Lcc Fiber Reinforced ‘Green’ Composites Derived From Raw Plantain Starch
Significant research is being conducted to derive environment-friendly, sustainable and fully biodegradable polymers and composites. These help avoid the environmental pollution created by the conventional non-degradable plastics that end up in landfills. Starch is a yearly renewable plant-based resource that is most abundantly available around the world. Increasing number of scientists have modified starches from potato, corn, rice, etc., to create resins that can replace the more common petroleum based ones. Understanding the gravity of the situation, the major objectives of this research are as follows: 1. To develop a fully 'green' resin using raw plantain starch and banana microfibrils with the help of minimal and green/ food grade chemicals. 2. To study the effects of chemical and mechanical treatments on morphology, orientation, crystallinity and ultimately tensile strength of the inherently strong liquid crystalline cellulose fibers. 3. To devise an easy to scale up method for fabricating advanced 'green' fiber reinforced composites as a contribution to the greener world. On these lines, starch was isolated from raw plantain pulp using alkaline and non-alkaline methods. A comparative study of the processes used and resulting starch contents was carried out. Starch content of above 80% was successfully isolated from the plantain fruit by alkaline steeping method using Sodium bisulfite (NaHSO3), a food grade chemical. The physical and mechanical properties of the obtained starch were characterized and compared with the conventional starches. An environment-friendly cross linker 1,2,3,4-butane tetracarboxylic acid (BTCA) along with a catalyst, Sodium hypophosphite-monohydrate (SHP), was used to crosslink the plantain starch into a thermoset resin. Further, banana stem fibers were harnessed to extract cellulosic microfibrils and used as the reinforcing element to enhance the modulus (stiffness) of the resin and make it truly 'green'. Liquid Crystalline Cellulose fibers were used as fillers to make a fiber reinforced composite using RP starch based resin. These fibers were characterized for their tensile properties, diameter and crystallinity in order obtain control data and device methods to improve them further. The fibers were subjected to physical (tension) and chemical treatments to enhance their mechanical properties and make them high strength. Various parameters like treatment chemical, load value, duration were varied to carry out a deep study of their effect on the mechanical properties of LCC fibers. A gradual increase in the percentage crystallinity and mechanical properties was seen on optimizing each parameter. A dramatic increase compared to the control fibers was obtained in the tensile modulus and strength on testing the Sodium bisulfite treated fibers under tension at optimum parameters. In summary, a convenient and easy to scale up process was developed to obtain a fiber reinforced composite from plantain-based resin using its pulp, banana stem fibers and LCC yarns. The mechanical and physical properties of this starch suggest that it can be used in place of conventional starch based resins. In addition, the developed process allows using large quantities of raw cull plantains and potentially eliminating the waste problem created by excess production as well as damage caused during their harvest and transportation.
M.S., Fiber Science
Master of Science
dissertation or thesis