A chemical bonding adhesive for PEEK based on aromatic ring interactions.

Objectives This paper describes the fabrication of a new porous 3D-printed scaffold composed of polycaprolactone (PCL) and polyether-ether ketone (PEEK) micro-particles for bone tissue engineering (BTE) applications. Methods In order to improve the compatibility of the reinforcing PEEK powder with polycaprolactone, the PEEK powder was surface-modified by an amino-silane coupling agent. After modification, Fourier-transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC) were used to investigate the chemical reaction between PEEK and silane coupling agent. In order to increase the compressive modulus of the 3D printed PCL scaffold, 10% silane-modified PEEK was incorporated into the PCL polymeric matrix. Scanning electron microscopy (SEM) was used for cell morphology and attachment evaluation. Results The results indicated that the silane coupling agent was successfully grafted onto the particle surface. The compressive modulus of PCL scaffold increased by incorporating the silane-modified PEEK, despite having higher porosity, compared with the pure PCL scaffolds. Addition of amino-silane had a positive impact on cell response, and that surface modification led to improved particle dispersion. Conclusion In conclusion, it seems that the incorporation of surface-modified PEEK micro-particles into the PCL porous scaffold could enhance its mechanical properties, and may be applicable for the management of large bone defects.

Crystallization kinetics of glass fiber filled poly(ether ether ketone) with nanogram sample size: Feasibility study for fast scanning calorimetry

Aims:The purpose of this study is to compare and evaluate the failure modes and load-bearing capacity of different surface-treated polyether ether ketone (PEEK) copings when veneered with lithium di-silicate with that of PEEK veneered with composite.Settings and Design:In vitro; comparative study.Materials and Methods:Congruently anatomically shaped single unit PEEK copings (n = 40) were fabricated by scanning a prepared typodont tooth. The PEEK copings were subdivided among four groups (n = 10/group). Among all, one group of PEEK coping was veneered with Urethane dimethacrylate (UDMA)-based composite and other groups were veneered with lithium-di-silicate after different surface treatment on peek copings, i.e., (i) composite veneered PEEK fixed dental prosthesis (FDP) (control group: Group PC), (ii) lithium di-silicate veneered PEEK FDP (no surface treatment: Group PCeN), (iii) lithium di-silicate veneered PEEK FDP (sandblasting with 50 μm alumina: Group PCeS), and (iv) lithium di-silicate veneered PEEK FDP (chemical etching with 98% sulfuric acid: Group PCeE). The load-bearing capacity of all specimens was assessed using a universal test machine. All the samples were loaded till the cracking point and load at that point and failure modes were noted down.Statistical Analysis Used:One-way ANOVA and post hoc Tukey tests.Results:The highest load-bearing capacity was recorded for lithium di-silicate veneered PEEK copings which were chemically etched with 98% sulfuric acid (Group PCeE: 1040.25 ± 77.46) followed by Group PCeS (1017.20 ± 53.70), then Group PC (965 ± 51.57) and least was for Group PCeN (933 ± 97.54). There was a significant reduction in mean load-bearing capacity in Group PCeN (P < 0.05).Conclusions:Veneering of PEEK with pressed lithium di-silicate seems to be a viable clinical option in terms of adequate load-bearing capacity. Lithium di-silicate veneered PEEK FDPs were successful against physiological occlusal forces and are a suitable material for FDPs.

Selective Laser Sintering (SLS) is one of the advanced additive manufacturing technologies which can build the geometrically complex structure from a three-dimensional CAD model. Poly ether ether ketone (PEEK) is one of the available materials for SLS and has received numerous interesting due to its excellent properties. In this research, a novel approach, thermally induced phase separation (TIPS) was employed to produce neat PEEK and PEEK/CNT composite powders with near spherical shape, desired particle size and size distribution for SLS application. Powders produced by TIPS demonstrated good flowability and processability. SEM images proved that CNT was embedded in PEEK powder. PEEK/CNT composite powder had shown an increased crystallinity in comparison with neat PEEK powder. Sintering rate of produced powders were studied with hot stage microscopy. Single layer films were built successfully by high temperature selective laser sintering (HT-SLS) using the powder developed via TIPS. Thermodynamics characteristics of single layer films were studied by DMA. Results revealed that addition of 0.1% CNT improved both storage and loss modulus of PEEK.

Poly ether ether ketone and its composite powder prepared by thermally induced phase separation for high temperature selective laser sintering

Porous and bioactive polyetheretherketone (PEEK) scaffolds have potential to replace metallic scaffolds for biologic fixation of permanent implants adjacent to trabecular bone, such as interbody spinal fusion devices. The objective of this study was to investigate the effects of the mold temperature and PEEK powder on the mechanical properties and crystallinity of hydroxyapatite (HA) whisker-reinforced PEEK scaffolds prepared using compression molding and porogen leaching. Scaffolds were prepared at mold temperatures ranging 340-390°C with a 50 or 10 μm PEEK powder, 75 vol% porosity, and 20 vol% HA whiskers. Scaffold mechanical properties were evaluated in unconfined, uniaxial compression and the PEEK matrix crystallinity was measured using specular reflectance Fourier transform infrared spectroscopy. Increased mold temperature resulted in increased compressive modulus, yield strength, and yield strain, reaching a plateau at ~370°C. HA reinforcements were observed to be segregated between PEEK particles, which inhibited PEEK particle coalescence during compression molding at temperatures less than 365°C but also ensured that bioactive HA reinforcements were exposed on scaffold strut surfaces. Increased mold temperature also resulted in decreased PEEK crystallinity, particularly for scaffolds molded at greater than 375°C. The PEEK powder size exhibited relatively minor effects on the scaffold mechanical properties and PEEK crystallinity. Therefore, the results of this study suggested that HA-reinforced PEEK scaffolds should be compression molded at 370-375°C. The apparent compressive modulus, yield strength, and yield strain for scaffolds molded at 370-375°C was 75-92 MPa, 2.0-2.2 MPa, and 2.5-3.6%, respectively, which was within the range exhibited by human vertebral trabecular bone.

The antibacterial and wear-resistant nano-ZnO/PEEK composites were constructed by a simple two-step method

Polyether ether ketone (PEEK) is a widely used material for friction pairs due to its excellent mechanical strength, good wear resistance, and chemical inertness. However, some modifications are necessary when PEEK is used as a water-lubricated friction pair. In this study, a novel sulfonation method was developed to design a water-lubricated friction pair with ultralow friction, good wear resistance, and high loading capacity. PEEK powders were sulfonated using ClSO3H and sintered to form bulk plastic. The sulfonated PEEK (SPEEK) plastic exhibited good tribological properties. At a low sliding speed, the friction coefficient was smaller than 0.02 when a 3 wt% NaCl solution was used as the lubricant. The order of magnitude of the wear rate was as low as 10−8 mm3/(N·m). The mechanism of friction reduction was mainly hydration lubrication. The negatively charged −SO3− groups on the friction pair can adsorb hydrated Na+ cations by electrostatic interactions. These hydrated Na+ cations have a high load capacity and low shearing resistance. The ultralow wear mechanism observed in this study is possibly due to ultralow friction properties of the friction pairs prepared through the proposed sulfonation and thermoforming procedures.

Amorphous-to-crystalline transition of Polyetheretherketone–carbon nanotube composites via resistive heating

ABSTRACTIn this work, manufacturing and characterization of single‐ and multilayer polyether ether ketone (PEEK)‐reinforced coatings were investigated. Hybrid composites of thermoplastic reinforcing agents in a thermoset resin was, therefore, achieved by dispersing large PEEK particles (∼85 μm diameter) in methyl phenyl polysiloxane (MPP). First, mechanism of formation of the polymeric networks during MPP curing at different temperatures (250–400 °C) was analyzed. The different arrangements of the PEEK powders inside the cross‐linked network of the MPP resin were, thus, disclosed. Second, the effect of process parameters on visual appearance, morphological features, and mechanical response of the composite coatings was evaluated by contact gauge profilometry, scanning electron microscopy, IR spectrometry, and microscratch indentations. Moderate temperature curing (250 °C &gt; T &gt; 300 °C) of the composite coatings led to polysiloxane resins harder, well adhered on the metal and able to retain better the PEEK reinforce. Further increase in curing temperature (350 and 400 °C) might embrittle the polysiloxane resin, with the PEEK powders in it partially attenuating the loss of properties of the composite coating. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43609.

Abstract: Purpose: to evaluate the effect of repeated heat pressing and thermocycling on micro-shear bond strength of PEEK to resin cement. Methods: A total of 30 PEEK specimens 10 mm x 10 mm x 2 mm were prepared and divided to three groups (n=10). Group I was pressed using new PEEK, Group II ; 50% new PEEK and 50% reprocessed PEEK, and Group III ; 100% reprocessed PEEK. Bonding surfaces were sandblasted and thin layer of bonding agent was applied and polymerized. Plastic tygon tubes with an inner diameter of 1 mm and a height of 1.5 mm were fixed on the sample and filled with dual polymerized self etch self adhesive resin cement and cured. Half the specimens in each group (n=5) underwent 5000 thermocycles (5‐55°C) before shear bond strength (µSBS) test. Two-way Analysis of Variance (ANOVA) studied the effect of PEEK condition, thermocycling and their interaction on mean micro-shear bond strength µSBS. Bonferroni’s post-hoc test was used for pair-wise comparisons when ANOVA test is significant. Results: The PEEK condition (regardless of thermocycling) had a statistically significant effect on mean µSBS (P-value = 0.001, Effect size = 0.455). Thermocycling (regardless of PEEK condition) also had a statistically significant effect on mean µSBS (P-value = 0.002, Effect size = 0.331). The interaction between two variables had no statistically significant effect on mean µSBS (P-value = 0.442, Effect size = 0.066). Conclusion: Both repeated heat pressing and thermocycling had a negative effect on micro-shear bond strength of resin cement to PEEK

An in vivo study examining the functional osseointegration of smooth, rough, and porous surface topographies presenting polyether-ether-ketone (PEEK) or titanium surface chemistry. To investigate the effects of surface topography and surface chemistry on implant osseointegration. Interbody fusion devices have been used for decades to facilitate fusion across the disc space, yet debate continues over their optimal surface topography and chemistry. Though both factors influence osseointegration, the relative effects of each are not fully understood. Smooth, rough, and porous implants presenting either a PEEK or titanium surface chemistry were implanted into the proximal tibial metaphyses of 36 skeletally mature male Sprague Dawley rats. At 8 weeks, animals were euthanized and bone-implant interfaces were subjected to micro-computed tomography analysis (n = 12), histology (n = 4), and biomechanical pullout testing (n = 8) to assess functional osseointegration and implant fixation. Micro-computed tomography analysis demonstrated that bone ingrowth was 38.9 ± 2.8% for porous PEEK and 30.7 ± 3.3% for porous titanium (P = 0.07). No differences in fixation strength were detected between porous PEEK and porous titanium despite titanium surfaces exhibiting an overall increase in bone-implant contact compared with PEEK (P < 0.01). Porous surfaces exhibited increased fixation strength compared with smooth and rough surfaces regardless of surface chemistry (P < 0.05). Across all groups both surface topography and chemistry had a significant overall effect on fixation strength (P < 0.05), but topography accounted for 65.3% of the total variance (ω = 0.65), whereas surface chemistry accounted for 5.9% (ω = 0.06). The effect of surface topography (specifically porosity) dominated the effect of surface chemistry in this study and could lead to further improvements in orthopedic device design. The poor osseointegration of existing smooth PEEK implants may be linked more to their smooth surface topography rather than their material composition. N/A.

Influence of polyether ether ketone (PEEK) viscosity on interlayer shear strength in screw extrusion additive manufacturing

Strength of functionally gradient composite hemispherical bearings

Event Abstract Back to Event Bioactive nano fluorapatite/polyetheretherketone composite for orthopedic Implants Liang Cai1 and Jie Wei1 1 East China University of Science and, School of Materials Science and Engineering, China Introduction: Nano fluorapatite (n-FA) is a bioactive material with chemical and crystallographic similarity to that of natural apatite in bones and dentals, and has been currently used in hard tissue engineering for bone regeneration. Furthermore, the effects of FA on oral bacteria and plaque due to the release of fluorine ions, which can act as an antimicrobial agent, are well documented by a considerable amount of literature[1]. Lack of antibacterial activity and binding ability to natural bone tissue has significantly limited polyetheretherketone (PEEK) for many challenging in bone implant applications[2]. Hence, we have developed the n-FA/PEEK composite and evaluated the antibacterial activity and osseointegration. Materials and Methods: The PEEK powder and n-FA powder were mixed together to obtain a homogeneous powder mixture via solvent evaporation method. Then the compression molding method was used to fabricate n-FA/PEEK composite. The hydrophilicity of n-FA/PEEK was evaluated via water contact angle test, the mechanical strength was tested by mechanical testing machine, and the antibacterial ability of composite was evaluated by Live/Dead cell staining. The MG-63 cells were cultured on the composites with different time, and the cell attachment, proliferation and differentiation were evaluated by confocal laser scanning microscope (CLSM), CCK-8 assay and alkaline phosphatase (ALP) activity, respectively. The Micro CT, histological and immunostaining analysis were used to evaluated osteoconductivity of composite, which the composite samples were implanted into the femoral bone of rabbits with different time. Results and discussions: The results showed that the hydrophilicity and mechanical strength of the composite obviously improved as compared with PEEK. In addition, the composite could inhibit bacterial attachment, with the number of viable bacteria on the composite obviously lower than on PEEK, indicating good antibacterial ability. Moreover, the attachment and proliferation of MG-63 cells on the composite was significantly higher than on PEEK, and the ALP of the cells on the composite was expressed at significantly higher levels compared to PEEK. Furthermore, the cells showed intimate contact with the composite surface and the cells spread and grew significantly better on the composite as compared with PEEK. Therefore, incorporation of n-FA into PEEK is a good method to prepare an inorganic–organic bioactive composite of nanometer inorganic materials and polymers, which supports cell attachment, proliferation and differentiation. The implantation of the composite into the femoral bone of rabbits showed that the new bone tissue could form on the composite surfaces, and the composite combined directly with the natural bone tissue without fibrous capsule tissue, showing good osseointegration. Conclusions: In short, the n-FA/PEEK biocomposite with good biocompatibility and bioactivity might be a promising implant material for using in orthopedic clinics.