Isolation, characterization and functionalization of cellulose fibres derived from the waste pineapple leaf fibres by hydrolysis to produce cellulose acetate
- Authors: Seyisi, Thulethu
- Date: 2023-04
- Subjects: Nonwoven fabrics -- Technological innovations , Pineapple fiber -- South Africa , Fibrous composites
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61248 , vital:69844
- Description: This thesis forms part of the Nelson Mandela University biomass and nanotechnology project, which aims at using agricultural waste for many applications, including biomedical applications, water treatment, and agricultural films. Pineapple leaf fiber (PALF) is one of the natural fibers with the highest cellulose content (about 80%), and they produce about 2.5–3.3% of the weight of green leaves. However, the other parts of the pineapple fruit, such as the leaves and crown, are still treated as waste due to a lack of understanding of the benefits and risks of these parts of the pineapple fruit. The transformation of PALF as a renewable and abundantly available natural residue into cellulose fibers (CFs) will reduce the waste accumulated in the atmosphere, and it will add value to the cultivation of pineapple. In the biomedical industry, CF is very promising in terms of drug delivery. Cellulose acetate is a remarkable biomaterial extensively used in biomedical applications due to its properties such as being non-toxic, non-irritant, biodegradable, heat resistant, and less hygroscopic. In this research, the isolation, functionalization, and characterization of cellulose from PALFs were conducted. The PALFs were dried and ground into small particles before being alkali treated with sodium hydroxide to remove the non-cellulosic components. Moreover, the remaining lignin in the residue was removed using sodium chlorite and acetic acid; this process is known as the bleaching process. The bleaching process resulted in white CFs, which was an indication of the successful removal of the non-cellulosic material. The obtained CFs were further functionalized using acetic acid, acetic anhydride, and sulfuric acid, and this reaction is known as the acetylation reaction. Subsequently, both treated, untreated, and functionalized CFs were characterised using the following instruments: FTIR, SEM, SPM, TGA, XRD, and XPS. In the FTIR data of raw PALFs, the following functional groups were more pronounced: C-O, C=C-O, and C=O, whereas peak C-O-C disappeared and peak CH2, C-O, were less pronounced. These FTIR results confirmed the successful removal of non-cellulosic components. The SEM and SPM images visually suggested the partial removal of hemicellulose and lignin from the raw PALFs after the chemical treatment, which are the cementing materials around the fiber bundles. The TGA studies revealed good thermal stability for the isolated CFs from PALFs. The XRD diffractograms of the PALFs showed a cellulose I crystal pattern where the peaks were located at angular positions (2θ) of around 18°, 26°, and 41°. Lastly, after the functionalization of CFs, the cellulose structure remained intact (not damaged); instead, the newly ix introduced functional groups (the acetyl group) were attached at the ends of the cellulose structure. These results are therefore confirmation of the successful removal of non-cellulose material from the PALFs after the chemical treatment. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science and Management, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Seyisi, Thulethu
- Date: 2023-04
- Subjects: Nonwoven fabrics -- Technological innovations , Pineapple fiber -- South Africa , Fibrous composites
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61248 , vital:69844
- Description: This thesis forms part of the Nelson Mandela University biomass and nanotechnology project, which aims at using agricultural waste for many applications, including biomedical applications, water treatment, and agricultural films. Pineapple leaf fiber (PALF) is one of the natural fibers with the highest cellulose content (about 80%), and they produce about 2.5–3.3% of the weight of green leaves. However, the other parts of the pineapple fruit, such as the leaves and crown, are still treated as waste due to a lack of understanding of the benefits and risks of these parts of the pineapple fruit. The transformation of PALF as a renewable and abundantly available natural residue into cellulose fibers (CFs) will reduce the waste accumulated in the atmosphere, and it will add value to the cultivation of pineapple. In the biomedical industry, CF is very promising in terms of drug delivery. Cellulose acetate is a remarkable biomaterial extensively used in biomedical applications due to its properties such as being non-toxic, non-irritant, biodegradable, heat resistant, and less hygroscopic. In this research, the isolation, functionalization, and characterization of cellulose from PALFs were conducted. The PALFs were dried and ground into small particles before being alkali treated with sodium hydroxide to remove the non-cellulosic components. Moreover, the remaining lignin in the residue was removed using sodium chlorite and acetic acid; this process is known as the bleaching process. The bleaching process resulted in white CFs, which was an indication of the successful removal of the non-cellulosic material. The obtained CFs were further functionalized using acetic acid, acetic anhydride, and sulfuric acid, and this reaction is known as the acetylation reaction. Subsequently, both treated, untreated, and functionalized CFs were characterised using the following instruments: FTIR, SEM, SPM, TGA, XRD, and XPS. In the FTIR data of raw PALFs, the following functional groups were more pronounced: C-O, C=C-O, and C=O, whereas peak C-O-C disappeared and peak CH2, C-O, were less pronounced. These FTIR results confirmed the successful removal of non-cellulosic components. The SEM and SPM images visually suggested the partial removal of hemicellulose and lignin from the raw PALFs after the chemical treatment, which are the cementing materials around the fiber bundles. The TGA studies revealed good thermal stability for the isolated CFs from PALFs. The XRD diffractograms of the PALFs showed a cellulose I crystal pattern where the peaks were located at angular positions (2θ) of around 18°, 26°, and 41°. Lastly, after the functionalization of CFs, the cellulose structure remained intact (not damaged); instead, the newly ix introduced functional groups (the acetyl group) were attached at the ends of the cellulose structure. These results are therefore confirmation of the successful removal of non-cellulose material from the PALFs after the chemical treatment. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science and Management, 2023
- Full Text:
- Date Issued: 2023-04
Studies on flax/polypropylene-reinforced composites for automotive applications
- Authors: Biyana, Nobuhle Yvonne
- Date: 2015
- Subjects: Polypropylene fibers , Fibrous composites , Reinforced plastics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10456 , http://hdl.handle.net/10948/d1021150
- Description: The use of natural fibers as reinforcement in thermoplastics presents an interesting alternative for the production of low cost and ecologically friendly composites. One of the advantages of using natural fibres is their low specific weight, resulting in higher specific strength and stiffness when compared to glass reinforced composites. Natural fibres also present safer handling and working conditions. They are non-abrasive to mixing and can contribute to significant cost reduction. This work is divided into two phases: Phase 1 deals with developing nonwoven mats composites from flax/polypropylene (PP) and evaluating their properties. Flax/polypropylene fibres (at different weight ratios) were processed by needle-punching technique in order to form nonwoven mats. The mats were compression-molded at a temperature of 180oC to form composite materials. The mechanical, thermal and viscoelastic properties of the composites were analyzed. Composites (untreated and silane-treated) were also subjected to varying conditions of temperature and humidity and the tensile properties of the conditioned and unconditioned composites were investigated. The mechanical properties (tensile, flexural and impact) of flax/PP composites were found to increase and reach maximum values at 30 per cent fibre loading and then decrease at higher fibre content. Thermal studies revealed that the composites were stable up to 320oC and samples containing 40 per cent flax fibres were found to exhibit greater thermal stability than neat PP. The dynamic mechanical analyses of the composites showed that the incorporation of flax in the composites resulted in an increase of the storage modulus with a maximum value exhibited by composite containing 40 per cent fibre loading. Composites containing chemically modified fibres exhibited low tensile modulus after conditioning. Phase 2 is based on the investigation of the effect of nano-calcium carbonate (CaCO3) on the properties of two types of polymer matrices: recycled PP and virgin PP. In this case, composites were prepared by melt-mixing and injection molding. The mechanical and thermal properties of the composites were characterized. The tensile modulus of the nano-CaCO3 filled PP (virgin and recycled) composites were found to increase and reach maximum at 30 per cent nano-CaCO3 loading, while the tensile strength decreased with increasing filler content. Thermal studies showed that the nano-CaCO3 filled PP samples exhibited a one-step degradation pattern and are thermally stable up to 450oC. The thermal stability of the samples was found to decrease following the addition of nano-CaCO3. SEM micrographs of the tensile fractured surfaces of composites of the nano-CaCO3 filled virgin and recycled PP revealed the presence of nano-CaCO3 agglomeration.
- Full Text:
- Date Issued: 2015
- Authors: Biyana, Nobuhle Yvonne
- Date: 2015
- Subjects: Polypropylene fibers , Fibrous composites , Reinforced plastics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10456 , http://hdl.handle.net/10948/d1021150
- Description: The use of natural fibers as reinforcement in thermoplastics presents an interesting alternative for the production of low cost and ecologically friendly composites. One of the advantages of using natural fibres is their low specific weight, resulting in higher specific strength and stiffness when compared to glass reinforced composites. Natural fibres also present safer handling and working conditions. They are non-abrasive to mixing and can contribute to significant cost reduction. This work is divided into two phases: Phase 1 deals with developing nonwoven mats composites from flax/polypropylene (PP) and evaluating their properties. Flax/polypropylene fibres (at different weight ratios) were processed by needle-punching technique in order to form nonwoven mats. The mats were compression-molded at a temperature of 180oC to form composite materials. The mechanical, thermal and viscoelastic properties of the composites were analyzed. Composites (untreated and silane-treated) were also subjected to varying conditions of temperature and humidity and the tensile properties of the conditioned and unconditioned composites were investigated. The mechanical properties (tensile, flexural and impact) of flax/PP composites were found to increase and reach maximum values at 30 per cent fibre loading and then decrease at higher fibre content. Thermal studies revealed that the composites were stable up to 320oC and samples containing 40 per cent flax fibres were found to exhibit greater thermal stability than neat PP. The dynamic mechanical analyses of the composites showed that the incorporation of flax in the composites resulted in an increase of the storage modulus with a maximum value exhibited by composite containing 40 per cent fibre loading. Composites containing chemically modified fibres exhibited low tensile modulus after conditioning. Phase 2 is based on the investigation of the effect of nano-calcium carbonate (CaCO3) on the properties of two types of polymer matrices: recycled PP and virgin PP. In this case, composites were prepared by melt-mixing and injection molding. The mechanical and thermal properties of the composites were characterized. The tensile modulus of the nano-CaCO3 filled PP (virgin and recycled) composites were found to increase and reach maximum at 30 per cent nano-CaCO3 loading, while the tensile strength decreased with increasing filler content. Thermal studies showed that the nano-CaCO3 filled PP samples exhibited a one-step degradation pattern and are thermally stable up to 450oC. The thermal stability of the samples was found to decrease following the addition of nano-CaCO3. SEM micrographs of the tensile fractured surfaces of composites of the nano-CaCO3 filled virgin and recycled PP revealed the presence of nano-CaCO3 agglomeration.
- Full Text:
- Date Issued: 2015
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