Analysis of Natural Fiber Orientation in Polymer Composites Produced by Injection Molding Process

Short fiber reinforced polymer composites (SFRPC) produced by injection molding process have established a commercial utilization in all sectors due to low cost and lower weight of the components. The polymers are reinforced with natural fibers to improve their performance. The orientation of short natural fibers in the polymer composite influences the mechanical performance. This research thus focused on the prediction of natural fiber orientation using a theoretical model and then studied the mechanical properties of natural fiber reinforced composites. The theoretical model was derived by incorporating the shape factor of natural fibers into the angular velocity of the fluid element in order to predict the orientation during the injection molding process. The ANSYS- FLUENT software was used to find the velocity distribution in the fluid domain, from which the angular velocity of the fluid element and the orientation angle were found numerically. This numerical orientation result was then compared to the experimental data. The orientation angle of rigid particles rotating at a fixed distance from the inlet gate was measured by an experimental method where a transparent cavity was filled through an injection molding process An experimental setup was developed to study the orientation behavior of short natural fibers in the flowing viscous fluid. Two experimental case studies were conducted to validate the orientation angles of natural fibers using the derived equation. The case study was performed in two molds with one of varying section, and another wide area section and the experimental orientation angles were compared with the numerical predictions. The numerical results of the flow front and velocity distribution obtained from simulation software were compared with digitized images of the flow front from the experimental method. The natural fibers have improved the strength and modulus of the composites. The composite specimens were produced for different compositions of sisal fiber using compression-molding process and the mechanical properties of the composites were studied. An increase in tensile strength, tear strength, and improved hardness was observed in sisal fiber composites. The morphological study using X-ray tomography and Scanning electron microscopy (SEM) has shown the defects, and the fiber orientation. Short fiber reinforced polymer composites (SFRPC) produced by injection molding process have established a commercial utilization in all sectors due to low cost and lower weight of the components. The polymers are reinforced with natural fibers to improve their performance. The orientation of short natural fibers in the polymer composite influences the mechanical performance. This research thus focused on the prediction of natural fiber orientation using a theoretical model and then studied the mechanical properties of natural fiber reinforced composites. The theoretical model was derived by incorporating the shape factor of natural fibers into the angular velocity of the fluid element in order to predict the orientation during the injection molding process. The ANSYS- FLUENT software was used to find the velocity distribution in the fluid domain, from which the angular velocity of the fluid element and the orientation angle were found numerically. This numerical orientation result was then compared to the experimental data. The orientation angle of rigid particles rotating at a fixed distance from the inlet gate was measured by an experimental method where a transparent cavity was filled through an injection molding process An experimental setup was developed to study the orientation behavior of short natural fibers in the flowing viscous fluid. Two experimental case studies were conducted to validate the orientation angles of natural fibers using the derived equation. The case study was performed in two molds with one of varying section, and another wide area section and the experimental orientation angles were compared with the numerical predictions. The numerical results of the flow front and velocity distribution obtained from simulation software were compared with digitized images of the flow front from the experimental method. The natural fibers have improved the strength and modulus of the composites. The composite specimens were produced for different compositions of sisal fiber using compression-molding process and the mechanical properties of the composites were studied. An increase in tensile strength, tear strength, and improved hardness was observed in sisal fiber composites. The morphological study using X-ray tomography and Scanning electron microscopy (SEM) has shown the defects, and the fiber orientation.

Keywords: Composites
Mechanical property
Morphology
Natural fiber
Orientation
Polymer flow
Advisor: Mohini, Sain
Sanjay Kumar, Nayak