The synthesis and characterization of poly(phthalazinone ether ketone) (PPEK) for high-temperature electric energy storage applications is described. It was found that PPEK displayed excellent stability of the dielectric properties over a broad frequency and temperature range. Little change in the breakdown field and discharge time has been observed in PPEK with the increase of temperature up to 190 degrees C. A linear correlation between the AC conductance and the angular frequency implied that the hopping as a dominant conduction process contributed to the dielectric loss. Superior energy densities, remarkable breakdown strengths, and fast discharge speeds have been demonstrated in PPEK at various temperatures.

The dielectric constant and loss of poly(ether ketone ketone) have been investigated over a range of frequency and temperature. A linear correlation between the ac conductance and the angular frequency implies that the hopping as a dominant conduction process contributes to the dielectric loss. The energy density and discharged efficiency of the polymer were measured at various temperatures. High dielectric strengths (>400 MV/m) at temperatures up to 150 °C have been achieved. The increase of the dielectric loss and reduction in the breakdown field with increasing temperature could be attributed to thermally enhanced conduction of charge carriers in the polymer.

Interest in carbon fiber reinforced composites based on polyaryl ether ketones (PAEKs) continues to grow, and is driven by their increasing use as metal replacement materials in high temperature, high-performance applications. Though these materials have seen widespread use in oil, gas, aerospace, medical and transportation industries, applications are currently limited by the thermal and mechanical properties of available PAEK polymer chemistries and their carbon fiber composites as well as interfacial bonding with carbon fiber surfaces. This article reviews the state of the art of PAEK polymer chemistries, mechanical properties of their carbon fiber reinforced composites, and interfacial engineering techniques used to improve the fiber-matrix interfacial bond strength. We also propose a roadmap to develop the next generation of high-performance long fiber thermoplastic composites based on PAEKs.

Bioactive surface-porous polyetherketoneketone materials (PEKK-BSP) were prepared by first leaching hydroxyapatite (HA) microsphere templates from compression molded PEKK/HA composites (i.e., PEKK-P) followed by sulfonation with 80% sulfuric acid for 3 h (i.e., PEKK-SP) and then soaking in a simulated body fluid (SBF) for 5 days. The combination of both physical and chemical processes created a surface-porous PEKK material (PEKK-SP) that had both structurally interconnected and open macropores (200–600 μm) because of templating of HA microspheres, and micropores (<10 μm) due to effects of the sulfonation. The in vitro bioactivity of PEKK-SP was demonstrated by the development of a dense layer of bone-like apatite inside and on the surfaces after SBF treatment. The sulfonation process followed SBF treatment also significantly reduced the water contact angle of PEKK material. Mechanical tests showed that both PEKK-BSP and PEKK-P were a little better than PEKK-SP in terms of compressive strength and modulus. In vitro cell culture using rabbits’ mesenchymal stem cells (MSCs) demonstrated that PEKK-BSP promoted better cell growth and proliferation than other groups of PEKK materials. Moreover, compared to PEKK material alone, PEKK-BSP elevated gene expressions of osteocalcin (OCN), Type I collagen (Col-I), alkaline phosphatase (ALP), and runt-related transcription factor 2 (Runx2). This bioactive PEKK-BSP material has potential application for spinal interbody fusion devices to enhance their in vivo osseointegration.