Comparison of the Thermal and Electrical Conductivities of Pretreated Kenaf–Polyester Composites

T U Onuegbu,P U N Obianuko ,Jonathan Chigbo Obianuko

doi:10.24018/ejers.2021.6.6.2464

Abstract

Conductivity of a material is an important physical property that determines its suitability or otherwise in all engineering designs and construction. The aim of this study is to determine the effects of two pretreatment methods viz acetylation and permanganate on the thermal and electrical conductivities of pretreated kenaf bast fibres applied in polyester resin. Fully grown kenaf (hibiscus cannabalis) were manually retted from the stalk, washed, and cut into short fibre lengths of about 10 cm. One portion of the fibres was pretreated with 5%pbw NaOH solution before immersing it in glacial acetic acid and then in acetic anhydride. The second was also pretreated with5%pbw of NaOH before being pretreated with 0.125%of KMnO4. The third portion of fibres was untreated to serve as control. The ground fibre was incorporated into ortho unsaturated polyester rand cast with moulds of dumb-belland square shapes. The electrical conductivity of the composites was deduced by measuring the resistance of the composites using the high voltage insulation tester model 3122 and calculating from equations. The thermal conductivities were determined by analytical method. The results show that chemical pretreatments of fibres by acetylation and permanganate methods have no appreciable effect on the thermal conductivities of composites. Further findings show that the acetylated fibre composites have no effect on the electrical conductivities of the composites. The permanganate pretreated fibre composites however increased the electrical conductivities of the composites significantly.

Highlights

Natural fibre composites are increasingly being applied in non-structural application of engineering designs in preference to synthetic fibre composites
A recent study by [7] reported that chemical modification resulted in an increase of 43% in thermal conductivity when compared with untreated fibre-composite
The obvious conclusion drawn from this work is that acetylation of kenaf bast fibres used in p resin to produce composites have no effect on the thermal and electrical conductivities of the resulting composites

Summary

Introduction

Natural fibre composites are increasingly being applied in non-structural application of engineering designs in preference to synthetic fibre composites. Using epoxy and unsaturated polyester resins it has been shown that fibre treatment with silane coupling agent bearing functional group, which was able to react with matrix, enhanced significantly the mechanical strength of the final composite [3]. In another of such studies by [4], acrylic acid was used as the coupling agent while in yet another study [5] MAPP was used as coupling agent in jute. It is important to investigate the effects of these two chemical pretreatment methods on the thermal and electrical conductivities of composites of pretreated kenaf-polyester composites

Objectives

Methods

Findings

Conclusion