Innovative Biochar-Based Composite Fibres from Recycled Material

Abstract

Carbon materials are becoming crucial in several industrial sectors. The drawbacks of these materials include their high cost and oil-based essence. In recent years, recycled materials have become possible alternative sources of carbon with several advantages. Firstly, the production of this alternative source of carbon may help to reduce biomass disposal, and secondly, it contributes to CO₂ sequestration. The use of carbon derived from recycled materials by a pyrolysis treatment is called biochar. Here, we present composite materials based on different biochar filler contents dispersed in several thermoplastic polymer matrixes. Electrical conductivity and tensile break strength were investigated together with the material characterisation by DTA/TGA, XRD, and scanning electron microscopy (SEM) imaging. Materials with good flexibility and electrical conductivity were obtained. The local ordering in composites resembles both biochar and polymer ordering. The similarity between biochar and carbon nanotubes' (CNTs) XRD patterns may be observed. As biochar is highly cost-effective, the proposed composites could become a valid substitute for CNT composites in various applications.

Keywords: electrical properties; mechanical properties; physical methods of analysis; polymer–matrix composites.

Figure 1

Scanning electron microscope images of (a,b) PMMA-biochar, (c,d) PLA-biochar, (e,f) ABS-biochar, (g,h) EVA-biochar (i,j), TPU-biochar (BC 60%) composites, and (k,l) biochar-derived from recycled cotton fibres.

Figure 2

Stress and strain curves of composite fibres containing various polymers and biochar (BC) as a functional phase. Composites with ABS, PLA, and EVA contained 50% by weight of biochar, while for the TPU-biochar composite, the results for the three percentages of functional phase content are shown: 40%, 50%, and 60%.

Figure 3

DTA (green lines) and TGA (blue lines) measured for biochar composites: (a) ABS-biochar, (b) EVA-biochar, (c) PLA-biochar, (d) PMMA-biochar, and (e) TPU-biochar (60 wt.% biochar).

Figure 4

XRD results of (a) ABS-biochar, (b) EVA-biochar, (c) PLA-biochar, (d) PMMA-biochar (50 wt.% biochar), and (e) TPU-biochar (60 wt.% biochar). Experimental diffractograms are marked with the red line. The grey line depicts the polymer pattern taken from the ICDD database, while the black line being an experimental pattern of biochar.