Investigation of fibre orientation using SEM micrograph and prediction of mechanical properties through micromechanical modelling

The present study concerns the fabrication of short sisal fibre-reinforced polypropylene (PP/SF) composites by melt mixing with different fibre length (3, 6 and 10 mm) comprising of 70% of matrix PP and 30% of SFs followed by injection moulding. The PP/MA-g-PP/SF composites were prepared with the ratio of 65:5:30 with the optimized fibre length of 6 mm at different mould temperatures (25, 45 and 65°C) in a similar fashion. This work also further extended to study the effect of fibre orientation of the composites by numerical calculation of second-order orientation tensor. To evaluate the fibre orientations PP/MA-g-PP/SF composites at different mould temperatures, scanning electron microscope micrographs were used to estimate the accurate principal directions and two-dimensional fibre orientation distributions through centre coordinates of the elliptical fibre images. Finally, a mathematical model of modified rule of mixture was adopted to compare the predicted tensile strength and modulus with the experimental findings.