Development of jute fiber-epoxy composite as an alternate to plywood floorboards in shipping containers

Abstract

Container boxes are crucial for freight transport, with plywood being the standard flooring. However, plywood presents several disadvantages, such as moisture damage, pest attacks, the need for expensive barrier coatings, and its environmental impact due to deforesting and heavy weight. This research project aims to develop a composite material from jute fiber and epoxy resin as an alternative to plywood floorboards. Natural fiber-reinforced composites offer minimal environmental impacts, no need for expensive barrier coatings, excellent protection against pests, chemical attacks, water, and moisture, and excellent strength characteristics. This research also aims to explore the feasibility and potential benefits of the jute fiber-reinforced epoxy composites. A systematic study is conducted to investigate the mechanical and physical properties of treated woven jute fiber-reinforced epoxy resin matrix composites. Tensile properties, such as tensile strength and tensile modulus, were evaluated. Composite specimens were fabricated using hand layup techniques, using bi-directional woven jute fabric for better bending and shear strengthening. Here, the fibers were treated with a diluted sodium hydroxide solution. Key properties like flexural, impact energy, abrasion resistance, hardness, and water absorption were studied using different fiber volume fractions. The bending performance was studied using a short-span shear test to determine the load required to break the specimens according to the Institute of International Container Lessors (IICL) performance standard, and the results are compared with the IICL performance criteria for container floorboards and the Chinese standard for plywood container flooring. The impact energy of the composite was estimated using Gardner Impact Tester and Charpy Impact Test, and abrasion resistance was concluded using Taber Abrasion Tester. The density of the wove jute fabric was determined, and the result is compared with the values estimated in the literature. At last, the specific gravity of the composites was also concluded as per ASTM D2395-1. This study has found that the tensile strength of a jute fiber-reinforced composite increased by 39%, and the tensile modulus increased by 18% when treated with 5% NaOH. This improvement is attributed to the enhancement of adhesion between the epoxy resin matrix and treated jute fibers. This discovery led to the production of plywood substitute composites using the fibers treated with a 5% NaOH solution. Composites underwent three-point bending tests, also known as short-span shear tests, to evaluate their flexural properties, which are also called bending properties. The performance standard for the freight container floorboards served as the basis for these tests. This study perceives that increasing the fiber loading by 10% resulted in a 33.6% increase in the load required to break the specimen. A 10% increase in fiber loading resulted in a 20.7% increase in bending strength. When the fiber content increased by 10%, the modulus of bending, also known as flexural modulus, increased by 45%. This study also has revealed that increasing the fiber volume fraction increased the shear strength between the laminate planes of the fabricated composites. It can be concluded that the bending properties enhanced as fiber loading increased without a change in fiber orientation. This is primarily due to the high load of the fibers, which effectively distribute the load and resist bending forces. The Charpy impact test had given more accurate results than the Gardner impact tester. The fiber loading is increased from 25% to 35% of the fiber volume fraction, resulting in a 7% increase in the average impact energy. The composite material’s toughness increases with an increase in fiber volume fraction without changing the fiber orientation. This is due to the fiber’s ability to effectively bear and distribute sudden propagation, thereby increasing the impact load or energy required for fracture. Since a resin matrix covers the surface, increasing fiber loading has no significant effect on the composite material’s abrasion resistance. Therefore, the only way to vary the abrasion resistance is by altering the matrix material. The hardness of the composite slightly increases with an increase in fiber volume fraction, possibly due to the higher stiffness of the jute fiber. Immersion testing showed that woven jute fiber-reinforced epoxy composites have negligible water absorption characteristics. This is due to the epoxy resin forming a robust crosslink network with polyamine hardeners, providing resistance to water diffusion and swelling. The current study reveals that the composite, consisting of about 35% fiber volume fraction, meets the performance standards for plywood floorboards in terms of bending properties. The composite demonstrated a superior barrier effect against water and abrasion compared to plywood floor panels. Therefore, the composite may not require the application of an expensive barrier coating.