Composite of Hevea brasiliensis resin reinforced with coir fibre (Cocos nucifera): manufacturing of footwear

In recent decades, the process of environmental degradation and various ecological environmental issues have prompted scientists to focus more on this problematic area. Environmental issues are moving new projects towards producing and using materials that do not harm the environment and will not accumulate in the environment in the end-of-life phase. In order to preserve the environment, the use of biomass materials such as coir, bagasse, sisal, jute, etc. has been intensified in several manufacturing sectors. Therefore, it is of great importance to understand the physical and other properties of these materials and know their structure to explore new future applications. This has resulted in the creation of increased awareness concerning the use of natural fibre-based materials composites. Today, the use of polymers materials in the construction of new products is highly common. Polymeric materials reinforced with synthetic fibres such as glass, carbon, etc. create the advantages of high stiffness and strength, as well as low density compared to conventional materials. Despite these advantages, the use of synthetic fibre-reinforced polymer composites has a tendency to decline due to high costs, as well as having an adverse environmental impact. In this sense, the area of polymer composites reinforced with natural fibres represents a plausible alternative in the field of engineering materials for design applications. The appreciation of alternative materials embedded in biomass materials as an option to conventional material should allow the generation of products with high quality, aesthetics and productivity and a reduced potential impact of environmental pollution. This study aims to develop a sole and a moccasin male footwear from coir fibre and natural resin. Composite variants were made and analysed to check how they are influenced by different arrangements and concentrations of fibres and resin. The main objectives in this study are the processing, characterisation and analysis of composites to be applied for the manufacturing of shoes, providing support to the design for the development of the shoe. Materials science and engineering will be involved to formulate the processes that can turn natural resources into useful products. Employing concepts of manufacturing engineering together with collaborative design tools have made it possible to develop a concept shoe. The composites are made of natural resin (Hevea brasiliensis L.) and coir fibres (Cocos nucifera L.). The involved composites were performed with by a hand lay-up moulding technique. Coir fibres were used as a tissue without any treatment. The fibres were arranged randomly, posteriorly with parallel orientations to analyse which is the best fibre reorganisation in the composite, i.e. which distribution ensures better resistance to the composite. Strength measurements were carried out to measure the extent of fibre orientation. Tensile modulus, tensile strength and tear strength of the composites were analysed to investigate their performance. The characterisation of the coir fibre and composites were conducted by the following tests: evaluation of the composite structure using a stereomicroscope, tensile testing, optical microscopy, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR). This first part was essential because the coir fibre and the composite developed are not strongly known by academic community in terms of their applications for footwear. The results of the characterisation of coir fibre showed that it does not differ with respect to other coir fibres studied. Coir fibre is considered a poor reinforcing fibre in rubber due to its low strength and lack of physical characteristics, which are essential for a reinforcing fibre. The interfacial adhesion between coir and natural rubber can be improved by treatment of the coir fibres. The addition of the matrix with aligned fibres improved the tensile strength of the composite. Despite the composite presenting inferior features, it is appropriate as a material in the manufacture of soles and footwear. They were developed in accordance with the product design process and product development process with some minor variations during the processes performed. In this context, this research investigates the design possibilities of integration in the creation of a sole and a shoe using the composite developed during the research. It was raised the process of production and development of shoes and soles at the same time, whereby we developed a product for the footwear industry to meet the purpose of creating solutions for waste from coconut husk generated in using commercialisation "in natura" by use of coconut water. Using the design of the tools for manufacturing footwear products, the work adopts creative processes based upon research in the areas of aesthetics, materials, ergonomics and human behaviour as well as scientific research. The project allows the interrelation of design, material technology and engineering to meet the technical prerequisites for functionality, shape, aesthetics and cost.

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