ABSTRACT
Coconut fibre is extracted from the outer shell of a coconut. The common name, scientific name and plant family of coconut fibre is Coir, Cocos nucifera and Arecaceae (Palm), respectively. There are two types of coconut fibres, brown fibre extracted from matured coconuts and white fibres extracted from immature coconuts. The abundant availability of natural fibre gives attention on the development of natural fibre composites primarily to explore value-added application avenues. The utilization of coir fibre helps reduce environmental waste. Reinforcement with natural fibre in composites has recently gained attention due to low cost, easy availability, low density, acceptable specific properties, ease of separation, enhanced energy recovery, C02 neutrality, biodegradability and recyclable in nature. The aim the study is to produce an epoxy based hybrid coconut/sawdust composite and to determine the mechanical and physical properties of the hybrid composite.
The coir fibre was collected from a local supplied and then extracted from its shell using the manual lay-up method before being treated with Sodium Hydroxide and then allowed to dry under direct sunlight for 48hrs. After allowing the fiber to dry, it was separated into it various mixing variations (short and long fibres) and then mixed with Epoxy (hardener) and sawdust (reinforcement) in its various ratios. The design of experiment was carried out using mini-tab (Minitab17). Minitab is a data analysis software package that is used for data analysis. This enabled us to analyze the data for the sawdust to coir fibre mix ratio for both short and long coir fibre.
The tensile strength of the composite specimen was observed to rise with relative increase in reinforcement composition loading and increase in fiber length. The increase in tensile strength could be due to proper adhesion between the epoxy matrix and the coir fibers and sawdust, which contributes to an already improved tensile strength; this ultimately increases the maximum stress that the composite can withstand. Conversely, the decrease in tensile strength of the composite could be due to poor circulation of the epoxy matrix around each individual coir fiber, leading to reduction in matrix-reinforcement interaction (poor adhesion) thereby reducing the maximum stress that the composite can withstand. In case of short fiber length, tensile strength is less due to the fact that length may not be sufficient enough for proper load distribution. The values for the short fibre is as follow; 0.309, 0.463, 0.541, 0.425, 0.502, 0.579 and 0463. On the other hand, for the composites of longer fiber length, tensile strength increases. The values for the long fibre is as follow; 0.386, 0.579, 0.656, 0.579, 0.618, 0.695 and 0.618. For the compression analysis, it was observed that the specimen with short fiber length had higher compression strength than those having longer fiber length as follows; 97.5, 50, 55, 68.75, 37.5, 62.5, 58.75 for short and 67.5, 35, 40, 50, 21.25, 48.75, 43.75 for long. Compressive strength (CS) decreases with increase in fibre length. This is likely due to a greater degree of compactness between the fibers and sawdust particles.
