No abstract

This article describes micro‐ and nanostructural, mechanical, and thermal properties of nanocomposites based on polyvinyl chloride (PVC) and graphene nanoplatelets (GNP). The primary objective of this study was to extend restricted application area of PVC due to its low thermal stability and limited mechanical properties. GNP‐filled PVC nanocomposites were prepared (0, 0.1, 0.3, 0.5, and 1.0 wt%) by colloidal blending method and characterized in detail. The highest value of the tensile strength 13.73 MPa (an increase of 58%) and the highest value of microhardness 83.42 MPa (an increase of 82%) were obtained with GNP loading content of 0.5 wt% compared neat PVC. The mechanical properties started to decrease at loading higher than 0.5 wt%; however, the thermal properties continued to increase. The differential scanning calorimetry and Fourier transform infrared analysis results of this nanocomposite confirmed that the increase in glass transition temperature from 34.99°C to 44.36°C and the decrease in the height of functional groups peaks proved to prevented segmental relaxation and intermolecular vibrations of PVC, respectively. Thermogravimetric analysis results were showed that the percentage of carbonaceous residue increased to 15.77% by increasing the GNP content from 0.1 to 0.5 wt%. As a result, the best GNP loading was at 0.5 wt% for PVC/GNP nanocomposites where mechanical and thermal properties of PVC/GNP were both enhanced.

A B S T R A C T

Ultra-high molecular weight polyethylene (UHMWPE) has been broadly utilized in hip and knee artificial implant due to its low friction coefficient, high wear resistance and good biocompatibility. However, some disadvantage properties such as low young's modulus and low load bearing, anti-fatigue capacity limit application areas and wear debris of UHMWPE components cause implant failure. For this reason, reduced graphene oxide (RGO) filler was produced by green synthesis with vitamin C and the influences of RGO filler content on the tribological performance under distilled water lubrication condition were investigated and had been correlated with microstructure. RGO filled UHMWPE biocomposites were fabricated by firstly liquid phase ultrasonic mixing and then hot press molding. The characterization and experiment results revealed that the wear behavior of UHMWPE/RGO biocomposites were not only affected by the lubricant and binder properties of RGO, but also restricted by the content of RGO filler. The RGO filled UHMWPE biocomposites exhibited a lower wear rate and friction coefficient in comparison to the unfilled UHMWPE. The biocomposite with 0.7 wt% of RGO showed good interfacial bonding strength and excellent wear resistance. Furthermore, fatigue wear tracks reduced significantly on the same biocomposite surface. High crystallite size and microhardness value of UHMWPE/RGO-0.7 biocomposite was caused destroy the tribofilm formed on the Al 2 O 3 counterface.

Reduced graphene oxide (RGOC) filler that was green synthesized by vitamin C had been included in the ultrahigh molecular weight polyethylene (UHMWPE) matrix to produce biocomposite possessing improved properties especially against wear. The biocomposites filled with different loading (0.1, 0.3, 1.0, and 2.0 wt%) of RGOC was produced by a method of liquid phase ultrasonic mixing and then hot press molding. The structural analysis results of biocomposites showed that RGOC well‐dispersed in polymer matrix and confirmed that there was interaction between the RGOC‐UHMWPE. The biocomposite containing 2.0 wt% RGOC (UHMWPE/RGOC‐2) gave the maximum microhardness and the value increased by 22. 5% compared with unfilled polymer. At the same RGOC content, the biocomposite had the highest thermal stability with residue content at 2.42%. The wear and friction behavior of biocomposites were carried out in a reciprocating friction testing machine under distilled water lubricating conditions. The UHMWPE/RGOC‐2 biocomposite had the lowest friction coefficient value (0.034) and the wear rate of the biocomposite decreased by 44%, compared with that of unfilled UHMWPE. Furthermore, fatigue wear tracks were significantly reduced. This study suggests the use of this composite that had excellent tribological behavior as biomaterial instead of UHMWPE.