Search Results (23)

Polyaryletherketone (PAEK) polymers inherently exhibit low surface activity, leading to poor adhesive bonding performance when using epoxy-based adhesives. In this study, low-temperature plasma surface modification was conducted on carbon fiber-reinforced polyetherketone ketone (CF/PEKK) composites to investigate the influence of plasma treatment parameters on their lap shear strength. Surface characterization was systematically performed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and contact angle analysis to evaluate morphological, chemical, and wettability changes induced via plasma treatment. The results demonstrated a significant enhancement in lap shear strength after plasma treatment. Optimal bonding performance was achieved at a treatment speed of 10 mm/s and a nozzle-to-substrate distance of 5 mm, yielding a maximum shear strength of 28.28 MPa, a 238% improvement compared to the untreated control. Notably, the failure mode transitioned from interfacial fracture in the untreated sample to a mixed-mode failure dominated by cohesive failure of the adhesive and substrate. Plasma treatment substantially reduced the contact angle of CF/PEKK, indicating improved surface wettability. SEM micrographs revealed an increased micro-porous texture on the treated surface, which enhanced mechanical interlocking between the composite and adhesive. XPS analysis confirmed compositional alterations, specifically elevated oxygen-containing functional groups on the plasma-treated surface. These modifications facilitated stronger chemical bonding between CF/PEKK and the epoxy resin, thereby validating the efficacy of plasma treatment in optimizing surface chemical activity and adhesion performance. Full article

The aim of this study was to evaluate the influence of filler type, filler content, and filler silanization on the flexural strength (FX), elastic modulus (E_m), shore D hardness (SDH), and two-body wear (2BW) of polyaryletherketone (PAEK) compounds. Specimens (40 wt% PEEK, 40 wt% PEK) with different filler types: 20 wt%: fumed silica (FS), calcium silicate (CS), feldspar (FP), magnesium silicate hydrate (MSH), no filler (NF); different filler content: 20, 25 or 30 wt% CS; different filler silanization: 20 wt% CS silanized with alkylsilane/aminosilane, FP silanized with methylsilane/ vinylsilane, no silanization; and PEEK₂₀ (BioHPP) or PEEK₂₅ (BioHPP plus) controls were fabricated and tested for FX, E_m, and SDH. Two-body wear (4 × 100,000 cycles, 50 N, 2.5 Hz) with composite resin antagonists was measured with PAEK_i (35 wt% PEEK, 35 wt% PEK, 30 wt% CS), PAEK_ii (70 wt% PEEK, 30 wt% CS), PAEK_iii (70 wt% PEEK, 25 wt% CS, 5 wt% FP), and PEEK₂₀ controls. Data were analyzed with Kolmogorov–Smirnov-, Kruskal–Wallis-H-, post hoc Scheffé test, pairwise comparisons, Bonferroni correction, one-way ANOVA, and Spearman rho (α = 0.05). An abrasion area analysis was performed. Adding filler increased FX, E_m, and SDH, with CS and MSH showing the highest values for FX and E_m. Adding 30 wt% CS increased FX, E_m, and SDH compared with 20 wt%. Silanization with methylsilane increased FX, E_m, and SDH. Silanization with aminosilane increased FX and SDH. PEEK₂₀ showed the lowest 2BW compared with all EPCs. No material losses were detected on the antagonists. PAEK compounds with 25 to 30 wt% CS increased FX and E_m compared to lower contents, no filler, or PEEK₂₀. Higher values of FX and E_m did not lead to lower 2BW. Full article

Polyaryletherketone (PAEK) materials, including polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), possess excellent mechanical properties and biocompatibility; however, their inherently low surface energy limits effective bonding with resin cements. This study investigated the effects of hydrofluoric acid (HF) etching and handheld nonthermal plasma (HNP) treatment on enhancing the adhesive performance of PAEK surfaces. Disk-shaped PEEK (BP) and PEKK (PK) specimens were divided into four groups: APA (airborne-particle abrasion), PLA (nonthermal plasma treatment), LHF (5.0% HF), and HHF (9.5% HF). Surface characterization was performed using a thermal field emission scanning electron microscope (FE-SEM). Surface wettability was evaluated using contact angle goniometry. Cytotoxicity was evaluated using HGF-1 cells exposed to conditioned media and analyzed via PrestoBlue assays. Shear bond strength (SBS) was measured after three aging conditions—NT (no aging), TC (thermocycling), and HA (highly accelerated aging)—using a light-curing resin cement. Failure modes were categorized, and statistical analysis was performed using one-way and two-way ANOVA with Tukey’s HSD test (α = 0.05). Different surface treatments did not affect surface characterization. PLA treatment significantly improved surface wettability, resulting in the lowest contact angles among all groups, followed by HF etching (HHF > LHF), while APA showed the poorest hydrophilicity. Across all treatments, PK exhibited better wettability than BP. Cytotoxicity results confirmed that all surface treatments were nontoxic to HGF-1 cells, indicating favorable biocompatibility. SBS testing demonstrated that PLA-treated specimens achieved the highest and most stable bond strength across all aging conditions. Although HF-treated groups exhibited lower bond strength overall, BP samples treated with HF showed relatively less reduction following aging. Failure mode analysis revealed a shift from mixture and cohesive failures in the NT aging condition to predominantly adhesive failures after TC and HA aging conditions. Notably, the PLA-treated groups retained mixture failure patterns even after aging, suggesting improved interfacial durability. Among the tested methods, PLA treatment was the most effective strategy, enhancing surface wettability, bond strength, and aging resistance without compromising biocompatibility. In summary, the PLA demonstrated the greatest clinical potential for improving the adhesive performance of PAEK when used with light-curing resin cements. Full article

Neck and lower back pain, often caused by spinal disorders such as scoliosis and degenerative disc disease, affects over 80% of the global population, with an estimated from 250,000 to 500,000 spinal cord injuries occurring annually according to the WHO. As the demand for spinal procedures continues to rise, advancements in implant materials have become essential. Orthopedic implants play a vital role in restoring mobility and improving the quality of life of patients with musculoskeletal disorders. Metallic implants, such as stainless steel, titanium, and its alloys, are commonly used to make fixation devices for spinal fusion surgery due to their excellent mechanical properties. However, complications such as stress shielding have been recorded. Polymeric materials offer new prospects as an alternative to metal-based materials such as those based on Polyaryletherketone (PEAK). Among the advanced materials used in these implants, PAEK has emerged as the preferred choice due to its exceptional mechanical strength, thermal stability, and chemical resistance. Polyetheretherketone (PEEK) and Polyetherketoneketone (PEKK) offer notable advantages, such as radiolucency and mechanical properties resembling those of natural bone, reducing stress shielding and facilitating postoperative imaging. Although PEEK and PEKK are considered as bioinert, it has been demonstrated that adding bioactive agents such as hydroxyapatite (HA) into the matrix to make composites solves this problem and can help with aiding direct bone apposition. Furthermore, PAEK’s compatibility with 3DP enables the creation of patient-specific implants with intricate geometries, enhancing the surgical outcomes. In addition, the lattice structures of orthopedic implants can alleviate stress shielding, provide an enhanced surface area for the release of bioactive agents (or antimicrobial materials), and eliminate more imaging artifacts compared to that of simple, solid metal implants. PAEK/HA composite implants represent a transformative solution, addressing the psychological, social, and economic burdens of spinal disorders, while enhancing the surgical outcomes. With continuous technological evolution, PAEK/HA composites are poised to play a pivotal role in modern spinal care. Full article

Recent advancements in thermoplastics within the polyaryletherketone (PAEK) family have enhanced additive manufacturing (AM) potential in fields like aerospace and defense. Polyetheretherketone (PEEK), the best-studied PAEK, faces limitations in AM due to its fast crystallization, which causes poor inter-filament bonding and warping. This study investigated alternative, slow-crystallizing PAEK polymers: polyetherketoneketone (PEKK-A) and AM-200, a PEEK-based copolymer. Both can be printed in an amorphous state and then annealed to improve crystallinity and mechanical properties. Despite their potential, these materials have been minimally explored for AM. Our analysis compared the mechanical performance of as-printed and annealed samples and showed that slow-crystallizing PAEKs outperform fast-crystallizing PEEK. As-printed PEKK-A and AM-200 parts reached tensile strengths of 69 MPa and 47 MPa, respectively, which are about 80% of the values for injection-molded parts. In contrast, PEEK achieves only 25% due to poor inter-layer bonding. Annealing increased crystallinity (15.7% for PEKK-A, 19% for AM-200), simultaneously leading to a coalescence of smaller pores into larger ones, which affected mechanical integrity. Annealing strengthened the printed filament direction, while Z-direction strength remained limited by interlayer adhesion. Our work provides new insights into optimizing these relationships to expand the applicability of PAEK in additive manufacturing. Full article

Additive Manufacturing (AM) enables the automated production of complex geometries with low waste and lead time, notably through Material Extrusion (MEX). This study explores Large Format Additive Manufacturing (LFAM) with carbon fiber-reinforced polyaryletherketones (PAEK), particularly a slow crystallizing grade by Victrex. The research investigates how extrusion parameters affect the mechanical properties of the printed parts. Key parameters include line width, layer height, layer time, and extrusion temperature, analyzed through a series of controlled experiments. Thermal history during printing, including cooling rates and substrate temperatures, was monitored using thermocouples and infrared cameras. The crystallization behavior of PAEK was replicated in a Differential Scanning Calorimetry (DSC) setup. Mechanical properties were evaluated using three-point bending tests to analyze the impact of thermal conditions at the deposition interface on interlayer bonding and overall part strength. The study suggests aggregated metrics, enthalpy deposition rate and shear rate under the nozzle, that should be maximized to enhance mechanical performance. The findings show that the common practice of setting fixed layer times falls short of ensuring repeatable part quality. Full article

Friction is a pivotal factor influencing wrinkle formation in composite material shaping processes, particularly in novel thermoplastic composites like polyetheretherketone (PEEK) and low-melting polyaryletherketone (LM-PAEK) matrices reinforced with unidirectional carbon fibers. The aerospace sector lacks comprehensive data on the behavior of these materials under forming conditions, motivating this study’s objective to characterize the interlaminar friction of such high-performance thermoplastic composites across diverse temperatures and forming parameters. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to analyze the thermomechanical behaviors of PEEK and LM-PAEK. These data guided friction tests covering room-to-forming temperatures. Horizontal pull-out fixed-plies tests were conducted to determine the friction coefficient and shear stress dependency concerning temperature, pressure, and pulling rate. Below the melting point, both materials adhered to Coulomb’s law for friction behavior. However, above the melting temperature, PEEK’s friction decreased while LM-PAEK’s friction increased with rising temperatures. These findings highlight the distinct responses of these materials to temperature variations, pulling rates, and pressures, emphasizing the need for further research on friction characterization around glass transition and melting temperatures to enhance our understanding of this phenomenon. Full article

Manufacturing components using thermoplastic composite materials necessitates a judicious balance among fabrication parameters, cost considerations and the ultimate quality of the elements produced. Continuous manufacturing technologies, exemplified by methods such as continuous compressing molding and glide forming, seek to revolutionize production through their continuous processing approach. This study aimed to investigate the effects different process parameters have on the final quality of the manufactured parts when a continuous manufacturing technology, such as glide forming, is applied to thermoplastic composite materials. An experimental rig was designed, and 19 samples were prepared using a unidirectional-carbon-fiber-reinforced LM-PAEK (low-melting polyaryletherketone) composite. The process parameters studied were temperature, pressure and forming speed. The quality of the final parts was evaluated based on their thickness and consolidation levels. The findings underscore the feasibility of leveraging continuous manufacturing technologies for producing components using thermoplastic composite materials, but the process parameters must be carefully controlled to ensure the quality of the final part. The models obtained could be used as a post-processing tool to predict thickness and consolidation levels when simulating the manufacture of a component on macroscale levels. Further research is needed to optimize the process parameters and study their effects on other thermoplastic composite materials. Full article

This review aims to report the status of the research on polyaryletherketone-based thermoplastic blends (PAEK). PAEK are high-performance copolymers able to replace metals in many applications including those related to the environmental and energy transition. PAEK lead to the extension of high-performance multifunctional materials to target embedded electronics, robotics, aerospace, medical devices and prostheses. Blending PAEK with other thermostable thermoplastic polymers is a viable option to obtain materials with new affordable properties. First, this study investigates the miscibility of each couple. Due to different types of interactions, PAEK-based thermoplastic blends go from fully miscible (with some polyetherimides) to immiscible (with polytetrafluoroethylene). Depending on the ether-to-ketone ratio of PAEK as well as the nature of the second component, a large range of crystalline structures and blend morphologies are reported. The PAEK-based thermoplastic blends are elaborated by melt-mixing or solution blending. Then, the effect of the composition and blending preparation on the mechanical properties are investigated. PAEK-based thermoplastic blends give rise to the possibility of tuning their properties to design novel materials. However, we demonstrate hereby that significant research effort is needed to overcome the lack of knowledge on the structure/morphology/property relationships for those types of high-performance thermoplastic blends. Full article

Regarding the dynamic development of 3D printing technology, as well as its application in a growing part of industries, i.e., in the automotive industry, construction industry, medical industry, etc., there is a notable opportunity for its application in producing dental implants, which presents a promising alternative to traditional implant manufacturing methods. The medical industry is very restrictive regarding the applied materials, and it is necessary to use materials that exhibit very good mechanical and thermal parameters, show clinical indifference and biocompatibility, are non-allergenic and non-cancerous, and are likely to sterilize. Such materials are poly(aryl-ether-ketone)s (PAEK)s, mainly poly(ether-ether-ketone) (PEEK) and poly(ether-ketone-ketone) (PEKK), that are found to be high-performance polymers and can be defined as materials that retain their functionality even in extreme conditions. In the present paper, two types of PEEKs and PEKK were compared regarding their structural, mechanical, and thermal properties along with the biological activity toward selected strains. The tested samples were obtained with Fused Deposition Modeling (FDM) technology. The PEKK, after heat treatment, exhibits the most promising mechanical properties as well as less bacterial adhesion on its surface when compared to both PEEKs. Consequently, among the evaluated materials, PEKK after heat treatment stands out as the optimal selection for a dental prosthesis. Full article

Automated fiber placement (AFP) is a method to manufacture complex composite parts in an automatable and scalable process. Thermoplastic in situ AFP has received more attention in recent years for its use in high-performance, aerospace applications that use low-melting polyaryletherketone (LM-PAEK) composites. Although in situ AFP is a promising technology for the automated and economical manufacturing of composites, the production of a mold is still a considerable expense. Using large-scale additive manufacturing, molds can be manufactured in a short time frame for a fraction of the cost of traditional molds. By using polyamide 6 (PA6), a polymer incompatible with LM-PAEK, a bond can be created, which holds a laminate in the desired form during production and allows for demolding. Due to the thermoplastic nature of PA6, a mold can be manufactured using large-scale, extrusion-based additive manufacturing. This study investigates the suitability of 3D-printed molds composed of PA6 for the AFP of CF/LM-PAEK laminates. To this end, peel tests and shear tests were conducted to investigate the influence of the process temperature, the area of heating and the consolidation pressure on the bond of these incompatible polymers. A shear strength of up to 2.83 MPa and a peel strength of up to 0.173 N·mm⁻¹ were achievable. The principal suitability of PA6 as a mold material for the AFP of CF/LM-PAEK was demonstrated. Full article

Poly(aryl-ether-ketone) materials (PAEKs), a class of high-performance polymers comprised of polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), have attracted interest in standard dental procedures due to their inherent characteristics in terms of mechanical and biological properties. Polyetheretherketone (PEEK) is a restorative dental material widely used for prosthetic frameworks due to its superior physical, mechanical, aesthetic, and handling features. Meanwhile, polyetherketoneketone (PEKK) is a semi-crystalline thermoplastic embraced in the additive manufacturing market. In the present review study, a new way to fabricate high-performance polymers, particularly PEEK and PEKK, is demonstrated using additive manufacturing digital dental technology, or 3-dimensional (3D) printing. The focus in this literature review will encompass an investigation of the chemical, mechanical, and biological properties of HPPs, particularly PEEK and PEKK, along with their application particularly in dentistry. High-performance polymers have gained popularity in denture prosthesis in advance dentistry due to their flexibility in terms of manufacturing and the growing interest in utilizing additive manufacturing in denture fabrication. Further, this review also explores the literature regarding the properties of high-performance polymers (HPP) compared to previous reported polymers in terms of the dental material along with the current advancement of the digital designing and manufacturing. Full article

The microbiological behavior of dental polymer materials is crucial to secure the clinical success of dental restorations. Here, the manufacturing process and the machining can play a decisive role. This study investigated the bacterial adhesion on dental polymers as a function of manufacturing techniques (additive/subtractive) and different polishing protocols. Specimens were made from polyaryletherketone (PEEK, PEKK, and AKP), resin-based CAD/CAM materials (composite and PMMA), and printed methacrylate (MA)-based materials. Surface roughness (R_z; R_a) was determined using a laser scanning microscope, and SFE/contact angles were measured using the sessile drop method. After salivary pellicle formation, in vitro biofilm formation was initiated by exposing the specimens to suspensions of Streptococcus mutans (S. mutans) and Streptococcus sanguinis (S. sanguinis). Adherent bacteria were quantified using a fluorometric assay. One-way ANOVA analysis found significant influences (p < 0.001) for the individual parameters (treatment and material) and their combinations for both types of bacteria. Stronger polishing led to significantly (p < 0.001) less adhesion of S. sanguinis (Pearson correlation PC = −0.240) and S. mutans (PC = −0.206). A highly significant (p = 0.010, PC = 0.135) correlation between S. sanguinis adhesion and R_z was identified. Post hoc analysis revealed significant higher bacterial adhesion for vertically printed MA specimens compared to horizontally printed specimens. Furthermore, significant higher adhesion of S. sanguinis on pressed PEEK was revealed comparing to the other manufacturing methods (milling, injection molding, and 3D printing). The milled PAEK samples showed similar bacterial adhesion. In general, the resin-based materials, composites, and PAEKs showed different bacterial adhesion. Fabrication methods were shown to play a critical role; the pressed PEEK showed the highest initial accumulations. Horizontal DLP fabrication reduced bacterial adhesion. Roughness < 10 µm or polishing appear to be essential for reducing bacterial adhesion. Full article

The present paper reports the analyses of results obtained from experiments carried out to explore the challenge of homogeneous, uniform, and deagglomerated dispersion of ultra-heavy nanoparticles (NPs) in the high-performance polyaryletherketone (PAEK) matrix. An equal and fixed amount of (0.5 vol. %) NPs of silicon carbide (SiC), zirconium carbide (ZrC), and tungsten carbide (WC) were dispersed in a PAEK matrix and compression molded to develop three different nanocomposites. Simultaneously, nano-adhesives of the same composition were also developed to join the stainless steel adherends. The composites and adhesives were characterized for their physical, thermal, thermo-mechanical, thermal conductivity (TC), and lap shear strength (LSS) behavior. It was observed that SiC NPs performed significantly better than ZrC and WC NCs in all performance properties (LSS: 154%, TC: 263%, tensile strength: 21%). Thermal conductivity (TC) and tensile properties were validated using various predictive models, such as the rule of mixture parallel model, the Chiew and Glandt model, and the Lewis model. Scanning electron micrographs were used for the morphological analysis of LSS samples to detect macro- and micro-failure. Micrographs showed evidence of micro-striation and plastic deformation as a micromodel, as well as mixed failure, i.e., adhesive–cohesive as a macro-failure mode. Full article

Hydrogen fuel cell (FC) technologies are being worked on as a possible replacement for fossil fuels because they produce a lot of energy and do not pollute the air. In FC, ion-exchange membranes (IEMs) are the vital components for ion transport between two porous electrodes. However, the high production cost of commercialized membranes limits their benefits. Various research has focused on cellulose-based membranes such as IEM with high proton conductivity, and mechanical, chemical, and thermal stabilities to replace the high cost of synthetic polymer materials. In this review, we focus on and explain the recent progress (from 2018 to 2022) of cellulose-containing hybrid membranes as cation exchange membranes (CEM) and anion exchange membranes (AEM) for proton exchange membrane fuel cells (PEMFC) and alkaline fuel cells (AFC). In this account, we focused primarily on the effect of cellulose materials in various membranes on the functional properties of various polymer membranes. The development of hybrid membranes with cellulose for PEMFC and AFC has been classified based on the combination of other polymers and materials. For PEMFC, the sections are associated with cellulose with Nafion, polyaryletherketone, various polymeric materials, ionic liquid, inorganic fillers, and natural materials. Moreover, the cellulose-containing AEM for AFC has been summarized in detail. Furthermore, this review explains the significance of cellulose and cellulose derivative-modified membranes during fuel cell performance. Notably, this review shows the vital information needed to improve the ion exchange membrane in PEMFC and AFC technologies. Full article