THE USE OF NON-CONVENTIONAL NATURALCELLULOSIC FIBRES AS REINFORCEMENT FOR UNSATURATED POLYESTER COMPOSITES
THE USE OF NON-CONVENTIONAL NATURALCELLULOSIC FIBRES AS REINFORCEMENT FOR UNSATURATED POLYESTER COMPOSITES
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Date
2015-10
Authors
SABO, AMINU MUSA
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Abstract
This research investigates the use of three natural cellulosic plant fibres in the production of fibre reinforced composite materials. These fibresincluded Dum palm plant, Luffa gourd and Baobab. Different parts of plants were retted in water for seven days to enable fibre extraction. The extraction was carried out with the use of a pointed metal object. The fibres obtained were subsequently dried and then treated with 5% and 20% concentrations of sodium hydroxide at 800C. Breaking load and extension of the bundle of fibres was determined using Instron universal testing machine. Morphology of the fibres was also studied using Scanning Electron Microscope (SEM). Composites were fabricated with the treated and the untreated fibres using unsaturated polyester resin. The properties of the composites; Tensile strength, Impact strength, Bending strength and Hardnesswere determined. Other properties tested include morphology by SEM and Atomic Force Microscope (AFM), Water absorption, Density, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and chemical resistance of the composites. Thermal property by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analyser (TGA) were also determined. The experiment revealed that Dum palm fibres have the highest strength followed by Baobab and then Luffa gourd. The SEM micrographs of the treated fibres suggest that cellulosis, hemicellulosis, pectins and lignin have been removed from the surfaces hence a clean surface is revealed. On the assessment of tensile strength of both untreated and treated fibres, Luffa gourd and Dum palm fibre composites have higher tensile strength than Baobab fibre composite. Impact strength assessment of treated and untreated fibres reveals that Baobab composite has the highest impact strength value followed by Luffa gourd and then Dum palm fibre composite. On the assessment of bending modulus, treatment has improved the property in Baobab and Luffa gourd composites, whereas it reduces in Dum palm composite. Moreover, hardness property assessment shows Luffa gourd and Dum palm composites improved with treatment while in Baobab composite, it reduces. In the chemical resistance assessment, all the composites were found to be resistant to some chemicals and not to others. Water absorption assessment shows no significant effect on all the composites, with low values. The densities of the composites were found to be the same. The FTIR analysis indicates a shift in positions of some peaks after the treatment, this suggest that in the surface of the treated fibre composites there is a change in chemical groups due to alkaline treatment hence a shift in positions as shown in the spectra. Morphological analysis of the composites (by SEM) shows a more uniform distribution of fibres in the matrix of treated fibre composites than the untreated ones. A more uniform distribution of fibres fortreated fibre composites is confirmed by the AFM micrograph compared to untreated fibre composites. Thermal analysis by DSC shows (nearly similar rate of decomposition) for treated and untreated fibre composites. In TGA analysis, (different peaks) were observed for both treated and untreated composites; the different rate of degradation observed between the untreated and treated fibre composites is marginal this may be due to the removal of pectins, lignins and hemicelluloses by the alkali treatment. Lastly, XRD analysis showed untreated samples to be more crystalline than the treated samples; this is because sodium hydroxides have opened the fibres internal structure, leading to better molecular chain re-arrangement. In conclusion, chemical treatment improves the mechanical, physical and thermal properties of the fibre reinforced composites as a result of better cohesion between the reinforcing fibres and the matrix. Therefore, these natural fibre reinforced composites are recommended for light weight engineering applications.
Description
A DISSERTATION SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
IN PARTIAL FULFILMENT FOR THE AWARD
OF DOCTOR OF PHILOSOPHYIN
FIBRE AND POLYMER TECHNOLOGY
DEPARTMENT OF TEXTILE SCIENCE AND TECHNOLOGY
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
USE,, NON-CONVENTIONAL,, NATURALCELLULOSIC FIBRES,, REINFORCEMENT,, UNSATURATED,, POLYESTER,, COMPOSITES.