Analysis of the static mechanical properties of zinc oxide nanoparticle coated silk waste reinforced polyester bio- composite.

Abstract

There has been an increasing trend of using natural fibre reinforcements as an alternative to manmade fibre reinforcements for engineered composite applications. Natural fibres are alternative composite reinforcement materials due to their biodegradability, inexpensiveness, abundance and excellent physical properties. This study aimed at analysing the mechanical properties of the fabricated bio-composite from polyester resin reinforced with silk waste fabric. The specific objectives of this work were to characterise physical and mechanical properties of silk waste fabric, fabricate a bio-composite from silk waste fabric treated with zinc oxide nanoparticles and polyester resin and to analyse the static mechanical properties (tensile, flexural, and impact). The silk waste fabric was characterized and the composite fabricated using hand lay-up technique and a mould with dimensions 360x210x4 mm. Central Composite Design was used in the design of experiments and the fibre weight fraction was varied from 11 to 25%. Treatment with nanoparticles was done by soaking silk waste fabric in a 6% concentration of Zinc oxide nanoparticles and 1% citric acid. A sonicator was used to evenly distribute the nanoparticles in the solvent and the fabric was coated using the pad dry cure method. The fabricated composites were cured at room temperature for 24 hours under consolidated pressure of 2.65 kN/m 2 . The mechanical properties of the composites were determined using D790, D638 and D6110 ASTM standards whereas the morphology was investigated using a Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) and the thermal properties evaluated by Thermal Gravimetric Analysis (TGA). The areal density of the silk waste fabric was 76 g/m 2 and its tensile strength was 16.80 MPa. The tensile, flexural and impact strengths of uncoated composites were 27.92 MPa, 52.13 MPa and 32.17 kJ/m 2 respectively. The flexural and tensile strengths of the coated bio-composites increased with increasing fibre weight fraction up to peak values of 32.23 MPa and 53.47 MPa respectively. Bio-composites produced with silk waste fabric treated with nanoparticles had slightly better strengths (tensile 32.23 MPa and flexural 53.47 MPa) compared to bio-composites with non-treated silk waste fabric (tensile 27.92 MPa and flexural 52.13 MPa). The static mechanical properties attained in this study revealed that these bio-composites may be used for non-structural applications for instance partitioning walls and ceiling boards. The study recommended future research works on coating of silk waste fabric with nanoparticles using thermal evaporation technique and analysis of the effect of increasing the number of plies with stacking sequence of angles on mechanical and thermal properties of the composites and morphology.