The tribological properties of Lithium grease specimens with different concentrations of Al₂O₃ nanoparticles were investigated using a pin on disc apparatus under different sliding speeds and normal loads. Results showed that Al₂O₃ nanoparticles enhanced the tribological properties of lithium grease and reduced the COF and wear scar width by approximately 57.9% and 47.5% respectively.

Hip joint collapse is a very common health problem. Many cases need a joint replacement, so nano-polymeric composites are an ideal alternative solution. Due to its mechanical properties and wear resistance, HDPE might be considered a suitable alternative to frictional materials. The current research focuses on using hybrid nanofiller TiO₂ NPs and nano-graphene with various loading compositions to evaluate the best loading amount. The compressive strength, modules of elasticity, and hardness were examined via experiments. The COF and wear resistance were evaluated via a pin-on-disk tribometer. The worn surfaces were analyzed based on 3D topography and SEM images. The HDPE samples with various compositions of 0.5%, 1.0%, 1.5%, and 2.0 wt.% filling content of TiO₂ NPs and Gr (with a ratio of 1:1) were analyzed. Results revealed that hybrid nanofiller with a composition of 1.5 wt.% exhibits superior mechanical properties compared to other filling compositions. Moreover, the COF and wear rate decreased by 27.5% and 36.3%, respectively.

The efficient utilization of rice waste has the potential to significantly contribute to environmental sustainability by minimizing the waste impact on the environment. Through repurposing such waste, novel materials can be developed for various biomedical applications. This approach not only mitigates waste, but it also promotes the adoption of sustainable materials within the industry. In this research, rice-straw-derived nanofibers (RSNFs) were utilized as a reinforcement material for high-density polyethylene (HDPE). The rice-straw-derived nanofibers were incorporated at different concentrations (1, 2, 3, and 4 wt.%) into the HDPE. The composites were fabricated using twin-screw extrusion (to ensure homogenous distribution) and the injection-molding process (to crease the test samples). Then, the mechanical strengths and frictional performances of the bio-composites were assessed. Different characterization techniques were utilized to investigate the morphology of the RSNFs. Thermal analyses (TGA/DTG/DSC), the contact angle, and XRD were utilized to study the performances of the HDPE/RSNF composites. The study findings demonstrated that the addition of RSNFs as a reinforcement to the HDPE improved the hydrophilicity, strength, hardness, and wear resistance of the proposed bio-composites.

In this study, the mechanical and tribological properties of polymethyl methacrylate (PMMA)-based dentures strengthened by a low content of alumina (Al2O3) nanoparticles were evaluated. PMMA nanocomposites with different weight fractions (0.2, 0.4, 0.6, 0.8, and 1 wt%) of Al2O3 were fabricated, and a sample of pure PMMA was used as a control. Compression, hardness, and wear tests were conducted to investigate the effect of a low Al2O3 filler content on the mechanical and tribological properties of PMMA. The addition of Al2O3 filler improved the mechanical and tribological characteristics of PMMA. The highest elastic modulus and compressive yield strength (3.56 GPa and 138.21 MPa, respectively) were obtained using the PMMA sample with 0.6 wt% of nanoalumina, which represent an increase of 20.27% and 14.7%, respectively, compared with those of the pure PMMA. The fracture toughness and hardness were improved with the increase in the filler content until it reached 0.8 and 1.00 wt%, respectively. The tribological characteristics of PMMA also improved with the addition of Al2O3 nanoparticles. The least coefficient of friction (COF) and wear rate were obtained at a filler content of 0.6 wt%. Therefore, the addition of low amounts of Al2O3 to PMMA-based resins can improve their mechanical and tribological properties such as hardness, elastic modulus, fracture toughness, COF, and wear resistance.

Hip joint fractures are a serious and prevalent health concern, especially among the elderly. The forces that the lower limbs must withstand are quite strong and can exceed many times the person body weight, especially in the femur. The selection of materials for joint replacements depends heavily on mechanical and tribological properties like strength, hardness, and wear rate. HDPE has been effective as an external prosthetic foot, but its mechanical and tribological constraints have made it difficult to employ as a part of an artificial implant. In this study, an Adaptive Neuro-Fuzzy Inference System (ANFIS) models are utilized to forecast HDPE nanocomposites mechanical and tribological characteristics. The model incorporates various weight fractions of graphene and relies on data obtained from experimental tests. These nanocomposites are prepared with various compositions, and their structure and morphology are evaluated using physiochemical characterization. Compared to pure HDPE, adding graphene enhanced the hardness, strength, and elastic modulus of the HDPE. The nanocomposite with a composition of 2 wt.% graphene showed better mechanical properties compared with pure HDPE. In addition, a finite element model is created to simulate the hip joint and assess the HDPE nanocomposite load-bearing capacity under actual loading. The outcomes of the simulation analysis are consistent with the experiment findings. In addition, in comparison to pure HDPE, the nanocomposite containing 0.5 wt.% graphene showed better tribological performances. Finally, the microscopic examination demonstrated how the additives weight fraction affects the HDPE nanocomposites wear mechanism. Eventually, the ANFIS models proved its ability to predict the tribo-mechanical properties of HDPE nanocomposite with an error that didn’t exceed 3%.

The unique mechanical properties and wear resistance of HDPE give it the potential as an alternative to frictional material. The current research focuses on using hybrid nanoparticles with various loading fillers to determine the best additive contents. The mechanical and tribological characteristics were examined and evaluated. The HDPE nanocomposite samples containing 0.5, 1.0, 1.5, and 2.0 wt.% filling content of Al₂O₃nanoparticles (NPs) and 0.5, and 1.0 wt.% of graphene nanoplatelets (GNPs) were fabricated. The results showed a good enhancement in the mechanical and tribological properties of HDPE composites with the presence of nano additives. The HDPE nanocomposites recorded the best performance with a loading amount of 2.0 wt.% with an equal ratio of hybrid nanofiller Al₂O₃NPs and GNPs.