On the Structural, Thermal, Micromechanical and Tribological Characterizations of Cu-Filled Acrylonitrile Butadiene Styrene Micro-Composites

The purpose of this work was to investigate the structural, thermal, micromechanical and tribological properties of novel polymer/metal composite materials for bearing applications. Copper (Cu)-filled Acrylonitrile Butadiene Styrene (ABS) composites were mixed in a laboratory scale by an internal mixer with two blade impellers, and then injection-molded. Neat ABS, ABS+5wt% Cu, ABS+10wt% Cu, and ABS+15wt% Cu were the four materials that were tested. The dispersion of Cu particles in the ABS matrix was investigated using Scanning Electron Microscopy (SEM) and a micro-tomography scan. The filler particles have a uniform distribution in the matrix, according to the observations. The incorporation of Cu filler also refined an increase in the glass transition temperature from Differential Scanning Calorimetry (DSC) and less intensity in the amorphous phase by X-ray diffraction (XRD). Nanoindentation tests were carried out to characterize the micro-mechanical behavior of the composites. Friction and wear analysis were also examined using a pin-on-disk tribometer. Compared with neat ABS, all the micro-composites showed much higher indentation hardness, Vickers hardness, and indentation elastic modulus. It was also concluded that the incorporation of Cu filler into ABS simultaneously improved the friction and wear properties of the composites, which contributed to the suitability of the micro-filled composites with hard metallic particles for a wider range of mechanical components for bearing applications.

Friction and wear characteristics of synthetic diamond and graphene-filled polyether ether ketone composites

Modifying tribo films using filler particles is a significant area of research in developing polymer-based tribo components to minimize material loss during the sliding process. This study focused on altering the wear characteristics of a polyetheretherketone (PEEK)/graphene high-performance polymer composite to strengthen the tribo film by adding synthetic diamond particles. The hot-pressed PEEK composite reinforced by graphene and diamond particles increased the hardness and thermal stability of the composite. Compared with pure PEEK, composites containing 1% graphene and 1% diamond particles showed an increment of 25% and 23% in hardness and thermal stability, respectively. Fourier-transform infrared spectroscopy and X-ray diffraction analysis verified the compatibility and intactness of the fillers in the PEEK matrix. The tribo properties of PEEK composites were characterized by a pin-on-disc tribometer on a counter steel surface. A PEEK composite containing 0.75 wt% graphene and 0.5 wt% diamond particles exhibited the lowest friction of 0.17 at a pressure of 1.5 MPa. The specific wear rate was low (1.78 × 10−6 mm3/Nm) for the composite containing 1 wt% graphene and 1 wt% diamond particles at a pressure of 1.5 MPa. Varying synthetic diamond and graphene filler concentrations in the PEEK matrix change the wear process by modifying the tribo film characteristics, revealing the lowest friction and wear rate. X-ray photoelectron and Raman spectroscopy show that the polymer film was transferred to the steel countersurface, and the tribo-chemical products of the tribo film contribute to a stable tribo film. The ferric oxide film and the tribo film improve the composite’s self-lubricating properties and load-bearing ability. Hence, the composite containing 0.75% of graphene and 0.5% of a synthetic diamond can be employed in the sliding bearing application of continuous conveyors used in mass production systems.

Nanomaterial reinforced composite for biomedical implants applications: a mini-review

There is heavy demand for suitable implant materials with improved mechanical and biological properties. Classically, the demand was catered by conventional materials like metals, alloys, and polymer-based materials. Recently, nanomaterial reinforced composites have played a significant role in replacing conventional materials due to their excellent properties such as biocompatibility, bioactivity, high strength to weight ratio, long life, corrosion & wear resistance, and tailor-ability. Herein, we composed a systematic focus review on the role of nanoparticles in the form of composite materials for the advancements in orthopedic implants. Several nano materials-based reinforcements have been reviewed with various matrix materials, including metals, alloys, ceramics, composites, and polymers for biomedical implant applications. Moreover, the improved biological properties, mechanical properties, and other functionalities like infection resistance, drug delivery at the target, sensing, and detection of bone diseases, and corrosion & wear resistance are elaborated. At last, a particular focus has been given to the un-resolved challenges in orthopedic implant development.

Computational Design for the Damping Characteristics of Poly(ether ether ketone)

To investigate the damping characteristics of poly(ether ether ketone) (PEEK), various potential modifications of the molecular structure, including sulfonate groups, hydroxyl groups, amino groups, carboxyl groups, methyl groups, fluorines, and benzene rings, were considered. It was found that these functional groups can mediate both the storage and loss modulus of PEEK derivatives, and the loss factors of PEEK derivatives are sensitive to the content and type of functional groups, indicating an ideal designability of energy dissipation performance. The reciprocating process of H-bonds and C_π-H bonds breaking and reforming during material deformation and the available free volume in the material are critical to the energy dissipation capacities in polymers.

Incorporation of molybdenum disulfide into polyetheretherketone creating biocomposites with improved mechanical, tribological performances and cytocompatibility for artificial joints applications

To improve mechanical, tribological and biological performances of polyetheretherketone (PEEK) for artificial joints applications, molybdenum disulfide (MoS₂, MS) nanosheets were incorporated into PEEK to fabricate MS/PEEK biocomposites (MPC) with MS content of 4 w% (MPC4) and 8 w% (MPC8). The results revealed that the MS nanosheets with the size of about 400 nm and sheet thickness of about 70 nm were distributed into PEEK matrix, and surface roughness as well as hydrophilicity of MPC increased with the MS content increasing. Moreover, the compressive strength and shore hardness of the MPC were accordingly enhanced. Furthermore, the coefficient of friction of the MPC decreased while the wear resistance of the MPC increased with the MS content increasing in both water-sliding and dry-sliding contact. In addition, rat bone marrow derived stromal cells adhered and proliferated on the composites, indicating that the MPC had no adverse influences on cell behaviors, indicating good cytocompatibility. The results demonstrated that incorporation of MS nanosheets into PEEK produced biocomposites with improved mechanical, tribological and biological performances. MPC8 with no cytotoxicity would have a great potential for artificial joints applications.