Publication

Abstract : The dependency of fossil fuel sources for the manufacturing of composites from the artificial fibres and resins warrants the search for alternative renewable sources of raw materials for the composites. Because of the fibres and resins from the renewable source of materials, the cost of the composite materials is going to reduce and also reduces the foreign exchange that is going to be paid towards the procurement of raw materials based on the fossil fuel sources. Comparing to the conventional artificial composite materials, the natural composite materials from the renewable agricultural sources are environment friendly. Even though, there is enough sources for the production of natural fibres and resins from different plant sources, sisal fibres are seems to be better in the terms of cost, availability, strength and the resin synthesized cashew nut shell oil are available in abundant amount in a lower cost with better physico-chemical properties. The goal of the present work is to optimize the strength of sisal fibre by using novolac resin. The sisal fibre has inherent characters of having lots of porous holes connected through lumens. Because of this porous structure, the strength of the fibre is less when compared to artificial fibres and also has higher water absorption tendency when it is subjected to humid environment. In addition to this, the water absorption behaviour associated with chemical nature and porous physical structures results in reduction of strength of the fibres, in turn the strength of the composites. In order to address these issues, the chemical group present in the resin matrices has to be transferred to the internal and external surfaces of the fibre walls. The resin was prepared from the cardanol oil and it is hydrophobic in nature. Because of this hydrophobic behaviour and similar chemical group, the fibres are treated with cardanol oil for different period of time with two different environmental conditions such as hot and cold. The strength of the fibres are measured with single fibre and bunch of fibres mode using Instron and Magisoft UTM fibre testing machine respectively. The raw untreated fibres result in lower strength than the cold and hot environmental conditions treated sisal fibres. Even specifically, the prolonged treatment of sisal fibres in a cold environment yields better strength than the fibres treated in the hot environmental conditions. Further, the water absorption characteristics of cold treated sisal fibres are reduced so drastically to the value of 50% (approx.) from 90% (approx.) for untreated fibres. The hot treated fibres have a less value of water absoption behavior than untreated one, but have a higher water absorption rate than cold treated fibres. The internal structure of the fibres was examined with the help of Scanning Electron Microscope (SEM, Zeiss). Images show variation in the internal structure between the untreated and the cold treated fibres. Because of the treatment with cardanol oil, the non-wetting behaviour of the fibre increased which helps in reducing the water absorption characteristics.