PEEK/HAp

Poly(ether ether ketone) PEEK/HAp n/a 10-90 wt% n/a n/a Thermal analysis [110]... 

PEEK/HAp 25.8 im 0-40 vol% 2.8-16.0 45-69 Elame- spheroidized HAp, melt compounded, granulated and injection moulded [109]... 

The Young s modulus and the tensile strength of injection-moulded PEEK/HAp composites were reported to be in the range of 3-10 GPa and 40-90 MPa, respectively [106]. These results indicate that the mechanical properties of PEEK/HAp composites are in the region of cortical bone, making them a potential candidate for... 

Tan et al. [5] obtained 3D scaffolds using selective laser sintering (SLS) of PEEK/HAp biocomposites. Blends of PEEK/HAp were produced by mixing pure PEEK and HAp powders in different weight percentages using a roller-mixer the prepared powder blends were then processed using an SLS system (Fig. 8). 

Reports on the detailed thermal behaviour of PEEK/HAp composites [as well as other polymer/HAp (nano)composites] are scarce in the literature. Advanced thermal analysis methods, e.g., modulated temperature differential scanning calorimetry (MTDSC) or hyphenated thermoanalytical methods such as thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) or mass spectrometry... 

In the work of Meenan and coworkers [110], the thermal characterization of a series of PEEK/HAp composites was done by TG, DSC and MTDSC. The latter technique offers extended temperature profile capabilities by, e.g., sinusoidal wave superimposed to the normal linear temperature ramp. The capabilities of the MTDSC method in comparison with conventional DSC include separation of reversing (thermodynamic) and nonreversing (kinetic) components of the heat flow, improved resolution of closely occurring and overlapping transitions, and increased sensitivity of heat capacity measurements [111]. 

The authors found that an increase of HAp content in mixtures with PEEK causes a decrease of the onset temperature of PEEK degradation by up to 13°C. Water loss in the temperature range of 80-120°C and a slow dehydroxylation of the HAp, as the temperature increases over the range 200-750°C, were observed. Using MTDSC, the glass temperature (Tg) as well as the crystallization and melting temperatures Tc and T, respectively) of PEEK/HAp composites were accurately determined from the reversing component of the heat flow (Fig. 9) [110]. 

Fig. 9 Modulated temperature DSC scans for (a) 74/26% PEEK/HAp with Tg 142°C, Tc 160°C and 347°C and (b) 37/63% PEEK/HAp with Tg 141°C, Tc 160°C, Tm 347°C. In both plots the total heat flow signal (solid line) has been split into (i) the non-reversing (kinetic) and (ii) reversing (heat capacity) components. Reprinted from [110] with permission from Springer...

PEEK/HAp Compounding in the extruder, granulating and injection moulding [11, 108, 109]... 

The characteristic peaks of existing functional groups in PEEK, HAp-PEEK composite sintered at 350°C for 90 min and dry powder after in vitro study of HAp-PEEK composite sintered at 350°C for 90 min, known as SBF-sintered-HAp-PEEK-350°C, were charaeterized spectroscopic FTIR analysis as shown in Figure 7(b), (c) (d), respectively. However, there was no sharp characteristics peak for SBF crystals as shown in Figure 7(a). IR absorption peaks at around 1050 and 565 em were attributed for P04 vibration mode [2]. The small sharp peak at around 3600-3530 cm" was attributed to stretching vibration of molecular OH and the broad bands attributed to absorbed water (H2O) or hydrated OH" were also found at around 3500-3100 cm. ... 

The antibacterial behaviour of cold sprayed HAp-Ag (silver-doped hydrox-yapatite)/PEEK composite coatings were investigated against Escherichia coli (DH5a) by Sanpo et al. (2009). The antibacterial activity was found to increase with increasing concentration of HAp-Ag nanoparticles. The precursor nanocomposite powders were deposited using rather mild cold spraying parameters (11-12 bars, preheated air temperature between 150 and 160 °C). 

Fig. 8 SEM micrographs of sintered PEEK blend with (a) 10 wt% HAp, (b) 20 wt% HAp, (c) 30 wt%, and (d) 40 wt% HAp (HAp particles are circled). Reprinted from [5] with permission from Elsevier...

A prosthesis material using calcium phosphates-poly(ether etherketone)thermoplastic nano composite was developed. The nanosized calcium phosphates were synthesized by sol-gel technique. The biocompatibility test was carried out by SBF-conditioned study using freshly prepared simulated body fluid (SBF) at a temperature of 25-40°C and pH of 6.5-7.7. XRD was used to see the crystallinity and composition. The morphology and component distribution were performed by OM, SEM, AFM, etc. The functional groups present in composite materials were evaluated by FTIR. The growth study of SBF crystal was carried out by OM and XRD. The porous microsphere of HAp-PEEK composite was observed in SEM. 

Therefore, the main objective of this study is to develop another prosthesis materials using synthetic ceramic-thermoplastic nano composites. Here, we have used the synthetic HAp synthesized in wet chemical technique as ceramic and commercial grade PEEK as thermoplastic. 

The HAp-PEEK nano composite was prepared by melt blending process. In melt blending, 30 70 (w/w) of HAp and PEEK were mixed homogeneously. Finally, the composite was palletized in stainless steel mould followed by sintering at 350°C for 90 min to use for different characterizations. 

The biocompatibility property of HAp and HAp-PEEK nano composite pallets was carried out with in vitro study using freshly prepared SBF at temperature of 25-40°C and pH of 6.5-1.1. The growth study of SBF crystal was carried out in OM (Zeiss Axiolab Ltd. make, USA, model Image-Pro Plus V4.1) and XRD (Seifert Diffractometer make, England, model ISO Debyeflex-2002) using CuKa radiation (L = 1.54056 A). The crystallinity and compositional studies were carried out with XRD technique. 

Macro hardness of PEEK and HAp-PEEK composite, both sintered at 350°C, was measured by Rockwell hardness tester (Newage Testing Instruments, Inc make, model ME-2 Rockwell Hardness Testing System) using 1/16 steel ball and 60 kg applied load. Minimum five indentations were taken to obtain an average macro hardness value for each specimen. 

The morphology and component distribution of two phase particles were performed in secondary electron (SE) mode of scanning electron microscopy (SEM) as shown in Figure 4. The highly macro porous (white) HAp was formed good compatibility with PEEK matrix... 

The macro hardness value was carried out in order to evaluate the mechanical property of the pure PEEK and HAp-PEEK nano composite. The hardness value of 24.3 for pure PEEK was significantly improved at 64.5 by reinforcing of HAp particles in HAp-PEEK nano composite. However, few micro cracks were foimd beside the indentations of HAp-PEEK composites. This may due to the low bonding between HAp particles and PEEK polymer in sinto-ed HAp-PEEK composites. The indentations for pure PEEK sintered at 350"C and HAp-PEEK nano composite sinto-ed at 350"C specimens after hardness test are shown in Figures 8(a) and 8(b), respectively. 

Henee, the SBF-conditioned study with improved bioinert property of HAp-PEEK nano composite suggests a material for orthopedics prosthesis appUcations. 

Figure 3. X-ray diffraction pattern of (a) SBF crystal (PDF No. 05-0628), (b) PEEK, (c) HAp (PDF No. 34-0010) (d) HAp-PEEK (e) SBF-conditioned HAp and (f) SBF-conditioned HAp-PEEK composite.

Figure 4. Scanning electron micrograph of HAp-PEEK nano composite sinter at 350°C for 90 min, under 30,000x magnification.

Figure 5. Transmission electron micrograph of HAp-PEEK nano composite. 

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