Polyetheretherketone Research Articles

The Development of a 3D-Printed Compliant System for the Orientation of Payloads on Small Satellites: Material Characterization and Finite Element Analysis of 3D-Printed Polyetherketoneketone (PEKK)

This article focuses on the development of a 3D-printed 2-degree-of-freedom (DOF) joint for the payloads’ orientation on small satellites. This system is a compliant mechanism, meaning that this monolithic system composed of cross-axis flexural pivots (CAFPs) produces complex movements through the elastic deformation of its structure. Using fused filament fabrication (FFF), a demonstrator made of Polyetherketoneketone (PEKK) is printed to determine its potential compatibility with space conditions. Focusing on a segment of the joint, the CAFP, this study aims for an enhancement of its mechanical behavior through the study of its printing direction and the creation of an accurate finite element model of this compliant mechanism. First, material characterization of 3D-printed PEKK is achieved through differential scanning calorimetry tests of the filament and flexural and tensile tests of specimens printed in different printing directions. Then, these data are used to perform a finite element analysis of different CAFP designs and compare their mechanical response of their 3D-printed twin using digital image correlation software. Finally, the CAFP structures were observed by X-ray tomography. The results show that printing direction greatly influences both flexural and tensile strength. Voids induced by the FFF process could impact the mechanical behavior of 3D-printed parts as the simple CAFP design has a better test/model correlation than complex ones. This could influence its resistance to space environment.

Optimization and tribological performance of PEEK based composite coatings reinforced with PTFE for friction pairs of aviation hydraulic pumps

In this study, polyetheretherketone (PEEK) based composite coatings reinforced with polytetrafluoroethylene (PTFE) were applied to copper-steel bimetallic plates. The impact of process parameters on the tribological properties of the coatings was investigated. The results indicated that the optimized PTFE/PEEK2.2 coating exhibited commendable friction reduction and wear resistance performance when subjected to aviation kerosene lubrication. It was observed that the hot-pressing temperature has the most significant influence on the bearing capacity and wear rate of the coatings. In contrast, the hot-pressing pressure primarily affects the average friction coefficient. The primary wear mechanism observed in these coatings is adhesive wear. These findings suggest promising application prospects for the composite coatings in aviation hydraulic pumps, underscoring their potential to significantly improve overall performance.

Protecting Orthopaedic Implants from Infection: Antimicrobial Peptide Mel4 Is Non-Toxic to Bone Cells and Reduces Bacterial Colonisation When Bound to Plasma Ion-Implanted 3D-Printed PAEK Polymers.

Even with the best infection control protocols in place, the risk of a hospital-acquired infection of the surface of an implanted device remains significant. A bacterial biofilm can form and has the potential to escape the host immune system and develop resistance to conventional antibiotics, ultimately causing the implant to fail, seriously impacting patient well-being. Here, we demonstrate a 4 log reduction in the infection rate by the common pathogen S. aureus of 3D-printed polyaryl ether ketone (PAEK) polymeric surfaces by covalently binding the antimicrobial peptide Mel4 to the surface using plasma immersion ion implantation (PIII) treatment. The surfaces with added texture created by 3D-printed processes such as fused deposition-modelled polyether ether ketone (PEEK) and selective laser-sintered polyether ketone (PEK) can be equally well protected as conventionally manufactured materials. Unbound Mel4 in solution at relevant concentrations is non-cytotoxic to osteoblastic cell line Saos-2. Mel4 in combination with PIII aids Saos-2 cells to attach to the surface, increasing the adhesion by 88% compared to untreated materials without Mel4. A reduction in mineralisation on the Mel4-containing surfaces relative to surfaces without peptide was found, attributed to the acellular portion of mineral deposition.

A multiscale scheme for homogenization to characterize the flexural performances of injection molded short glass fiber reinforced polyether ether ketone composites

AbstractThe characterization of the flexural performances of short glass fiber reinforced polyether‐ether‐ketone (SGFR‐PEEK) composites fabricated by injection molding is a crucial and challenging task due to the process‐induced fiber orientation at different locations, resulting layered shell‐core‐shell microstructures and exhibiting large variations in mechanical performances. This article proposes a method for predicting the bending performance of SGFR‐PEEK and indicates the influence of fiber orientation on its bending behavior. This article reports a new scheme that combines multiscale homogenization with periodic microstructures and presents an experimental investigation of the flexural properties of SGFR‐PEEK composites. The distributions of fiber orientation through the thickness extracted from the micro‐computed tomography (μCT) were analyzed and reproduced with a layered skin‐shell‐core structure along the thickness at meso‐scale finite element model within representative volume elements (RVEs) of the macroscopic composites. Then, the effective properties of the RVEs were predicted using the homogenization method with the periodic boundary condition. The elastic modulus of skin‐shell‐core layers in the direction of flow are 4260.51, 4541.27, 4628.52, and 4630.84 MPa, respectively. The classical laminate theory (CLT) and the second homogenization implementation were then utilized in conjunction with the obtained mechanical properties of RVEs to predict the effective macrostructural behavior. The flexural modulus of the composite material was determined to be 5448.7 MPa through a three‐point bending test. The results obtained through lamination plate reinforcement theory and finite element simulation were 5887.4 and 5785.9 MPa, respectively, showing good agreement with the experimental findings. It is shown that the proposed multiscale scheme yields satisfactory agreement with experimental measurements. In addition, the effect of layered skin‐shell‐core microstructures on the flexural behavior was discussed.Highlights RVEs of layered shell‐core‐shell microstructures were generated with specified fiber orientations. The homogenization scheme with the periodic boundary condition was adopted to accurately predict each layer mechanical properties. The proposed multiscale scheme was compared with experimental results and yielded satisfactory predictions. The effect of layered skin‐shell‐core microstructures on the flexural behavior was thoroughly studied by the multiscale analytical approach.

Rational Design Toward Advanced Non-Flow Aqueous Zinc-Bromine Systems Boosted by Alkaline-Neutral Decoupling Electrolytes.

Non-flow aqueous zinc-bromine batteries (AZBBs) are highly attractive owing to their lightweight construction and largely reduced cost compared with the flow ones. Yet, their development is restricted by the sluggish reaction kinetics of Br2/Br-, the shuttle of soluble polybromide species (Brn -, n is odd), and the poor stability of Zn-based anode. Herein, an effective alkaline-neutral electrolyte decoupling system is constructed to mitigate these issues, where nitrogen-doped carbon felt with high catalytic activity to Br2/Br- reaction is developed for cathode, a cost-effective cation exchange membrane (CEM) of polyethersulfone/sulfonated polyether ether ketone (PES/SPEEK-M) that can stop Brn - is used as separator, and glucose that can inhibit dendrites is introduced as anolyte additive. The constructed flowless AZBB mainly consists of two separate redox couples, including Zn/Zn(OH)4 2- in alkaline anolyte and Br2/Br- in neutral media, where non-cations(e.g. OH-, Zn(OH)4 2-, H2O, and Brn -) can be restricted to their respective chamber by the PES/SPEEK-M while cations can pass by. In the optimized system, good electrochemical performance is achieved, mainly including a surprising discharge voltage of 2.01V, a high average Coulombic efficiency of 96.7%, and a good cycling life of ≈1000 cycles without obvious capacity decay at a fixed charge capacity of 2mAhcm-2.

Evaluation of High-Performance Polyether Ether Ketone Polymer Treated with Piranha Solution and Epigallocatechin-3-Gallate Coating.

Dental implantation has become a standard procedure with high success rates, relying on achieving osseointegration between the implant surface and surrounding bone tissue. Polyether ether ketone (PEEK) is a promising alternative to traditional dental implant materials like titanium, but its osseointegration capabilities are limited due to its hydrophobic nature and reduced surface roughness. The aim of the study is to increase the surface roughness and hydrophilicity of PEEK by treating the surface with piranha solution and then coating the surface with epigallocatechin-3-gallate (EGCG) by electrospraying technique. The study includes four groups intended to investigate the effect of piranha treatment and EGCG coating: a control group of PEEK discs with no treatment (C), PEEK samples treated with piranha solution (P), a group of PEEK samples coated with EGCG (E), and a group of PEEK samples treated with piranha solution and coated with EGCG (PE). Surface roughness, wettability, and microhardness were assessed through statistical analysis. Piranha treatment increased surface roughness, while EGCG coating moderated it, resulting in an intermediate roughness in the PE group. EGCG significantly improved wettability, as indicated by the reduced contact angle. Microhardness increased by about 20% in EGCG-coated groups compared to noncoated groups. Statistical analysis confirmed significant differences between groups in all tests. This study demonstrates the potential of EGCG coating to enhance the surface properties of PEEK as dental implants. The combined piranha and EGCG modification approach shows promise for improved osseointegration, although further vivo research is necessary. Surface modification techniques hold the key to optimizing biomaterial performance, bridging the gap between laboratory findings and clinical implementation in dental implantology.

Overcoming the Trade-Off between Methanol Rejection and Proton Conductivity via Facile Synthesis of Crosslinked Sulfonated PEEK Proton Exchange Membranes

In this work, homogeneous, thin-film proton exchange membranes (PEMs) with superior proton conductivities and high methanol rejection were fabricated via a facile synthesis procedure. Sulfonated polyether ether ketone (sPEEK) was crosslinked via a Friedel–Crafts reaction by α,α′-dichloro-p-xylene, a non-hazardous and hydrophobic compound. PEMs with varying crosslinking and sulfonation degrees were fabricated to overcome the traditional trade-off between methanol rejection and proton conductivity. The sulfonation of PEEK at 60 °C for 24 h resulted in a sulfonation degree of 56%. Those highly sulfonated backbones, in combination with a low membrane thickness (ca. 20 µm), resulted in proton conductivities superior to Nafion 117. Furthermore, X-ray photoelectron spectroscopy proved it was possible to control the crosslinking degree via the crosslinking time and temperature. The PEMs with the highest crosslinking degree showed better methanol rejection compared to the commercial benchmark. The introduction of the crosslinker created hydrophobic membrane sections, which reduced the water and methanol uptake. Subsequently, the membrane became denser due to the crosslinking, hindering the solute permeation. Those two effects led to lower methanol crossovers. This study proved the successful fabrication of PEMs overcoming the trade-off between proton conductivity and methanol rejection, following a facile procedure using low-cost and non-hazardous materials.

Tribological Behavior of Sulfonated Polyether Ether Ketone with Three Different Chemical Structures under Water Lubrication.

With the development of the shipbuilding industry, it is necessary to improve tribological properties of polyether ether ketone (PEEK) as a water-lubricated bearing material. In this study, the sulfonated PEEK (SPEEK) with three distinct chemical structures was synthesized through direct sulfonated polymerization, and high fault tolerance and a controllable sulfonation degree ensured the batch stability. The tribological and mechanical properties of SPEEK with varying side groups (methyl and tert-butyl) and rigid segments (biphenyl) were compared after sintering in a vacuum furnace. Compared to the as-made PEEK, as the highly electronegative sulfonic acid group enhanced the hydration lubrication, the friction coefficient and wear rate of SPEEK were significantly reduced by 30% and 50% at least without affecting the mechanical properties. And lower steric hindrance and entanglement between molecular chains were proposed to be partially responsible for the lowest friction behavior of SPEEK with methyl side groups, making it a promising and competitive option for water-lubricated bearings.

Bone Mimetic Polyetheretherketone Implant Coating Facilitates Early Osseointegration

AbstractAging society demands advanced bone implants that can achieve long‐term success through osseointegration at the bone‐implant interface. Polyetheretherketone (PEEK), a bioinert implant material, often struggles with connecting to existing bone tissue, leading to inflammation and implant replacement. Following nature's lessons, a new strategy is introduced that masks the surface of bio‐ and chemically inert Polyetheretherketone implants with a covalently anchored bone‐mimetic surface. This method transforms PEEK into a bone‐integrative material by grafting a ≈300 nm thick gelatin layer onto its surface, subsequently mineralized with calcium phosphate. Herein, it is showed that this surface modification for implant materials combines excellent bulk implant properties with the characteristic structure and functional properties of natural bone. In vitro biocompatibility assays, employing NIH‐3T3 fibroblast and MC3T3‐E1 osteoblast cell lines, confirm the enhanced biocompatibility of the modified material. This strategy offers promising prospects for improving bone implants and exemplifies the adaptation of a non‐osseointegrative material to a bone‐like interface.

Allergic reaction of poly-ether-ether-ketone versus titanium implants: A posttest-only control group design experimental study using a rabbit model.

The aim of this study was to determine clinically and genetically the allergic effects of titanium and poly-ether-ether-ketone (PEEK) implants following loading in rabbit tibias. This study included 18 white New Zealand male rabbits (n = 18) divided evenly into three groups: control, titanium (Ti), and PEEK (P). Clinically, the allergenic effect of titanium and PEEK was investigated by detecting the effect on lymph nodes. Furthermore, RT-PCR and ELISA were used to detect the expression of certain genes IL-6, TNF-α, OPG, RANKL, and RUNX-2 through both types of implants. Our findings demonstrated that titanium implants induced enlarged lymph nodes, which PEEK did not. Overall, RT-PCR and ELISA techniques revealed that Ti implants had higher expression of the inflammatory genes IL-6 and TNF-α. Ti had the highest expression in OPG findings, while PEEK had the lowest. RANKL expression was highest in the control group and lowest in the PEEK group. RUNX-2 is the highest for the control group and the lowest for the titanium group. Although titanium implants elicited greater allergy responses than PEEK implants, titanium has the highest expression of bone formation genes and the lowest expression of bone resorption genes, making it preferable to PEEK.

Heat-assisted friction stir incremental sheet forming of thermoplastics

Incremental sheet forming (ISF) has been attracting increasing interests for customised manufacture of thermoplastics, but the application in high-performance and hard-to-form thermoplastics is still a challenge. This paper develops a new heat-assisted friction stir incremental sheet forming (HAFS-ISF) process to form polyether ether ketone (PEEK) and polymethyl methacrylate (PMMA, acrylic). Flexible heating tapes and tool rotational friction heat the thermoplastic sheet on both bottom and top surfaces, which maintain the sheet material at high temperature and reduce the through-thickness temperature gradient. Results are given for the effect of key parameters on forming temperature, force, accuracy and thickness distribution. Spindle speed has the most significant effect on all the studied aspects, followed by the pre-heating temperature, while feed rate and step size have less effect. With lower spindle speed of 100 rpm, the through-thickness temperature gradient is improved. Compared with PEEK parts, more uniform forming temperature and smaller forming force can be observed for PMMA parts. But the material brittleness causes worse formability, and the severer twist and stretching effect affect the forming accuracy of PMMA parts. Forming accuracy, fracture and twist are discussed by developing analytical models. The model for forming accuracy considers the initial bending effect and springback. The fracture is discussed by modelling the stress triaxiality and equivalent strain distribution under contact. While the model for twist considers effect of the applied torque on shear strain energy and continuous accumulation of twist along the tool path. By comparing analytical models and testing observations, the effectiveness of the models is confirmed to understand the underlaying mechanisms and to address a few challenges.

The influence of the machining strategy on milling of polyetheretherketone (PEEK)

The influence of the machining strategy on milling of polyetheretherketone (PEEK)

The quality of life after Anterior Cervical Discectomy and Fusion

Cervical discopathy is commonly associated with pain in the cervical spine which may affect patients’ quality of life. If conservative treatment fails to relieve the pain for at least 6 months and/or if neurological deficit progresses, the surgical treatment is taken under consideration. The aim of this study was to evaluate health-related quality of life (HRQOL) and disability of patients after single- and multi-level anterior cervical discectomy and fusion (ACDF) with standalone polyetheretherketone (PEEK) cages. The study evaluated how ACDF influenced particular aspects of patients’ quality of life in the context of radiological outcome. The study included 30 consecutive patients with single- or multi-level cervical disc herniation. Patients underwent clinical and radiological evaluation before and one year after the ACDF procedure. For each patient, we assessed the severity of cervical pain with a numerical rating scale (NRS) and filled the neck disability index questionnaire (NDI). The health-related quality of life was assessed with the Polish version of 36-Item Short Form Survey (SF-36). A significant decrease in all NDI aspects indicates a significant improvement after surgery. The quality of life in all aspects assessed with SF-36 scale was also improved. A moderate decrease in cervical spine mobility coexisted with a good outcome of the neurosurgical procedure. In the opinion of patients, the most important aspect after the cervical spine surgery is the reduction of pain severity. ACDF surgery is an effective method to reduce the severity of pain in patients with degenerative disc disease. ACDF improves the quality of patient’s life. According to the study results the physical role improved most significantly; the least improvement was noted in role-emotional aspect. Up to 83% of patients achieved a reduction of the NDI index by 5 or more points after surgical treatment which proves the high effectiveness of the surgical treatment. No statistically significant difference was noted between patients with single and multi – level discopathy. Up to 97% of patients who underwent ACDF reported a significant decrease in pain severity measured with NRS.

Mechanical characterization of PEEK-CF/PEEK sandwich structures prepared via a combination of fused filament fabrication and epoxy post-bonding

Poly-ether-ether-ketone (PEEK) and carbon-fiber-reinforced PEEK (PEEK-CF) are examples of engineering thermoplastics with exceptional mechanical properties. In the context of Fused Filament Fabrication (FFF), the interlayer bonding between PEEK and PEEK-CF has a significant impact on the mechanical properties of printed components. Epoxy resin is used to enhance the interfacial bonding between PEEK and PEEK-CF due to its remarkable adhesive properties, while preserving the dimensional and weight attributes of the bonded sandwich structure. The application of epoxy resin as a post-processing technique enables the creation of intricate geometric designs within the bonded sandwich structures. This study presents a straightforward technique for producing sandwich structures using PEEK and PEEK-CF, followed by improving their mechanical properties through isothermal annealing. We conduct systematic single-factor experiments to explore the mechanical advantages of FFF-printed PEEK and PEEK-CF via three-point bending tests on individually printed monolithic specimens. Furthermore, mono-material specimens are bonded using epoxy resin to form dual-material bending specimens. Our findings reveal an optimal sequence: after isothermal annealing, mono-material specimens bonded with epoxy resin exhibit superior flexural strength and modulus. In addition, an in-depth examination of the meso-structure and fracture morphology of FFF-printed sandwich structures after bonding and heat treatment reveals insights into toughening and reinforcement mechanisms. This analysis is complemented by corresponding finite element simulations to validate the results. Notably, our research highlights the successful optimization of interlayer structures, facilitating the creation of sandwich structures with superior mechanical performance.

Polymer composite coatings subjected to sliding wear under simulated lunar temperature and dust conditions

Due to the detrimental effect of lunar dust on tribological components, it is imperative to develop bearing materials and surfaces which can survive and mitigate dust at the interface while operating under lunar environmental conditions. This issue is poised to become more significant in the near future, with lunar exploration evolving beyond the short probing missions of the Apollo era. Therefore, this study aims to investigate the combined effect of temperature and lunar dust on the tribological performance of aromatic thermosetting copolyester (ATSP) and polyether ether ketone (PEEK) -based polymer composite coatings from −150 to 110 °C. The experiments were conducted using a flat pin-on-disk configuration under dry sliding conditions, sliding speed of 0.25 m/s, 17.5 MPa contact pressure, and nitrogen gas environment. It was found that metal-on-polymer coating sliding results in dust embedment and accumulation on the softer material, which yields high friction and two-body abrasive wear. The chemical analysis of transfer film on the metal pin surface indicated a mixture of dust and polymer phases, which increased with increasing temperature, and thus resulted in deteriorated tribological performance. Self-mating polymer coatings yielded lower friction coefficient and wear due to a better dust mitigation resulting in three-body wear at the interface. The ATSP-based coatings showed higher wear resistance at all temperatures, particularly under self-mating sliding condition.

Osteoblast cell behavior on polyetheretherketone dental implant surfaces treated with different grit size aluminum oxide particles: An in vitro analysis

The hydrophobic and bioinert nature of polyetheretherketone (PEEK) implants needs to be addressed for successful osseointegration. The purpose of this in vitro study was to evaluate the osteoblast cell behavior on PEEK implant surfaces treated with airborne-particle abrasion using different grit size aluminum oxide (Al2O3) particles. Disk-shaped specimens (n=96) were prepared from medical grade PEEK rods and were distributed into 4 groups (n=24) of untreated PEEK (PEEK 0), airborne-particle abrasion using 50-μm Al2O3 particles (PEEK 50), airborne-particle abrasion using 110-μm Al2O3 particles (PEEK 110), and airborne-particle abrasion using 150-μm Al2O3 particles (PEEK 150). The surface characteristics were assessed using water contact angle (WCA) measurements and scanning electron microscopy (SEM). MG-63 osteoblast cells were cultured, and the biocompatibility of PEEK was assessed using a CellTiter-blue cell viability assay and florescence staining at day 1, 3, and 7. The specimens were stained with Alizarin red to assess the osteoblast cell differentiation on day 10 and 14. The Levene test was used to test the homogeneity of variances. One-way and Welch ANOVA with post hoc corrections were used to assess the overall statistical significance of differences among the groups (α=.05). The lowest mean WCA was demonstrated in PEEK 150 (49.25 ±5.51) and the highest in PEEK 0 (89.14 ±4.24) (P<.001). SEM images of PEEK 150 illustrated a more complex structure with a large area of globular outcroppings throughout the surface. PEEK 150 showed the highest cell metabolic activity at each time point with florescence staining showing a substantial cell confluence at day 3 and 7. Although PEEK 150 did not show a significant increase in cell proliferation, the number of cells attached was significantly higher than other groups (P<.05). PEEK 110 and 150 also showed a substantial increase in the extent of mineralization. Airborne-particle abrasion using moderate Al2O3 grit size (110- or 150-μm) improved the hydrophilicity and osteoblast cell behavior on PEEK implants.

Stereomicroscope-Based in Vitro Study Evaluating the Marginal and Internal Fit of PEEK and PEKK Crowns.

The aim of the in vitro study was to compare the internal merge and marginal perfection of polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) crowns under a stereomicroscope. All-ceramic preparation is done on the maxillary first premolar which is mounted on the wax block which was scanned using 3Shape scanner and duplicated into 30 acrylic CAD/CAM dies (n = 15) for the placement of PEEK and PEKK crowns. The YENADENT milling system was used to fabricate 15 samples from Group A PEEK crowns and to fabricate 15 samples from Group B PEKK crowns. According to the manufacturer's instructions, an equal amount of the dual-cure resin luting agent (Rely X U200 Self-Adhesive resin, 3M, Germany) was dispensed on the mixing pad before being mixed with cement and painted on the internal surfaces of the copings with the finger pressure crowns which were luted. The values were then analyzed using one-way ANOVA (post hoc) followed by Dunnett's t-test. Among those two groups, PEEK group materials showed the lowest mean value of (28.73.3 ± 4.01) for marginal fit and (26.72 ± 2.53) for internal gap, whereas PEKK group showed a mean value of (32.85 ± 4.63) and (33.06 ± 4.14), respectively. Among these two groups, comparatively less marginal fit and internal adaptation is seen in PEKK when compared to the PEEK crowns. While the marginal fit and internal adaptation of both PEEK and PEKK copings were in acceptable clinical range.

Feasibility analysis of wireless power delivery to implanted sensors of XLIF patients

Abstract The paper aims to aid in developing a monitoring system for surgery patients who have undergone lumbar interbody fusion (LIF). The present body of work functions as a comprehensive analysis of relevant available literature along with our investigation regarding techniques for power delivery; both energy harvesting and wireless power transfer (WPT) alike. In addition, biological considerations are taken into account as they strongly influence the design and testing methodology of an implanted medical device (IMD). This study proposes using inductive coupling as a power delivery method. This was chosen due to the robust nature of the technology, with the IMD being deeply situated and encased in bone and tissue. Three types of receiver coil architectures were explored and designed around the geometry of a polyether ether ketone (PEEK) Extreme lateral interbody fusion (XLIF) Nuvasive Coroent XL interbody cage. With the use of off-the-shelf components, functionality was only attainable for the V3 coil design featured with 0.4 mm wire windings around horizontal and vertical beams present on the implant. The secondary coil was resonantly tuned and optimized for a 141 kHz working frequency. At a 100 mm coupling distance, it was demonstrated that a power delivery load (PDL) of 3.94 mA was able to be induced resulting in a power output of 7.21 mW. The recorded PDLs are capable of powering a high pressure P122 sensor, EFM8BB52 microcontroller, and Ultra-wideband (UWB) data telemetry link, and demonstrate the feasibility of this WPT technique for in vivo monitoring of bone fusion post XLIF surgery.

Variable orientation in material extrusion of short carbon fiber reinforced polymer composites with high thermal conductivity

Controllable orientation architecture possesses tunable thermal behavior for effective heat dissipation in unidirectional product fields, meanwhile without interference with adjacent components. Herein, we proposed a variable orientation strategy in material extrusion of short carbon fiber (SCF) reinforced polymer composites framework with spatially tunable thermal properties. It was achieved due to the following reasons: (Ⅰ) Inherent shear flow in the nozzle; (Ⅱ) Increasing tensile flow by changing the ratio between the printing speed of monofilament and the feeding speed of filament (Vp/f); (Ⅲ) Further surface tension due to thinning monofilament by varying Vp/f. The SCF with different orientations and content reinforced polyether-ether-ketone (PEEK) composites were successfully fabricated. The microcosmic orientation of SCF could be programmed from a three-layer hierarchical framework to a single-layer oriented framework at different Vp/f. Benefit from variable orientation, the through-plane thermal conductivity of SCF/PEEK composites achieved a thermal conductivity enhancement of 173.9 %. In addition, the simulated application of SCF/PEEK composites in the CPU of the computer showed excellent heat transfer during heating. Further, the thermal conductivity mechanism of the synergistic influence between Vp/f and SCF content was analyzed by cross-sectional microstructure. The proposed strategy in this work for fabricating variable orientation of SCF reinforced polymer composites showcases great application prospects in electronic devices and unidirectional product fields.

Analyzing results of cervical sagittal parameters in patients operated with polyetheretherketone cages without plate.

This was a retrospective longitudinal observational study. The purpose of this study was to analyze the results of cervical sagittal parameters on preoperative and postoperative lateral radiographs in anterior cervical discectomy and fusion (ACDF). ACDF is believed to change craniocervical parameters and thus cervical curvature using polyetheretherketone (PEEK) or titanium cages with or without self-locking as well as an anterior plate, the latter of which has not been shown to provide better clinical or radiological results. Cervical spondylotic myelopathy (CSM) is a common degenerative pathology that can affect one or more levels and treatment has varied over time trying to maintain sagittal parameters within acceptable values where the ACDF is the main treatment. The study was performed in patients with CSM who underwent anterior cervical discectomy, and their pre- and postoperative radiographs were analyzed using Surgimap software a few days before and 3 months after surgery. Fifteen files were included in the study. Statistically significant sagittal balance variables were observed in cervical lordosis (CL) with an increase of 4.73° (P = 0.019) and T1 slope (T1S)-CL with a decrease of -5.93° (P = 0.007). CL and T1S-CL showed favorably modified values when performing ACDF using stand-alone PEEK cages without the need for self-blocking or an anterior plate.