The effect of interface enhancement on the mechanical properties of fibre-reinforced PA6 matrix composites in material extrusion-based additive manufacturing

Using different fibres and ratios can considerably enhance the mechanical properties of thermoplastic composites, and the fibre-matrix interface plays a crucial role in realizing the effects of reinforcements. This research aims to enhance the fibre-matrix interface using sustainable resources to increase the mechanical properties of composites produced using additive manufacturing. To do this, cellulose nanofibrils (CNF) were used for surface modification of carbon, glass, and hybrid (carbon + glass) fibres used in reinforcements in the PA6 matrix. Samples were produced by 3D printing done through material extrusion (MEX). and the effects of fibre types and ratios, print layer thickness, and interface enhancement between fibre-matrix on mechanical properties were investigated experimentally. Results reveal a 5 to 11% increase in the tensile strength of the carbon fibre-reinforced samples, whereas a 72 to 88% increase was observed for the glass fibre-reinforced samples. Furthermore, the tensile modulus value has been increased 4 times in carbon fibre reinforcement samples that used modified fibre compared to PA6 pure. Finally, different types and ratios of fibres had an impact on the glass transition temperature, but there was little to no change in the melting and crystallization temperatures. Our work highlights the potential of the proposed CNF modification made to the fibres for MEX production to produce parts with higher mechanical properties.