exhibited equilateral triangular profile with the porosity of 69.4 ± 6.3 % and elastic modulus of 186.2 ± 10.9 MPa. The EDS mapping images and XPS spectra indicated increased P and Ca elements in PEEK-BCP scaffolds. The results of in vitro and in vivo evaluations demonstrated that the introduction of BCP significantly increased the osteogenic capacity of PEEK scaffolds and the obvious bone ingrowth could be observed. In conclusion, compared with pure PEEK scaffolds, PEEK-BCP scaffolds with better osteogenic activity are more promising in the orthopaedic and craniofacial field.

The ability of SPEEK to promote the proliferation and osteogenic differentiation of BMSCs on PEEK surfaces

To investigate the ability of sulfonated polyetheretherketone (SPEEK) to promote the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and compare the effects of different degrees of sulfonation (DS), SPEEK was made with two different DS. The L-SPEEK group had a lower DS, while the H-SPEEK group had a higher DS. The physicochemical properties of both species were evaluated by scanning electron microscopy (SEM), capitilize Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Then, proliferation and osteogenic differentiation between the two groups and with pure polyetheretherketone (PEEK) were compared after surface inoculation of bone marrow mesenchymal stem cells (BMSCs). Scanning electron microscopy (SEM) revealed that the surface of the PEEK substrates could be smooth or coarse, and the degree of roughness increased with increasing sulfonation. FTIR spectroscopy showed that both the L-SPEEK and H-SPEEK samples contained sulfonic acid. TGA and XRD revealed that the components in the two groups were the same, but the intensities were different. After BMSC inoculation, a CCK8 assay revealed that the cells proliferated more on the H-SPEEK surface and little on the L-SPEEK surface compared with the PEEK surface. Then, osteogenic differentiation was verified by immunofluorescence staining for OCN and Runx2, which indicated that H-SPEEK had the greatest effect on improving differentiation. The results of alizarin red staining (ARS) and alkaline phosphatase staining (APS) also revealed this trend. Sulfonation can change the microsurface of PEEK, which can improve both BMSC proliferation and osteogenic differentiation.

Determination of “tribological performance working fields” for pure PEEK and PEEK composites under dry sliding conditions

Poly-ether-ether-ketone (PEEK) and PEEK composites are widely used polymers in many engineering applications where dry sliding is required. In this study, the influence of sliding velocity and applied load values on the friction and wear behavior of pure PEEK, 30 wt% glass fiber reinforced PEEK (PEEK-30GF), 30 wt% carbon fiber reinforced PEEK (PEEK-30CF) and 10 wt% carbon fiber+10 wt%graphite +10 wt%poly-tetra-fluoro-ethylene (PTFE) filled PEEK (ie. High (H) pressure (P) and velocity (V) resistant PEEK (PEEK-HPV)) composites rubbing against AISI 304 stainless steel disc was investigated. The experiments were carried out at room temperature under dry sliding conditions in a pin-on-disc wear rig. The applied loads ranged from 30 to 250 N, while the sliding velocities ranged from 1.0 to 4.0 m/s. At these load and velocity ranges, the friction coefficient-wear rate relationship of pure PEEK and composites was established and evaluated. In addition, the operating load-velocity limits of each material were determined and stated. The lowest coefficient of friction and wear rate were obtained in PEEK-HPV, PEEK-30CF, PEEK-30GF composites and pure PEEK polymer, respectively. In addition, it was observed that the coefficient of friction (CoF) decreased and the specific wear rate (SWR) increased with the increase in sliding velocity and applied load in all PEEK materials. The wear rate values of PEEK-HPV and PEEK-30%CF composites are in the range of 10−7 - 10−6 (mm3/Nm), while the wear rate values of pure PEEK and PEEK-30%GF are in the range of 10−6 - 10−5 (mm3/Nm). It was determined that carbon fiber, graphite and PTFE additives added to PEEK polymer as hybrid were very effective in reducing the wear rate of PEEK composite (PEEK-HPV). An adhesive wear mechanism was observed in PEEK-HPV and PEEK-30CF composites both at low load and velocity values and at high load and velocity values.

Comparative evaluation on surface nanohardness, surface microhardness, surface roughness, and wettability of plant-based organic nanoparticle reinforced polyetheretherketone as an implant material - An in vitro study.

Synthetic inorganic materials are commonly used as reinforcing agents in polyetheretherketone (PEEK) composite, whereas natural organic plant-based reinforcing agents are negligible. Surface hardness, roughness, and wettability are indicative factors of osseointegration behavior to be used as an implant material. This study evaluated micro surface hardness (MSH), nano surface hardness (NSH), surface roughness (SR), and contact angle (CA) of PEEK-Azadirachta indica reinforced at 10 wt%, 20 wt%, and 30 wt%. This was an in vitro study. Neem (A. indica) leaf nanoparticles were prepared and reinforced with PEEK powder at 10%, 20%, and 30% weight ratios by injection molding. Sixty specimens underwent the microhardness and CA testing using a digital microhardness tester, and CA goniometer, respectively, and later nanoindentation test to analyze the nanohardness and SR. A one-way ANOVA test with a 95% confidence interval for MSH and NSH, SR, and CA was performed on the samples. A post hoc Bonferroni test was conducted (α = 0.05) to compare the groups. There was a significant increase in nanohardness (P = 0.000) with zero difference in microhardness (P = 0.514). The addition of 10 wt%, 20 wt%, and 30 wt% nanoparticles increased the SR value of the pure PEEK from 273.19 nm to 284.10 (3.99%), 296.91 (8.68%), and 287.54 (5.24%), respectively. In the analysis of the CA, CA 20% shows the lowest angle (63.69) with the highest for control specimens (82.39). There is an increase in the PEEK composite SR with a decrease in CA. The addition of plant-derived nanoparticles into the PEEK matrix has a significant impact on the hardness and hydrophobicity enhancing cell growth and osteoblastic differentiation during osseointegration of dental implants.

Improving interfacial and mechanical properties of epoxy resin composites by chemical grafting modification of poly‐ether‐ether‐ketone microparticles with carbon nanotubes

AbstractThe research on epoxy resin toughening is of great significance for its application in aerospace, automotive industries, marine vessels, and other fields. Poly‐ether‐ether‐ketone (PEEK) and carbon nanotubes (CNTs) are ideal candidates for epoxy reinforcement in thermoplastic materials and nanomaterials, respectively. In this study, CNTs were first chemically grafted onto PEEK microparticles using an amidation reaction. These modified hybrid materials were then utilized as fillers in epoxy composites to enhance their strength and toughness. The changes in sample structure, composition, thermal properties, and wettability during the chemical grafting process between CNTs and PEEK were systematically studied. In comparison to pure PEEK, the surface energy of CNTs‐PEEK hybrid materials increased by 11.58% due to CNTs grafting, resulting in improved wettability and enhanced interface bonding between PEEK and the epoxy matrix. Concurrently, the CNTs‐PEEK/epoxy composites exhibited significant enhancements, with the highest tensile strength, tensile elongation at break, flexural strength, and flexural modulus increased by 31.00%, 30.84%, 121.43%, and 23.22%, respectively. The positive reinforcement effect of modified CNTs‐PEEK fillers in epoxy composites and the exploration of CNTs grafting onto PEEK extend the potential applications of epoxy composites.Highlights CNTs were bonded to PEEK via an amidation reaction by the chemical grafting method. CNTs‐PEEK have an 11.58% increase in surface energy compared to pure PEEK. CNTs‐PEEK/epoxy composites showed improved mechanical properties. The enhancement mechanisms of CNTs‐PEEK/epoxy composites were analyzed.

Tribological behavior evaluation of poly-ether-ether-ketone (PEEK) in dry journal bearing on shaft wear test

This paper investigated the tribological behavior of pure PEEK playing as a dry journal bearing, sliding against stainless steel, under real-life operating conditions in a wear test lasting 2 h. Four conditions were carried out with different magnitudes of normal load and sliding speed, while keeping a constant PV parameter. Sample topography assessments were performed with scanning electron microscopy and white light interferometry techniques. In addition, PEEK samples were also evaluated by Fourier Transformed Infrared Spectroscopy and thermal analyses by Differential Scanning Calorimetry. The coefficient of friction (COF) changed throughout the wear test and exhibited a running-in period followed by a transition, with an increase of COF, and then a tendency to reach a steady-state. Moreover, the COF behavior obtained suggests that there was an influence of the wear test parameters, mainly right after the running-in period — and the COF averages for the steady-state period were statistically equal. Stainless steel samples showed mild wear, while PEEK samples had a drastic alteration of their topography imposed by the wear test — including an increase in its degree of crystallinity. Nonetheless, the PEEK journal bearing samples did not fail from wear and their mass losses were small. Polymeric wear particles were generated and were found weakly adhered to both the body and the counter body. PEEK exhibited a lumpy transfer process — nonetheless, SEM images evaluation was useful to verify that these particles were eventually merged during sliding, and kneaded in the convex-concave contact, which provided them a film-like appearance. Furthermore, adhesive and abrasive wear mechanisms were identified, which were shown to be related to the journal bearing on shaft wear test arrangement.

Elucidation of role of carbon fibers on joining of metal to composite

Weight reduction in the various application fields has propelled to the forefront in investigations of combining metal with polymer. Different from other studies, this work focused on exploring the effect of carbon fibers on the thermal joining of metal to composite. Three plastics with different fiber contents including pure polyether-ether-ketone (PEEK), short carbon fibers reinforced PEEK (SCF/PEEK), and continuous reinforced PEEK (CF/PEEK) were chosen to join to the 6061aluminum alloy using a fiber laser. Results showed the thermal transfer was fostered along the carbon fiber orientation due to a higher thermal conductivity, decreasing the heat accumulation at the interface. However, the existence of carbon fibers also hindered the spreading of plastics on the aluminum alloy surface. This led to a smaller adhesion width and lower tensile-shear force of joints. In addition, the tensile-shear strength of joints prepared with carbon fibers was enhanced owing to lower thermal expansion coefficient, which improved the thermal shrinkage and reduced the stress concentration at the interface. Ultimately, the role of carbon fibers during laser joining of aluminum alloy to plastics was explained, clarifying the bonding mechanism of two materials.

Covalently modified graphene and 3D thermally conductive network for PEEK composites with electromagnetic shielding performance

Polyetheretherketone (PEEK) has inferior interfacial compatibility due to its rigid structure. Hence, achieving the desired thermal conductivity (TC) of PEEK composites is challenging. Covalently bonded amino-graphene (NH2-GnPs) and polybenzoxazine (PBZ) can reduce interfacial thermal resistance (ITR). Hybrid NH2-GnPs and multi-walled carbon nanotubes (MWCNTs) were applied synergistically to refine the TC pathways. Additionally, the 3D thermally conductive network was constructed from electrospun NH2-GnPs&MWCNTs/ketimine-biphenyl polyetheretherketone (PEBEKt) and freeze-dried MWCNTs/[email protected] composites arranged in a sandwich structure. The oriented fillers could improve the heat diffusion network by increasing heat flow conveyance. The optimal in-plane and through-plane TC values were 21.0 and 6.9 Wm−1K−1, respectively, 90 and 29 times those of pure PEEK. The composites also exhibited excellent electromagnetic shielding (80.4 dB, 21.1%), thermal stability, and thermal management capabilities. Consequently, the 3D thermally conductive composites can provide a viable idea for thermal management and electromagnetic shielding materials.

Fabrication process optimization of nHA–CNTs-reinforced PEEK hybrid nanocomposite

Compression molding is the leading fabrication process for polymer composites. The settings of process parameters highly influence the mechanical properties of composites. This study optimized the ball-mixing and compression-molding process parameters for the fabrication of hybrid nanocomposites based on polyetheretherketone (PEEK), multiwalled carbon nanotubes (MWCNTs) and nano-hydroxyapatite using the Taguchi method. The elastic modulus examined using the nanoindentation method of static mechanical analysis was taken as the output response variable. The optimum levels of mixing time, mold temperature, mold pressure and holding time process parameters for the maximum elastic modulus were found to be 90 min, 400°C, 150 bar and 15 min, respectively. The analysis of variance technique showed that the mold temperature had the highest contribution (46.82%) in enhancing the elastic modulus to the largest value. The elastic modulus and hardness of the PEEK-based hybrid nanocomposite with 30 wt.% nHA and 3 wt.% MWCNTs were observed to be 83 and 65% higher than those of pure PEEK, respectively. The hydrophilicity of PEEK was improved with the reinforcement of nHA, attributed to the presence of oxygen-containing functional groups in the chemical structure of nHA.

Material Extrusion 3D Printing of PEEK-Based Composites.

High-performance thermoplastics like polyetheretherketone (PEEK), with their outstanding thermal stability, mechanical properties and chemical stability, have great potential for various structural applications. Combining with additive manufacturing methods extends further PEEK usage, e.g., as a mold insert material in polymer melt processing like injection molding. Mold inserts must possess a certain mechanical stability, a low surface roughness as well as a good thermal conductivity for the temperature control during the molding process. With this in mind, the commercially available high-performance thermoplastic PEEK was doped with small amounts of carbon nanotubes (CNT, 6 wt%) and copper particles (10 wt%) targeting enhanced thermomechanical properties and a higher thermal conductivity. The composites were realized by a commercial combined compounder and filament maker for the usage in a material extrusion (MEX)-based 3D-printer following the fused filament fabrication (FFF) principle. Commercial filaments made from PEEK and carbon fiber reinforced PEEK were used as reference systems. The impact of the filler and the MEX printing conditions like printing temperature, printing speed and infill orientation on the PEEK properties were characterized comprehensively by tensile testing, fracture imaging and surface roughness measurements. In addition, the thermal conductivity was determined by the laser-flash method in combination with differential scanning calorimetry and Archimedes density measurement. The addition of fillers did not alter the measured tensile strength in comparison to pure PEEK significantly. The fracture images showed a good printing quality without the MEX-typical voids between and within the deposited layers. Higher printing temperatures caused a reduction of the surface roughness and, in some cases, an enhanced ductile behavior. The thermal conductivity could be increased by the addition of the CNTs. Following the given results, the most critical process step is the compounding procedure, because for a reliable process-parameter-property relationship, a homogeneous particle distribution in the polymer matrix yielding a reliable filament quality is essential.

Impact of recovered silicon particles incorporation on tribo-characteristics of a poly ether ether ketone polymer composite

The tribological behaviour of polyether ether ketone (PEEK) polymer filled with various concentrations of recovered silicon particles (0, 1, 3, 5, and 10 wt%) fabricated by the hot press technique was investigated in this research work. The hardness and wear properties of the prepared composite materials were evaluated through the Shore D hardness and the pin-on-disc methods. The Shore D hardness of the PEEK composite containing 10% silicon was about 95. This was due to the silicon's better dispersion influencing hardness enhancement. The current study found that adding 10% recycled silicon to PEEK decreased the rate of wear to 0.77*10−6 mm3/Nm and the coefficient of friction (COF) to 0.06. PEEK composites are filled with 10% silicon particles. Silicon particles were responsible for elevating wear resistance and anti-friction behaviour compared to pure virgin PEEK. The wear-behaviour of the PEEK/Silicon composite was greatly influenced by the formation of a transfer film, which avoids direct contact between countersurface steel asperities and the composite. The lubricity effect was obtained by incorporating silicon particles in the PEEK matrix as sliding surfaces with a steel counter surface that tend to form iron oxide and passive hydration mixed transfer films, decreasing COF and wear considerably. The tribofilm firmly adheres to the counter disc through the mechanical interlocking of silicon particles, enabling higher tribofilm bond strength.

Strength and bioactivity of PEEK composites containing multiwalled carbon nanotubes and bioactive glass

Polyetheretherketone (PEEK) polymer is a widely accepted implantable biomaterial in the biomedical field. However, PEEK has a low elastic modulus (E-modulus) as well as a bio-inert nature which is not conductive to rapid bone cell attachment, hence, producing delayed or weak bone-implant integration. Multiwalled carbon nanotubes (MWCNTs) represent one of the strongest known materials that could be added to a polymer to improve its mechanical properties. Bioactive glasses (BGs) can form hydroxyapatite deposits on their surfaces and form a tight bond with the bone, thus, their incorporation into the PEEK matrix may improve its bioactivity. MethodsEight groups were formulated according to the type and percentage of modification of PEEK by MWCNTs and BGs. Group 1: Pure PEEK (P), Group 2: P + 3% MWCNTs (PC3), Group 3: P + 5% MWCNTs (PC5), Group 4: P + 5% BGs (PG5), Group 5: P + 10% BGs (PG10), Group 6: P + 3% MWCNTs + 5% BGs (PC3G5), Group 7: P + 3% MWCNTs + 10% BGs (PC3G10), and Group 8: P + 5% MWCNTs + 5% BGs (PC5G5). Characterization of the vacuum-pressed PEEK and PEEK composite specimens was done using FE-SEM, EDS, FT-IR and TF-XRD. Three-point load test was done to obtain the flexural strength (F.S) and the E-modulus of the specimens. Wettability was determined by measuring the contact angle with distilled water. In-vitro bioactivity was determined after immersion of specimens in simulated body fluid (SBF). Moreover, the effect of the specimens on osteoblastic cell viability was evaluated. ResultsThree-point load test results have shown an improvement in both F.S. and E-modulus for groups PC5, PC3G5 and PC5G5. The lowest contact angle was obtained for group PC5G5 followed by the PC3G10 group. All specimens containing BGs showed the formation of hydroxyapatite-like deposits after their immersion in SBF, as well as an improvement in osteoblastic cell viability compared to PEEK. ConclusionPC3G10, PC3G5 and PG10, groups are promising for the fabrication of patient-specific implants that can be used in low-stress-bearing areas.

Effects of ambient humidity and sintering temperature on the tribological and antistatic properties of PEEK and CF/PEEK

Polyether ether ketone (PEEK) is one of the representatives of special engineering plastics. Due to the high molding temperature, the molding method of ordinary plastics and cavity abrasives are difficult to meet the requirements. In view of this, pure PEEK was prepared by vacuum hot pressing sintering technology at different sintering temperatures. The mechanical properties and microstructure characterization results showed that the pure PEEK prepared at 350 °C showed excellent friction and wear properties. Then PEEK and CF/PEEK composites were prepared at the optimum sintering temperature. The friction experiments of prepared materials were carried out using UMT-2. The effects of ambient humidity on the tribological properties, wear mechanism and antistatic properties of prepared materials were systematically studied. The surface analysis and properties of the materials were measured by 3D profiler, scanning electron microscope, friction electrostatic tester. The results showed that friction coefficient of PEEK and CF/PEEK composite changed slightly with increase of ambient humidity. The wear rate of PEEK decreased firstly and then increases, which reached the lowest of 3.09 × 10−5 mm3/Nm when the ambient humidity was 40%. The wear rate of CF/PEEK composite changed slightly, which was significantly lower than that of PEEK, and the main wear mechanism was adhesive wear. The surface friction static electricity of PEEK and CF/PEEK composites decreased with the increase of humidity.

A biomimetic gradient porous cage with a micro-structure for enhancing mechanical properties and accelerating osseointegration in spinal fusion.

Spinal fusion is a widely employed treatment of patients with degenerative disc disease, in which a cage is used to replace the disc for spinal fusion. But it often fails for insufficient mechanical strength and poor osseointegration. Here, we designed a polyether-ether-ketone (PEEK)/tantalum (Ta) composite cage with a biomimetic gradient porous micro-structure, simultaneously enhancing mechanical properties and accelerating osseointegration in spinal fusion. In the study, based on the mechanical performances of PEEK and osteogenic potential of Ta, and the three-dimensional (3D) structures of cuttlebone and vertebra, the cages were respectively 3D printed by pure PEEK, PEEK with 5wt% Ta (PEEK/Ta-5), PEEK with 10wt% Ta (PEEK/Ta-10) and PEEK with 15wt% Ta (PEEK/Ta-15), then verified in vitro and in sheep cervical fusion model systematically. Vertebral Gyroid structure PEEK/Ta-15 cage exhibited superior mechanical properties than Cuttlebone-like structure PEEK/Ta-15 cage, closer to the cervical vertebra. Furthermore, PEEK/Ta-15 cage with higher Ta microparticles in PEEK provided a biomimetic gradient porous micro-structure with higher surface energy, guiding cell biological behavior, promoting new bone penetration, and accelerating osseointegration in vivo. In conclusion, the study designed a biomimetic gradient porous cage with a micro-structure for enhancing mechanical properties, accelerating osseointegration and forming an anatomical lock in the fusion segment through composites, mechanical efficiency, surface extension, and pores.

Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Using Double Cages: Surgical Techniques and Treatment Outcomes.

To describe the surgical techniques and the treatment outcomes of biportal endoscopic transforaminal lumbar interbody fusion (BETLIF) using double cages. This study included 89 patients with 114 fusion segments between July 2019 and May 2021. One pure polyetheretherketone (PEEK) cage and 1 composite titanium-PEEK cage were used for interbody fusion. Clinical outcomes measures included visual analogue scale (VAS) scores for lower back pain and leg pain, Oswestry Disability Index (ODI), and Japanese Orthopedic Association (JOA) scores. Computed tomography (CT) of the lumbar spine 1 year postoperatively was used to evaluate the Bridwell interbody fusion grades. There were significant improvement in VAS for lower back pain from 5.2 ± 3.1 to 1.7 ± 2.1, VAS for leg pain from 6.3 ± 2.5 to 1.7 ± 2.0, ODI from 46.7 ± 17.0 to 12.7 ± 16.1, and JOA score from 15.6 ± 6.3 to 26.4 ± 3.2. The p-values were all < 0.001. The average hospital stay was 5.7 ± 1.1 days. The CT studies available for 60 fusion segments showed successful fusion (Bridwell grade I or grade II) in 56 segments (93.3%). Significant cage subsidence of more than 2 mm was only noted in 3 segments (5.0%). Complications included 1 dural tear, 2 pedicle screws malposition, and 2 epidural hematomas, in which 2 patients required reoperations. BETLIF with double cages provided good neural decompression and a sound environment for interbody fusion with a big cage footprint, a large amount of bone graft, endplate preservation, and segmental stability.

Wear resistant PEEK composites with great mechanical properties and high thermal conductivity synergized with carbon fibers and h‐BN nanosheets

AbstractIt is well known that carbon fiber (CF) reinforced PEEK (polyether‐ether‐ketone) (defined as “PEEK/CF”) composites have excellent properties and have been widely used in diverse fields. Meanwhile, hexagonal boron nitride (h‐BN), as an excellent nano reinforcing agent, is often incorporated into polymer to improve its mechanical strength and thermal conductivity. Herein, PEEK matrix was regulated by adding high‐strength CF as the load‐bearing phase and 2D h‐BN sheets as the solid lubricant and thermally conductive fillers prepared by melt blending to achieve the multi‐scale packing of uniform mixing. The results show that h‐BN is well dispersed in PEEK matrix and improves the interfacial bonding between CF and PEEK matrix, exhibiting a good synergistic effect in enhancing tensile properties of composites. PEEK composite with 20 wt% CF and 4 wt% h‐BN (referred as P/20C/4B) exhibits the highest tensile strength (176.05 MPa) and thermal conductivity (0.396 W/(m·K)), which are 97.54% and 126.3% over those of pure PEEK (89.12 MPa; 0.175 W/(m·K)), respectively. In addition, PEEK composite with 10 wt% CF and 4 wt% h‐BN (referred as P/10C/4B) has excellent tribological properties with a friction coefficient of 0.15, the lowest fiction temperature (30.5°C) and a relative low wear rate of 1.62 × 10−6 mm3/(N·m) among them. The synergitic effects of h‐BN and CF on mechanical, tribological properties and thermal conductivity of PEEK composites provides a very broad prospect in their application of low frictional and wear resistant polymeric materials.

3D-printed polyether-ether-ketone/n-TiO2 composite enhances the cytocompatibility and osteogenic differentiation of MC3T3-E1 cells by downregulating miR-154-5p.

The object was to enhance the bioactivity of pure polyether-ether-ketone (PEEK) by incorporating nano-TiO2 (n-TiO2) and investigate its potential mechanism. PEEK/n-TiO2 composite was manufactured using a 3D PEEK printer and characterized by scanning electron microscopy (SEM), 3D profiler, energy-dispersive spectroscopy, and Fourier-transform infrared (FT-IR) analyses. Cytocompatibility was tested using SEM, fluorescence, and cell counting kit-8 assays. Osteogenic differentiation was evaluated by osteogenic gene and mineralized nodule levels. The expression of the candidate miRNAs were detected in composite group, and its role in osteogenic differentiation was studied. As a results the 3D-printed PEEK/n-TiO2 composite (Φ = 25 mm, H = 2 mm) was successfully fabricated, and the TiO2 nanoparticles were well distributed and retained the nanoscale size of the powder. The Ra value of the composite surface was 2.69 ± 0.29, and Ti accounted for 22.29 ± 12.09% (in weight), and FT-IR analysis confirmed the characteristic peaks of TiO2. The cells in the composite group possessed better proliferation and osteogenic differentiation abilities than those in the PEEK group. miR-154-5p expression was decreased in the composite group, and the inhibition of miR-154-5p significantly enhanced the proliferation and osteogenic differentiation abilities. In conclusion, 3D-printed PEEK/n-TiO2 composite enhanced cytocompatibility and osteogenic induction ability by downregulating miR-154-5p, which provides a promising solution for improving the osteointegration of PEEK.