Department: Chemical Engineering
Osoka, E. C.
Onukwuli, D. O.
The mechanical properties of Composites formed from three selected natural fiber sources (Empty Plantain Bunch Fiber, Empty Palm Bunch Fiber and Rattan Palm Fiber), mercerized at optimum conditions, with two selected thermosetting resins (Polyester and Epoxy resins) have been modeled. Analytical techniques and algebraic relations that can extend the use of traditional tensile test data for computation of Poisson ratio were presented and validated based on its limiting value. A new approach for analysis of tensile test data using linear-quadratic rational models was also proposed. Optimum conditions for mercerization of Empty Plantain Bunch fiber, Empty Palm Bunch fiber and Rattan Palm fiber are 4wt% NaOH for 120mins, 6wt% NaOH for 90mins and 4wt% NaOH for 120mins respectively. Empty Plantain Bunch fiber responds the most to mercerization and the process is controlled by NaOH concentration. The Modulus of Empty Plantain Bunch fiber increases 50 times to 70GPa, while the Tensile Strength increases 15 times to 860MPa after mercerization at optimum conditions. Composites formed from the fibers and matrices show that Empty Plantain Bunch fiber is quite compatible with Polyester resin, increasing its modulus 5 times, while Rattan Palm fiber produces the best properties with Epoxy resin, increasing its modulus 3 times. Composites from Polyester resin have the best flexural properties, of all the composites studied, but have the least Impact strength, about half the flexural strength obtained when Epoxy resin is used as matrix, for Empty Plantain Bunch fiber and Empty Palm Bunch fiber.Composites from Rattan Palm fibers have relatively equal Impact Strength, the matrix of choice notwithstanding. All Composites formed from Epoxy resin have Impact Strength greater than 20kgfm/cm2, which is about nine times the Impact Strength for mild steel used in auto body parts, with the maximum Impact Strength being for Rattan Palm-Epoxy Composite.The micromechanics models studied did not adequately model the Composite behavior, a newmicromechanics model obtained by modifying the Halpin-tsai equation which gave a better fit was proposed. The Response Surface model is the most appropriate model for this study. Rattan Palm fiber-Polyester Composite can be used as substitute for low carbon steel in auto body parts because of the good Impact Strength, while Empty Plantain Bunch-Polyester Composites will serve better for structural purposes.