High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates.

Eder H C Ferreira,Guilhermino J M Fechine,Angela Aparecida Vieira,Lúcia Vieira

doi:10.3390/polym13142237

Eder H C Ferreira, Guilhermino J M Fechine + Show 2 more

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https://doi.org/10.3390/polym13142237

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Abstract

Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE-UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a significant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomography, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction coefficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.

Highlights

The mixture becomes even poorer with the addition of 20% Ultra-high-molecular-weight polyethylene (UHMWPE), which further increases the viscosity of the system
The results prove that the addition of multilayer graphene oxide (mGO) to neat high-molecular-weight polyethylene (HMWPE) and the HMWPE-UHMWPE (80/20 wt.%) blend significantly improves the abrasive wear resistance, mainly to 0.1 wt.% of mGO
In view of the results presented, we can conclude that the HMWPE-mGO and HMWPE-UHMWPE (80/20 wt.%)-mGO nanocomposites developed here can be used as alternative materials to UHMWPE as the new materials showed a higher abrasive wear resistance and lower friction coefficient

Summary

Introduction

Ultra-high-molecular-weight polyethylene (UHMWPE) is an engineering polymer that has excellent tribological properties. Its semicrystalline structure and high tie chain density give this polymer a very high abrasive wear resistance and low friction coefficient compared to other polymers [1,2]. UHMWPE is widely found in applications where good tribological performance is required, such as biomedical implants, bearings and gears, coating the surface of dump truck buckets, production belts and feed hoppers [3]. UHMWPE is in contact with materials with high wear resistance and hardness (steel, titanium, glass, sand, ores, etc.) in these applications, which can cause abrasive wear on the UHMWPE, reducing its useful life. The development of new materials with better wear resistance than UHMWPE is quite attractive for several sectors of the industry

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