Flexural Properties of Wet-Laid Hybrid Nonwoven Recycled Carbon and Flax Fibre Composites in Poly-Lactic Acid Matrix

Barbara Tse,Constantinos Soutis,Hugh Gong,Xueli Yu

doi:10.3390/aerospace5040120

Abstract

Recycling carbon fibre is crucial in the reduction of waste from the increasing use of carbon fibre reinforced composites in industry. The reclaimed fibres, however, are usually short and discontinuous as opposed to the continuous virgin carbon fibre. In this work, short recycled carbon fibres (rCF) were mixed with flax and poly-lactic acid (PLA) fibres acting as the matrix to form nonwoven mats through wet-laying. The mats were compression moulded to produce composites with different ratios of rCF and flax fibre in the PLA matrix. Their flexural behaviour was examined through three-point-bending tests, and their morphological properties were characterised with scanning electron and optical microscopes. Experimental data showed that the flexural properties increased with higher rCF content, with the maximum being a flexural modulus of approximately 14 GPa and flexural strength of 203 MPa with a fibre volume fraction of 75% rCF and 25% flax fibre. The intimate mixing of the fibres contributed to a lesser reduction of flexural properties when increasing the flax fibre content.

Highlights

Carbon fibres (CF) are the preferred reinforcement material for polymer composites because they combine high strength and low weight compared to metallic or ceramic fibres [1]
Recycled CF and flax fibres were used as the reinforcement material, while the poly-lactic acid (PLA) in fibre form was the matrix constituent
Short fibre hybrid composites were manufactured through wet-laying with different ratios of recycled carbon fibres (rCF)

Summary

Introduction

Carbon fibres (CF) are the preferred reinforcement material for polymer composites because they combine high strength and low weight compared to metallic or ceramic fibres [1]. The global demand for CF rose from 33,000 t in 2010 to 72,000 t in 2017 and is expected to grow at a rate of 9–12% for the five years [2]. This increase of CF products comes with the increasing levels of waste resulting from expired prepregs, production cut-offs, testing materials, and end-of-life components from the aeronautics, automotive, and wind industries [3]. Fibre damage and resin residues from the recycling process decreases the fibre tensile strength to around 80% of the virgin fibres, depending on the recycling method, through thermal, mechanical, and chemical recycling treatments [5,6,7]

Methods

Discussion

Conclusion