Abrasive Wear Behavior of CNT-Filled Unidirectional Kenaf–Epoxy Composites

Napisah Sapiai,Mohammad Jawaid,Carlo Santulli,Aidah Jumahat

doi:10.3390/pr9010128

Abstract

Kenaf (Hibiscus Cannabinus) fibers have received significant attention for replacing the usage of synthetic fibers, especially glass fiber, in the fabrication of fiber-reinforced polymer (FRP) composites. The aim of this research was to study the change in wear behavior of kenaf-epoxy fiber composites by filling them with multiwall carbon nanotubes (MWCNT). In particular, the effect of untreated MWCNT (PMWCNT), acid-treated MWCNT (AMWCNT), and silane-treated MWCNT (SMWCNT) was studied, using three different MWCNT loadings, i.e., 0.5, 0.75, and 1 wt.%. The abrasive wear test was conducted to measure the wear properties of the composites. A thermal infrared camera was also used to measure the punctual contact temperature during the abrasive wear test, while the abraded surfaces were analyzed using the stereomicroscope. Starting from the considerable reduction of wear rate with the introduction of kenaf fibers, it was observed that PMWCNT provided some further, yet modest, reduction of wear rate only at the higher loadings. In contrast, the inclusion of AMWCNT proved to increase the specific wear rate of the epoxy-kenaf composites, an effect worsened at higher loadings. This may be due to the weakened interfacial bonding between the AMWCNT and epoxy. On the other hand, the presence of SMWCNT improved the interfacial bonding between CNT and epoxy, as shown by an increase in contact temperature. However, the increase in bonding strength was stipulated to have caused the rougher worn debris, thus inducing a three-body abrasive wear effect.

Highlights

Wear is defined as the loss of materials when being exposed to another moving object
It was believed that PMWCNT’s relatively easy sedimentation was due to agglomerated structures of PWMCNT, whereas acid-treated MWCNT (AMWCNT) and silane-treated MWCNT (SMWCNT) were more stabled and had maintained their dispersion in ethanol even after 72 h. This suggests that the structure of Processes 2021, 9, x FOR PEER REVIEWPMWCNT was slightly altered after acid and silane treatments
The inclusion of the PMWCNT into the composites showed improvement in the wear rates, though not in a consistent way, probably due to uneven distribution of the reinforcement, though the situation slightly improved with higher loadings

Summary

Introduction

Wear is defined as the loss of materials when being exposed to another moving object. Wear is one of the principal objectives of tribology, i.e., the study of the surface behavior of a material when interacting with another moving body, among others like friction and lubrication. The potential of polymer matrix composite (PMC), when used as a substitute in wear applications for existing materials has been explored quite extensively throughout the years. PMCs provide many advantages, such as being relatively cheap, having a high strength-to-weight ratio, and, especially if the reinforcement is formed by plant fibers, a higher environmental friendliness compared to non-renewable sources like metals. In order for the polymer to have the properties at par to metals, some enhancements need to be done. Various types of fibers and reinforcement particles are being incorporated into the polymer matrix to improve the properties of polymers [1,2,3,4,5,6,7]

Objectives

Methods

Results

Conclusion