The hexagonal phase of ZnO NPs was synthesized using sol gel methods and structural properties and correlation with the optical, photoluminescence and antibacterial properties have been investigated.

This manuscript presents an experimental investigation of the friction and wear properties of poly (methyl methacrylate) (PMMA) nanocomposites reinforced with functionalized multi-walled carbon nanotubes (MWCNTs). The aim of this study is to evaluate the potential of MWCNTs as a reinforcement material for enhancing the tribological performance of PMMA. Three types of multi-walled carbon nanotubes, i.e., pristine, hydroxyl functionalized, and carboxyl functionalized, were utilized in this study. The nanocomposite samples were prepared by dispersing varying concentrations of MWCNTs (0.1 wt.%, 0.5 wt.%, and 1 wt.%) within the PMMA matrix via a 3D mixing approach, followed by injection molding/compression molding. The resulting nanocomposite films were characterized using scanning electron microscopy (SEM) to observe the dispersion of MWCNTs within the PMMA matrix. The friction and wear tests were conducted using a pin-on-disk tribometer under dry sliding conditions. The effects of functionalization and MWCNT content on the tribological behaviors of the nanocomposites were analyzed. The nanocomposites exhibited lower friction coefficients and reduced wear rates compared to pure PMMA. The lowest friction coefficient and wear rate were achieved at an optimum MWCNT loading of 0.5 wt.%. It was further revealed that the amount of MWCNT reinforcement, average load, and track diameter significantly affect the coefficient of friction (COF) and rate of wear. The COF and wear rate are best at a filler loading of 0.5 wt.%, a 20 Kg load, and 90 mm. The improved tribological performance of the MWCNT-reinforced PMMA nanocomposites can be attributed to the effective transfer of load between the MWCNTs and the PMMA matrix, as well as the reinforcement effect of the MWCNTs. The MWCNTs acted as reinforcing agents, enhancing the mechanical properties and wear resistance of the nanocomposites.

The incorporation of carboxyl functionalized multi-walled carbon nanotube (MWCNT- COOH) into a polymethyl methacrylate (PMMA) has been investigated. The resultant tensile and flexural mechanical properties have been determined. In this paper, a novel synthesis process for a MWCNT-reinforced polymer nanocomposite is proposed. The proposed method significantly eliminates the most challenging issues of the nano-dispersed phase, including agglomeration and non-homogeneous mixing within a given matrix material, and also resolves the issues occurring in conventional mixing processes. The results of scanning electron microscopy support these claims. This 3D-mixing process is followed by an extrusion process, using a twin-screw extruder for pristine MWCNT, and a compression molding process for COOH-MWCNT, to prepare test specimens for experimentally determining the mechanical properties. The test specimens are fabricated using 0.1, 0.5, and 1.0 wt.% MWCNT, with a remaining PMMA phase. The testing is conducted according to ASTM D3039 and ASTM D7264 standards. Significant improvements of 25.41%, 35.85%, and 31.75% in tensile properties and 18.27%, 48%, and 33.33% in flexural properties for 0.1, 0.5, and 1.0 wt.% COOH-MWCNT in PMMA, respectively, compared to non-functionalized MWCNTs, were demonstrated. The highest strength was recorded for the nanocomposite with 0.5 wt.% f-MWCNT content, indicating the best doping effect at a lower concentration of f-MWCNT. The proposed CNT-PMMA nanocomposite may be found suitable for use as a scaffold material in the domain of bone tissue engineering research. This type of research possesses a high strength requirement, which may be fulfilled using MWCNT. Furthermore, this analysis also shows a significant amount of enhancement in flexural strength, which is clinically required for fabricating denture bases.