Commercial Poly Ether Ether Ketone Research Articles

Dodging reality, striking the virtual: An undulating strategy for effectively enhancing CF/PEEK interfacial adhesion!

The design of carbon fiber (CF)-reinforced polyetheretherketone (PEEK) composite materials with suitable interfaces has consistently been challenging. In this study, we sulfonated poly (phthalazinone ether sulfone ketone) (PPESK) and PEEK to prepare water-soluble SPPESK and SPEEK. Subsequently, we prepared a water-soluble sizing agent (SPPESK/SPEEK) via a straightforward blending process. This sizing agent tended to accumulate randomly on the surfaces of CFs, forming a thin film with a heterogeneous structure in the nanoscale. At the molding temperature of the composite material, the two components on the fiber surface exhibited different rheological behaviors, with PEEK preferentially infiltrating the SPEEK region, forming strong molecular entanglements. Meanwhile, the SPPESK region provided a rigid supportive structure, offering the potential for the mechanical interlocking of PEEK in the interface layer. The performance of the prepared composite materials was significantly enhanced, with their interlaminar shear strength and flexural strength reaching 87.1 MPa and 975.8 MPa, respectively. With respect to those of commercial fiber-reinforced PEEK composites, an 89.8 % increase in interlaminar shear strength and a 79.39 % increase in flexural strength were observed. This interface reinforcement mechanism presents a universally applicable strategy for the future development of fiber-reinforced composite materials.

Feasibility of 3D-Printed Locking Compression Plates with Polyether Ether Ketone (PEEK) in Tibial Comminuted Diaphyseal Fractures.

The applicability of a polyether ether ketone locking compression plate (PEEK LCP) fabricated using FDM (fused deposition modeling)-based 3D printing to treat actual patients was studied. Three different tests-bending, axial compression, and axial torsion-were conducted on tibial non-osteoporotic comminuted diaphyseal fracture samples fixed with the commercial titanium alloy LCP and 3D-printed PEEK LCP. Comparing the outcomes of these tests revealed that the commercial titanium alloy LCP underwent plastic deformation in the bending and axial torsion tests, though the LCP did not fail even when an external force greater than the maximum allowable load of the tibia fixture of the LCP was applied. Elastic deformation occurred in the 3D-printed PEEK LCP in the bending and axial torsion tests. However, deformation occurred even under a small external force, and its stiffness was 10% compared to commercial titanium alloy LCP. Thus, 3D-printed PEEK LCP can be applied to the fracture conditions in non-weight-bearing regions. The experimental results reveal detailed insights into the treatment of actual patients by considering the stiffness and high toughness of 3D-printed PEEK LCP.

Fracture Characteristics of Commercial PEEK Dental Crowns: Combining the Effects of Aging Time and TiO2 Content.

Polyetheretherketone (PEEK) is an emerging thermoplastic polymer with good mechanical properties and an elastic modulus similar to that of alveolar bone. PEEK dental prostheses for computer-aided design/computer-aided manufacturing (CAD/CAM) systems on the market often have additives of titanium dioxide (TiO2) to strengthen their mechanical properties. However, the effects of combining aging, simulating a long-term intraoral environment, and TiO2 content on the fracture characteristics of PEEK dental prostheses have rarely been investigated. In this study, two types of commercially available PEEK blocks, containing 20% and 30% TiO2, were used to fabricate dental crowns by CAD/CAM systems and were aged for 5 and 10 h based on the ISO 13356 specifications. The compressive fracture load values of PEEK dental crowns were measured using a universal test machine. The morphology and crystallinity of the fracture surface were analyzed by scanning electron microscopy and an X-ray diffractometer, respectively. Statistical analysis was performed using the paired t-test (α = 0.05). Results showed no significant difference in the fracture load value of the test PEEK crowns with 20% and 30% TiO2 after 5 or 10 h of aging treatment; all test PEEK crowns have satisfactory fracture properties for clinical applications. Fracture surface analysis revealed that all test crowns fractured from the lingual side of the occlusal surface, with the fracture extending along the lingual sulcus to the lingual edge, showing a feather shape at the middle part of the fracture extension path and a coral shape at the end of the fracture. Crystalline analysis showed that PEEK crowns, regardless of aging time and TiO2 content, remained predominantly PEEK matrix and rutile phase TiO2. We would conclude that adding 20% or 30% TiO2 to PEEK crowns may have been sufficient to improve the fracture properties of PEEK crowns after 5 or 10 h of aging. Aging times below 10 h may still be safe for reducing the fracture properties of TiO2-containing PEEK crowns.

Material extrusion-based additive manufacturing of polyetheretherketone cranial implants: Mechanical performance and print quality

Polyetheretherketone (PEEK) is considered a ‘gold-standard’ material choice for cranial bone reconstruction. The introduction of additive manufacturing (AM) into the pipeline for patient specific cranial implant (PSCI) fabrication could accelerate supply chain needs and improve patient outcomes. Fused filament fabrication (FFF), a material extrusion-based technology, is a much-researched process due to its accessibility and ease of use. However, the quality of PEEK processed by FFF is highly affected by the applied printing profile. Therefore, in this study, the effects of printing parameters such as build orientation and air flow temperature on mechanical performance (cyclic and impact tests) and implant quality (characterisation of surface topography, discoloration and crystallinity) were analysed and compared with a commercial milled PEEK implant. It has been found that horizontally printed implants show higher mechanical integrity compared to implants printed upright or tilted by 45°, but obtain lower surface quality. In addition, lower air flow temperatures lead to strong implant discolorations due to high amounts of amorphousness, which further result in high absorbed energies during impact as well as large deformations until complete failure. The best results from a mechanical point of view were achieved with PSCIs printed at a build orientation of 180°, an air flow temperature of 210 °C, a shell number of 3, a layer height of 0.15 mm, a printing speed of 50 mm/min, a rectilinear ±45° infill pattern and an implant thickness of 5 mm. However, the surface quality of implants produced this way is not completely satisfactory, and the arrangement of the support structures must be further improved.

Influence of Aging on the Fracture Characteristics of Polyetheretherketone Dental Crowns: A Preliminary Study.

Although polyetheretherketone (PEEK) is becoming more widely used in dentistry applications, little is known about how aging will affect this material. Therefore, this study aimed to investigate the influence of an aging treatment on fracture characteristics of PEEK dental crowns. Additionally, the impact of the addition of titanium dioxide (TiO2) into PEEK was examined. Two types of commercial PEEK discs were used in this study, including TiO2-free and 20% TiO2-containing PEEK. The PEEK dental crowns were fabricated and aging-treated at 134 °C and 0.2 MPa for 5 h in accordance with the ISO 13356 specification before being cemented on artificial tooth abutments. The fracture loads of all crown samples were measured under compression tests. Results demonstrated that adding TiO2 enhanced the fracture load of PEEK crowns compared to TiO2-free PEEK crowns before the aging treatment. However, the aging treatment decreased the fracture load of TiO2-containing PEEK crowns while increasing the fracture load of TiO2-free PEEK crowns. The fracture morphology of TiO2-containing PEEK crowns revealed finer feather shapes than that of the TiO2-free PEEK crowns. We concluded that adding TiO2 increased the fracture load of PEEK crowns without aging treatment. Still, the aging treatment influenced the fracture load and microscopic fracture morphology of PEEK crowns, depending on the addition of TiO2.

Investigation of Ionic Liquid/Membrane Matrix for the Mid Temperature PEM Fuel Cell

Operating polymer electrolyte fuel cells (PEFC) >100 °C allows a significant simplification of the necessary peripheral devices. It allows operation without feed gas humidification—respectively no water recyclation—and a more efficient cooling system. For operation temperatures <80 °C, PEFCs with NAFION® membranes show excellent electrochemical performance. However, at higher temperatures sulfonated fluoropolymer membranes suffers from the drying effects at atmospheric operation which leads to a dramatic decrease of the proton conductivity. When using phosphoric acid (H3PO4) doped polybenzimidazole membranes (PBI), a PEFCs can be operated in the temperature range of 160–180 °C (HT-PEFC). Nevertheless, due to poisoning effects by H3PO4 and its anionic species on the redox catalyst platinum and a low solubility of oxygen in H3PO4, the ORR kinetics is rather sluggish and leads to an insufficient power density. Moreover, at temperatures <150 °C the proton conductivity is not sufficient.Thus, there is need for new proton conducting membrane materials for operation temperatures of 100–120 °C, whose conductivity is not related to a high degree of water swelling. Proton conducting ionic liquids (PILs) exhibit a high proton conductivity, low volatility and high thermal stability, as well as a high electrochemical stability over a wide temperature range [1-3]. Thus, PILs are the promising candidates as non-aqueous proton conductors.This experimental study is focused on high Brønsted-acidic sulfoalkylammonium type PILs as 2-sulfoethylmethylammonium triflate [MSEA][TfO], 2-sulfoethylmethylammonium hydrogen sulfate [MSEA][HSA], 3-sulfopropyldiethylammonium triflate [DESPA][TfO] and 3-sulfopropyldiethylammonium hydrogen sulfate [DESPA][HSA]. The physico-chemical properties of the neat PILs, i.e. ORR kinetic current density, oxygen solubility, oxygen diffusivity, electric conductivity and thermal stability, are measured at temperatures relevant for fuel cell operation. Commercial polyetheretherketone (PEEK) and PBI are chosen as host membrane materials to immobilize the PILs in a polymer matrix. The (total) electric conductivity and the thermal stability of the PIL-polymer systems are also evaluated.The influences of the cations or anions on the PILs and the different immobilization methods of PILs in membrane are investigated. The results show that with different PIL/membrane combinations, significant differences in thermal stability, mechanical stability and electric conductivity are present.Literature:[1] Yasuda, T. and M. Watanabe, Protic ionic liquids: fuel cell applications. MRS Bull., 2013. 38(7): p.560-566.[2] Noda, A., K. Hayamizu, and M. Watanabe, J. Phys. Chem. B, 2001 105(20): p. 4603-4610.[3] Huang, X.-J., et al., J. Phys. Chem. B, 2009. 113(26): p. 8953-8959.

Design and Biomechanical Verification of Additive Manufactured Composite Spinal Cage Composed of Porous Titanium Cover and PEEK Body

Incidents of lumbar degenerative diseases, such as spinal stenosis and degenerative spondylolisthesis, are increasing due to the aging population, and as a result, posterior lumbar interbody fusion (PLIF) is widely used. However, the interbody fusion cage used in the fusion surgery has been reported to cause subsidence in the fusion cage of the titanium material and bone nonunion in the case of the polyetheretherketone (PEEK) material cage. Therefore, we aim to reduce the possibility of subsidence of the spinal fusion cage through its elastic modulus difference with the cortical bone of the vertebral body. For the vertebral end plate, which is related to the fusion rate, we also aim to design a new composite vertebral cage, which integrates a cover of porous structure using the additive manufacturing method of titanium alloy to fabricate a prototype, and to biomechanically verify the prototype. The method was as follows. In order to find a similar pore size of human cancellous bone, the pore size was adjusted and the results were measured with SEM. The pore size of each surface was measured individually and the mean value was calculated. Next, an animal experiment was conducted to confirm the degree of fusion of each structural type, and prototypes of various structures were fabricated. The degree of fusion was confirmed by a push down test. A prototype of the fusion cage composed of titanium and PEEK material was fabricated, and the possibility of subsidence by existence of porous structure was confirmed by using the lumbar spine finite element model. Then, the prototype was compared with the composite fusion cage developed by ASTM F2077 and ASTM F2267 methods, and with the commercial PEEK and titanium cages. As a result, the correlation between bone fusion and the porous structure, as well as size of the spine fusion cage composing the composite for porous structure and elasticity, was confirmed. Type 3 structures showed the best performance in bone fusion and the pore size of 1.2 mm was most suitable. In addition, the likelihood of subsidence of a cage with a porous structure was considered to be lower than that of a cage with a solid structure. When the new composite cage combined with two composites was compared with commercial products to verify, the performance was better than that of the existing PEEK material. The subsidence result was superior to the titanium product and showed similar results to PEEK products. In conclusion, the performance value was superior to the existing PEEK material, and the subsidence result was superior to the titanium product and was similar to the PEEK product, and thus, performance-wise, it is concluded that the PEEK product can be completely replaced with the new product.

Room temperature extrusion 3D printing of polyether ether ketone using a stimuli-responsive binder

We report our efforts toward 3D printing of polyether ether ketone (PEEK) at room temperature by direct-ink write technology. The room-temperature extrusion printing method was enabled by a unique formulation comprised of commercial PEEK powder, soluble epoxy-functionalized PEEK (ePEEK), and fenchone. This combination formed a Bingham plastic that could be extruded using a readily available direct-ink write printer. The initial green body specimens were strong enough to be manipulated manually after drying. After printing, thermal processing at 230 °C resulted in crosslinking of the ePEEK components to form a stabilizing network throughout the specimen, which helped to preclude distortion and cracking upon sintering. A final sintering stage was conducted at 380 °C. The final parts were found to have excellent thermal stability and solvent resistance. The Tg of the product specimens was found to be 158 °C, which is 13 °C higher than commercial PEEK as measured by DSC. Moreover, the thermal decomposition temperature was found to be 528 °C, which compares well against commercial molded PEEK samples. Chemical resistance in trifluoroacetic acid and 8 common organic solvents, including CH2Cl2 and toluene, were also investigated and no signs of degradation or weight changes were observed from parts submerged for 1 week in each solvent. Test specimens also displayed desirable mechanical properties, such as a Young’s modulus of 2.5 GPa, which corresponds to 63% of that of commercial PEEK (reported to be 4.0 GPa).

Finite element analysis of the biomechanical effects of PEEK dental implants on the peri-implant bone

Dental implants are mostly fabricated of titanium. Potential problems associated with these implants are discussed in the literature, for example, overloading of the jawbone during mastication due to the significant difference in the elastic moduli of titanium (110GPa) and bone (≈1–30GPa). Therefore poly-ether-ether-ketone (PEEK) could represent an alternative biomaterial (elastic modulus 3–4GPa). Endolign® represents an implantable carbon fiber reinforced (CFR)-PEEK including parallel oriented endless carbon fibers. According to the manufacturer it has an elastic modulus of 150GPa. PEEK compounds filled with powders show an elastic modulus around 4GPa.The aim of the present finite element analysis was to point out the differences in the biomechanical behavior of a dental implant of Endolign® and a commercial powder-filled PEEK. Titanium served as control.These three materials were used for a platform-switched dental implant-abutment assembly, whereas Type 1 completely consisted of titanium, Type 2 of a powder-filled PEEK and Type 3 of Endolign®. A force of 100N was applied vertically and of 30° to the implant axis.All types showed a minimum safety factor regarding the yield strength of cortical bone. However, within the limits of this study the Type 2 implant showed higher stresses within the adjacent cortical bone than Type 1 and Type 3. These implant assemblies showed similar stress distributions.Endless carbon fibers give PEEK a high stability. Further investigations are necessary to evaluate whether there is a distinct amount of endless carbon fibers causing an optimal stress distribution behavior of CFR-PEEK.

Development of a Low-Cost Polymethylmethacrylate Stand-Alone Cervical Cage: Technical Note

Stand-alone cervical cages aim to provide primary stability, yield solid fusion in the long-term course, and maintain physiologic alignment. However, many implants designed for these purposes fail in achieving these goals. Following implantation, relatively high rates of cage subsidence and failure of disc height maintenance may lead to cervical kyphosis and poor alignment of the cervical spine. At the same time, costs for cage implantation are relatively high compared with their unfavorable radiologic performance. Thus the aim of the study was to develop and test mechanically a low-cost polymethylmethacrylate (PMMA) cage with similar mechanical and procedural properties compared with a commercial polyetheretherketone (PEEK) cage. Following determination of the cage design, a casting mold was developed for the production of PMMA cages. Nine cages were produced and compared with nine PEEK cages using static compression tests for 0 and 45 degrees according to the recommendations of the American Society for Testing and Materials. Mean compressive yield strength, mean yield displacement, mean tensile strength, and mean stiffness were determined. At 0 degrees axial compression, the mean compressive yield strength, mean displacement, and mean tensile strength of the PMMA cage was significantly higher compared with the PEEK cage (p < 0.001). Stiffness of both implants did not differ significantly (p = 0.903). At 45 degrees axial compression, PEEK cages could not be investigated because slipping of the holding fixture occurred. Under these conditions, PMMA cages showed a mean compressive yield strength of 804.9 ± 60.5 N, a mean displacement of 0.66 mm ± 0.05 mm, a mean tensile strength of 7.92 ± 0.6 N/mm(2), and a mean stiffness of 1,228 ± 79.4 N/mm. The newly developed PMMA cage seems to show similar to superior mechanical properties compared with the commercial PEEK cage. Considering a preparation time of only 10 minutes and the low price for the PMMA material, the cost-benefit ratio clearly points to the use of the PMMA cage. However, clinical effectiveness has to be proven in a separate study.

A covalent organic/inorganic hybrid proton exchange polymeric membrane: synthesis and characterization

Commercial polyetheretherketone (Victrex PEEK) was sulfonated up to 90% degree of sulfonation (DS), then reacted with SiCl 4 to obtain a hybrid polymer. The product was characterized by 29Si NMR and ATR/FTIR spectroscopies demonstrating the formation of covalent bonds between the organic and inorganic components. No dispersed inorganic silicon was present in the product as evidenced by the lack of any resonance at δ<−100 ppm. Despite the high DS the physicochemical properties of the hybrid were suitable for the preparation of membranes exhibiting high and stable conductivity values (10 −2 S/cm), hence suitable for application as ion exchange membrane.

On-line sorption preconcentration of chromium(VI) and its determination by flame atomic absorption spectrometry

A method was developed for the determination of Cr(VI) by flame atomic absorption spectrometry (FAAS) after on-line sorption preconcentration. The solution containing Cr(VI) was reacted with ammonium-pyrrolidinedithiocarbamate (APDC) in a flow injection manifold system designed for this purpose and the non-water soluble chromium complex formed was adsorbed in a sorption reactor. The commercial PEEK (polyether ether ketone) loop used in liquid chromatography (LC) was introduced instead of a knotted reactor recommended for preconcentration of other trace elements in the literature. The Cr-PDC complex was retained by the PEEK loop, from which the chromium complex could be eluted rapidly by methyl isobutyl ketone into the flame. The PEEK loop is cheaper than the LC column used previously for preconcentration of Cr(VI), it can easily be inserted into the system and it is practically of unlimited lifetime. The preconcentration could also be done at much greater flow rates than that for columns because of the little hydrodynamic resistance of the loops. Thus the duration of the determination could considerably be reduced. The preconcentration of 5 ml of Cr(VI) sample and FAAS determination could be carried out within 2 min. The enrichment factor was 65. The detection limit (3 σ) was 2.0 ng ml −1. The relative standard deviation was 2.1% for 50 ng ml −1 and 6.8% for 5 ng ml −1 Cr(VI) ( N=5). The proposed method was applied for determination of Cr(VI) in various water and cigarette ash samples.