Optimisation of PAN-based nanofibres with in situ graphene synthesis and rapid evaluation of graphene-reinforced composites via advanced thermogravimetric analysis

The global transition to a low-carbon economy drives the demand for high-performance materials like carbon fibres, which are essential in industries such as automotive and renewable energy. Polyacrylonitrile (PAN) is the leading precursor in carbon fibre manufacturing because of its high carbon yield and mechanical strength. The performance of carbon fibres is directly determined by the properties of the PAN precursor fibres. However, current production methods do not fully exploit the theoretical mechanical potential of PAN. Enhancing the mechanical performance of PAN fibres by incorporating graphene is promising, but commercial graphene typically exhibits low quality, with high defect densities and multiple layers (>10 layers), with dispersion being an additional challenge. This study addresses these limitations by introducing a novel approach: incorporating in situ synthesised graphene into PAN precursor solutions, achieving a uniform dispersion of 0.21 mg/ml graphene with an average of nine layers. The precursor solution is then used to produce fibres via electrospinning on a drum collector, rotating at approximately 8000 rpm, corresponding to a linear velocity of ∼67 m/s. This process produces uniform, graphene-reinforced fibres with an average diameter of 228 ±45 nm, demonstrating a threefold improvement in stretchability over non-reinforced fibres. Furthermore, advanced thermogravimetric analysis (TGA) is introduced as a rapid evaluation tool for graphene-polymer composites. The advanced TGA of the PANgraphene composite confirms successful graphene integration and identifies a previously unobserved decomposition event at 412 ◦C, specific to shear-exfoliated graphene.