Mechanical, Thermal and Physical Properties of Hybrid Banana-Jute Fibers Reinforced Epoxy and Polyester Composites: Modeling and Experiments

Abstract

During the last few years, natural fiber reinforced polymer composites are widely used due to their advantages such as ease of fabrication, low density, biodegradability, low thermal conductivity, renewability, nontoxicity, combustibility and low cost of production. Prediction of mechanical and thermal properties of fiber reinforced polymer hybrid composites is a challenging task for current simulation techniques, so does the need to understand the numerical simulation of such materials. The present work reports the analytical, numerical and experimental study on mechanical and thermal behaviour of fiber reinforced polymer hybrid composites. Banana and jute fibers in unidirectional and short form are considered as reinforcement with different fiber loading (0-40 wt.%) and with different weight ratio (1:1, 1:3, and 3:1). Two theoretical models were developed based on one dimensional heat conduction model for calculating the thermal conductivity of unidirectional and short fiber reinforced hybrid composites. The three-dimensional micromechanical models based on finite element method with representative volume element are employed to predict the elastic and thermal conductivity of unidirectional and short banana-jute fiber reinforced polymer hybrid composites. The experimental work presents the test results in regard to the physical, mechanical and thermal behaviour of the epoxy and polyester based composites reinforced with unidirectional and short fibers. Finally, this work includes the comparison of the micromechanical models with experimental and existing analytical formulations like rule of hybrid mixture, geometric mean, Halpin-Tsai, and Lewis and Nielsen models that are used extensively in material modeling. For unidirectional fiber based composites, with addition of 7.5 wt.% banana and 22.5 wt.% jute fiber as reinforcement, the longitudinal tensile strength of epoxy increases from 32.28 MPa to 84.48 MPa and that of polyester increases from 20.72 MPa to 66.89 MPa and the ILSS of epoxy increases from 6.92 MPa to 20.53 MPa and that of polyester increases from 4.05 MPa to 16.16 MPa with same fiber loading. For short fiber based composites, with the addition of 7.5 wt.% banana and 22.5 wt.% jute as reinforcement, the tensile strength of epoxy increased by 103% and reaches 65.84 MPa, flexural strength of epoxy increased by 146% and reaches to 114.31 MPa and its flexural modulus increased by 120% and reaches to 7.33 GPa. Whereas, in polyester based hybrid composites with similar fiber loading, the tensile strength of polyester increased by 171% and reaches to 56.25 MPa, flexural strength of polyester increased by 98.9% and reaches to 81.93 MPa and its flexural modulus increased by 91.39% and reaches to 3.09 GPa. For unidirectional fiber based composites, with the incorporation of 10 wt.% banana and 30 wt.% jute fiber, the longitudinal thermal conductivity of neat epoxy reduced by 32.23% and reaches to 0.246 W/m-K and that of neat polyester reduced by 28.50% and reaches to 0.143 W/m-K. For short fiber based composites at the same fiber loading, the effective thermal conductivity of epoxy reduces from 0.363 W/m-K to 0.239 W/m-K and that of polyester reduces from 0.20 W/m-K to 0.14 W/m-K. The study reveals that the performance of hybrid composites with the weight ratio of banana and jute fiber as 1:3 shows better than the weight ratio of 1:1 and 3:1. With low thermal conductivity and improved mechanical properties, the banana-jute fiber reinforced polymer hybrid composites can be considered in thermal insulation and structural applications in order to reduce the dependence on non-renewable material sources and energy consumption.