Development and Characterisation of Novel Biocomposites Fabricated Using Natural Fibres and Rapid Prototyping Technology

Abstract

This research project was motivated by the current development in the field of biocomposites and aims to explore various materials and techniques in the production of environmentally friendly composites. Initially, this study focused on establishing innovative methods of flax reinforcement with different polymeric compounds biodegradable and non-biodegradable based such as poly-lactic acid (PLA), polypropylene (PP), maleic anhydride polypropylene (MAPP) and put them under mechanical testing. One method which was employed here is comingling flax fibres with thermoplastic slivers forming continuous tapes and to be processed via thermal consolidation. Comparisons were made to their woven counterparts based off the tensile and flexural properties achieved by each category. The effects of fibre contents on the mechanical performance have also been evaluated. Similar approach was adopted for reinforcement with thermoset resins as both non-biodegradable unsaturated polyester (UPE) and biodegradable furan poly-furfural acid (PFA) resins were also considered for their development and characterisation. Effect of in-situ temperature on the tensile properties have also been studied for a selection of these biocomposites and their failure mechanisms discussed. A general trend of property decrease with temperature increase was observed as the combination of reinforcement architecture and thermal stability of the matrix control the tensile performance. Another area of focus in this project is the Fused Depostion Modelling (FDM) of PLA parts using readily available 3D-printers. Tensile specimens were built and tested to correlate build parameters to internal configurations. Furthermore, the combined effects of in -situ temperature and filament build orientation have been investigated in terms of constitutive material parameters and final failure mechanism. The investigation involved the evaluation of properties deterioration including tensile strength, modulus, stress at failure, strain-to-failure and energy absorbed. They indicate that the internal structures coupled with in-situ temperature conditioning significantly affect the mechanical behavior of the specimens. The findings of this study are useful in defining the most appropriate raster orientation for FDM components on the basis of their expected in-service loading. Lastly, three designs of lattice cores were proposed to assess the feasibility of using FDM process to produce lightweight polymer-based sandwich panels for structural applications. Effects of the shape topology on the compression in-plane and out of plane, shear and bending strength and stiffness have been experimentally investigated through a full mechanical characterisation. This category of core structures is well suited to compete with high performing honeycomb structures used for aerospace applications.