Tensile properties of electrospun polyacrylonitrile nanofibres: Influence of fibre orientation and stretching

The tensile mechanical properties of electrospun polyacrylonitrile (PAN) nanofibres are generally lower when compared to melt and solution-spun fibres. Whilst electrospinning has been reported extensively, the effect of stretching of aligned nanofibres has not received significant coverage. In the current study, aligned electrospun PAN nanofibres were produced using the Vee-shield technique. The polymer concentration was 12 wt/vol% in dimethyl sulfoxide (DMSO). The tensile strength and modulus of the aligned PAN nanofibres were 76.31 ± 3.34 MPa and 4.05 ± 1.17 GPa respectively. This represents a threefold increase over the randomly oriented nanofibres (27.8 ± 1.90 MPa, 0.70 ± 0.22 GPa). Post-stretching (13.3% strain, held for 1, 2 and 4 hours) of the aligned nanofibres enhanced the tensile strength by 18.27%. The viscoelastic behaviour of the stretched nanofibres was characterised using the generalised Maxwell model and excellent correlation (R 2 = 0.96) was observed between the experimental and predicted datasets. This paper demonstrates that the mechanical properties of electrospun PAN nanofibres can be enhanced through fibre alignment and controlled post-alignment stretching. This technique offers a method for improving the tensile properties of electrospun nanofibres. • A recently developed electro-spinning technique was used to produce highly aligned polyacrylonitrile (PAN) nano-fibres. • The tensile properties of aligned and randomly oriented PAN nano-fibres were determined where the former was superior. • Stretching the aligned PAN fibres resulted in an increase in the tensile strength and Young’s modulus. • The stress relaxation behaviour of the aligned PAN nano-fibres were modelled and an excellent correlation was observed with the experimentally derived datasets.