Biodegradable Pandanus Utilis fibre-reinforced PLA composites: characterization, mechanical behaviour, and fracture analysis

This study proposes the development of biodegradable composites derived from natural sources to address the issue of waste disposal and high carbon footprint associated with conventionally used composite materials such as carbon fibre reinforced plastics (CFRP) and glass fibre reinforced plastics (GFRP). The fully biodegradable natural fibre reinforced composite (NFRC) was developed by considering fibres from a locally abundant species of Pandanus Utilis and polylactic acid (PLA) as binding matrix. In first part of this study, the chemical characteristics of the biodegradable composites were evaluated via the Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) techniques while water absorption and soil degradability were the physical tests conducted. Mechanical characterization was also conducted to evaluate the flexural and tensile strengths of the composite specimens. While FTIR results revealed a reduction in key chemical constituents in the treated fibres, namely lignin and hemicellulose, DSC results were found to correspond to typical PLA behaviour during thermal heating. The physical test results revealed an increase in the mean percentage of water absorption and mass loss with respect to increase in weight percentage of fibre content. Mechanical test results showed an optimum tensile and flexural performance at a fibre composition of 10 wt. % even though a decrease was observed at higher composition when exposed to sea water. Secondly, the fracture patterns in the biodegradable composites were further investigated by considering the Digital Image Correlation (DIC) method and localized regions of high von-Mises strain distribution were attributed to internal defects. Finally, numerical simulation conducted via the Finite Element Method (FEM) to simulate fracture within the composite specimen showed that exposure to sea water tends to lower its tensile load bearing capacity. The findings of this study can be useful to develop advanced biodegradable composites with high strength-to-weight ratio for a wide range of applications.