Physically processed waste pineapple leaf fibre for high performance composite with polypropylene

In this work, a new physical method was used to process agro-waste pineapple leaf fibres (PALF) instead of any chemical treatment for fabricating polypropylene (PP) matrix composites. The carding process was used for individualization and partial fibrillation of PALF, as well as for the removal of dust and sticky fibres. The high melt viscosity of PP hinders its penetration into the composite reinforcement. To overcome this difficulty, the separated and fibrillated PALF and PP fibres of different fineness were blended (50% by weight) in the carding process to ensure homogeneous distribution of reinforcement and matrix phases within composites. The blended carded sliver was further parallelized through a gill-drawing process, and subsequently, unidirectional composites were fabricated using the compression moulding technique. The used carding process with an optimum number of passages did not reduce the fibre length or deteriorate the mechanical properties of fibres and was found effective in improving the fibre surface roughness, leading to an improved fibre-matrix interface. The carding process also removed the non-cellulosic materials from PALF, resulting in an increase in the cellulose percentage. The fourth carding passage of the longest PALF led to the removal of non-cellulosic materials by 12 wt%. A homogeneous fibre-matrix distribution was achieved in the case of longer PALF and finer PP fibres, leading to the highest tensile strength, tensile modulus, bending strength, bending modulus, and impact strength of 124.60 MPa, 6.24 GPa, 103.27 MPa, 6.16 GPa, and 104.28 kJ/m² of fabricated composites, respectively. This study is the first to demonstrate the use of carding for the processing of PALF and how PALF length and the carding process influence different properties of fabricated composites.