Developing recycled carbon fibre reinforced material for sustainable additive manufacturing

This paper explores the compounding of recycled polyethylene terephthalate glycol (rPETG) with recycled carbon fibres (rCF) for use in Sustainable Additive Manufacturing. Different forms of rCFs and weight fractions were added to rPETG to assess the dispersion and thermal properties of the formulations achieved when using a two-stage compounding process. The polymer composite mixture was blended in the chamber at 260°C for 5 mins, cooled down to 230°C for 1 minute prior to extrusion, this process was repeated with the produced filament. Cross-section and in-plane samples were potted, grinded and polished to facilitate optical microscopy of the samples. The resultant micrographs were analysed to evaluate the fibre orientation and fibre area fraction. Differential scanning calorimetry of the samples was also undertaken to investigate the effect of adding the fibres on the glass transition temperature of the corresponding polymer composite.

The primary objective of the work was to create and evaluate polymer composite from recycled materials that could be used with 3D printing as an alternative to composite filament made of virgin materials at a fraction of the material cost without compromising its properties. The results show a high degree of directional conformity between the filament extrusion direction and the fibre orientation. The micrographs also indicate a homogeneous distribution of fibres after the two-stage compounding process. The addition of recycled carbon fibres did not appear to have a significant effect on the glass transition temperature of the polymer composites.