Theoretical and experimental infrared spectra of hydrated and dehydrated sulfonated poly(ether ether ketone)

Effects of UV irradiation time on the molecular structure of typical engineering plastics and tribological properties under heavy load

Exposing engineering plastics to UV irradiation can easily destroy the original molecular structure of the materials and consequently affect their tribological properties. This study investigated the effects of UV irradiation on the molecular structure of typical engineering plastics, such as polytetrafluoroethylene (PTFE) and polyether ether ketone (PEEK), and on their tribological properties under heavy loads (20 MPa). The surface morphology results showed that the appearance of PEEK changed significantly under UV irradiation. However, the change in PTFE was negligible. Under micromorphology, the processing lines of the two materials gradually became lighter with increasing UV irradiation time. The resulting infrared spectra showed that the molecular chains of both materials were broken, and new functional groups were formed under UV irradiation. Tribology testing demonstrated that with prolonged UV irradiation, the average PTFE coefficient of friction remained relatively stable, whereas that of PEEK was approximately 0.55. As the UV irradiation time increased, the wear rate of PTFE increased significantly, whereas that of PEEK showed no significant change.

Preparation of hydroxyapatite-titanium particle hierarchical filled polyetheretherketone functional gradient biocomposites

Functional gradient biomaterials have been widely applied in the biomedical field due to their designable structure and performance. In this paper, hydroxyapatite-titanium particles hierarchical filled polyetheretherketone functional gradient biocomposites [(HA-Ti)/PEEK FGBm] were successfully fabricated through combination of a layer-by-layer casting method and hot pressing technology. The microstructure and morphology of the FGBm were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive X-ray analysis spectrometry (EDS) and scanning electron microscopy (SEM). The results of XRD and EDS verified that the components of the FGBm consist of HA, Ti and PEEK. FTIR and SEM studies showed that the existence of TiO2 thin film on the surface of Ti particles was beneficial to improve the wettability of Ti particles to the PEEK matrix, thus increasing the interfacial bonding strength between Ti particles and PEEK matrix. The SEM observation revealed that the size of HA particles in (HA-Ti)/PEEK FGBm was on the nano-scale and that of Ti particles was on the micron-scale. Furthermore, several typical microstructures such as micro-pores, dimple-like, and encapsulated-like morphologies in (HA-Ti)/PEEK FGBm were observed by SEM. With the rise of Ti and HA particle content in PEEK matrix, the distribution of them in PEEK matrix becomes more and more inhomogeneous and they tend to agglomerate.