The effect of laundering on the physical and thermal properties of phase change textile materials
- Authors: Scheepers, Ricardo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Textile chemistry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52038 , vital:43443
- Description: Phase change materials (PCMs) have been incorporated into clothing and textiles to provide added value in terms of thermoregulation and thus added comfort to the wearer in extreme weather conditions and sporting activities. Since clothing is laundered many times during the service life of the textile, the effects of simulated domestic laundering on the physical and thermal properties of a non-woven textile which contains PCMs were investigated. The thermal properties, such as the thermal degradation, melting, evaporation and crystallisation were measured by the TGA and DSC analytical techniques. The physical properties, such as the microcapsule size distribution, and the microcapsule morphologies of the PCM microcapsules, were measured by the SEM and Raman analytical techniques. The main objectives of this study were to determine the effect of repeated laundering at different wash temperatures on the mass loss, enthalpy, and physical changes in PCM. Thermal degradation as determined by TGA thermograms was found to be higher at a wash temperature of 60°C relative to that of a wash temperature at 30°C, the mass loss being 4.6% more at 60°C than at 30°C. This was asserted to physical changes such as size and shape of the PCM microcapsules as evident in SEM images. The SEM images showed broken and collapsed PCM microcapsules in the web and around the fibre, indicating evaporation of the thermoregulating content of the PCM. It was found that the heat capacity of the sample washed at 60°C was much lower than that of the unwashed sample, the difference being approximately 50% in terms of the latent heat capacity as determined by DSC thermograms. This implies that the latent heat effectiveness of the PCM has decreased significantly. The physical properties of the PCM such as the intermolecular interaction, the intensity and width of peaks, polarisation, degree of crystallinity and the orientation changed as illustrated in the Raman analysis. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Reducing the brittleness of poly-furfuryl alcohol resin used in composites
- Authors: Pillay, Princeton
- Date: 2018
- Subjects: Textile chemistry , Textile chemicals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34350 , vital:33339
- Description: The thermoset market is dominated with petroleum-based products. The rising concerns on depletion of non-renewable resources and climate change has motivated researches and industries to find green alternatives for petroleum based materials. The thermoset polymer poly-furfuryl alcohol (PFA) displays good chemical, viscoelastic and moisture stability properties and importantly is bio-based, however, the cured PFA resin is very brittle. The approach of incorporating different types of particulate fillers into the PFA matrix and reinforcing the PFA matrix with flax fabric was used to address the brittleness issue associated with PFA. In the first study, flax fabric was treated with a diammonium phosphate based flame-retardant to reduce the flammability. Compression moulding was used to produce PFA biocomposites and PFA laminates. The effect of the flame-retardant was investigated using Scanning electron microscope (SEM), x-ray diffraction (XRD), fourier transform infrared (FTIR), and cone calorimeter, flexural and tensile tests. The flame-retardant treatment significantly improved the flammability properties, however, decreased the flexural and tensile properties. In the second study, 10 different fillers were selected, these being; ZnO, Clay, montmorillonite (MMT), Rubber, Chitin, Starch, CaCO3, Chitosan, Lignin and TiO2. These fillers were incorporated into the PFA resin at 2% and 5% concentration and reinforced with untreated (UT) flax fabric and flame-retardant (FR) treated flax fabric. Flexural, tensile and izod impact tests were performed on the cured laminates. Thermogravimetric analysis (TGA), SEM and micro x-ray computed tomography scan (CT scan) analysis was performed on selected samples. The inclusion of MMT and Rubber significantly increased the strength and the stiffness of the PFA/UT-Flax laminate while Clay and ZnO reduced the brittleness of the PFA/UT-Flax laminate. FR laminates generally exhibited poor mechanical properties regardless of the type of filler. This was the result of FR damaging the flax fibres during the compression moulding process and hindered the interaction between the PFA matrix and flax fabric. TGA results showed that FR treatment increased the thermal stability of the PFA laminate. SEM and CT scan analysis illustrated the large amount of voids between fabric layers, especially for UT-Flax laminates. The fillers MMT, Rubber and ZnO had a positive effect on the mechanical properties of UT-Flax laminates and therefore were used in the third study. A Box Behnken design of experiment was developed in which the concentration of MMT, Rubber and ZnO was varied between 0 – 5%. Multiple linear regression was used to model the mechanical properties of the PFA/UT-Flax laminates based on a full quadratic model. An optimized filler combination was determined with Solver ®. The experimental results of the optimised PFA/UT-Flax laminate were compared to the values predicted with the statistical model.
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- Date Issued: 2018
Characterisation and optimisation of waterjet impact forces and energy parameters during hydroentanglement
- Authors: Moyo, Doice
- Date: 2012
- Subjects: Textile chemistry , Nonwoven fabrics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10453 , http://hdl.handle.net/10948/d1020134
- Description: Hydroentanglement is an important technique of bonding fibres to produce nonwovens using high velocity waterjets as the primary bonding tool. The work reported in this thesis addresses the gap in scientific knowledge and understanding, both theoretical and experimental, related to the impact forces and energy of the waterjets used in the hydroentanglement process. The current study focused on the impact forces and energy involved in, and the optimisation of, the hydroentanglement process. The results of the experimentally measured waterjet impact forces have been used to characterise the waterjets as well as to verify empirically the theoretical models currently available for explaining the mechanics of the hydroentanglement process. Since the process of supplying pressurised waterjets consumes a great deal of energy, the study of energy consumption and efficiency of the system has been critical. A method was proposed and used to determine the coefficients of velocity and water discharge of an industrial machine set-up, helping explain the mechanism of energy transfer during hydroentanglement and to concurrently optimise the process. Furthermore, a response surface experimental design was used to optimise the hydroentanglement of viscose and Polylactic acid (PLA) fibres into nonwovens. The selected Box-Behnken design, with four factors, namely the waterjet force, machine processing speed, input weight and fibre type, was employed to investigate the multivariate process factors and their interactive effects on physical and mechanical properties of nonwovens. Two sets of experiments, the later for validation, were performed to study the energy transfer efficiency. The results of the relative energy transfer to bond the fibrous web showed that it was possible to produce nonwovens using lower input energy without compromising the quality of the products. The optimum waterjet pressure and machine speed used to produce the Abstract nonwoven with the highest tensile strength for the least amount of energy supplied were identified.
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- Date Issued: 2012
Improving certain high performance properties of natural fibres
- Authors: Chapple, Stephen Anthony
- Date: 2007
- Subjects: Textile chemistry , Fireproofing of fabrics
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10451 , http://hdl.handle.net/10948/815 , Textile chemistry , Fireproofing of fabrics
- Description: Cotton possesses many characteristics that make it desirable to the consumer, and this has resulted in its usage in a broad range of products. Cotton, however, is a flammable material that is easily ignited and rapidly consumed. The flame retardant treatment of cotton is, therefore, an important textile process that has received wide attention over many years. There are a number of commercial flame retardant treatments available for cotton, the most common being phosphate-based. These treatments, however, often have drawbacks or have a negative impact on the desirable properties of the fibre and the challenge still exists for designing better flame retardant products and systems that are durable and have limited impact on fibre properties. The study considers the application of the sol-gel as a coating on fabric that was pre-treated with a phosphate-based flame retardant or as a means for applying a phosphate-based flame retardant. Both treatment methods were found to be suitable for imparting flame resistance to the fabric. The effect of various phosphate-based flame retardants on flammability and fabric properties such as colour, handle and strength was investigated and it was shown that a diammonium phosphate and urea combination gave the best flame resistance. In this regard, a flame resistance was achieved with a lower amount of phosphorous than was used in similar conventional treatments. The durability of the coating to rinsing with water and soaping with a detergent was also investigated. It was found that the flame resistance was lost after rinsing or soaping but the prevention of afterglow combustion was retained. It was shown that the preparatory treatment of the fabric influenced the sol-gel coating process and the flammability of the fabric. Mercerisation and bleaching of the fabric increased the “wet pick-up” during the coating process and improved the flame resistance. The influence of various factors was also investigated in further detail. The ratio of the sol-gel components, the delay after coating prior to drying (hang time) and the curing time were investigated using an experimental design. The curing time and the ratio of components in the sol-gel were shown to have the greatest influence on fabric properties and fabric flammability. It was shown that there is a trade-off between the desired high level of fabric flame resistance and preserving the inherent properties of the fabric such as colour, handle and strength.
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- Date Issued: 2007
An investigation into the properties of cotton fibres as used in nonwoven fabrics
- Authors: Lutseke, Nothando Sazikazi
- Date: 1989
- Subjects: Cotton -- Analysis , Fibers -- Analysis , Nonwoven fabrics -- Analysis , Textile chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4552 , http://hdl.handle.net/10962/d1018241
- Description: The purpose of this investigation was to determine the properties that characterise cotton fibres in the various stages in the CPNF process as well as to determine which fibre characteristics a r e required to entangle the fibres to produce a successful CPNF . The criteria adopted in this work for a successful CPNF include: 1. the tensile strength of the fabrics 2. a well-defined pattern 3. absorbency and wicking The properties selected for investigation were 1. the cotton fibre surface (using SEM and DSC analyses) 2. the degree of degradation of the cotton fibre as a result of the CPNF process (using cellulose fluidity measurements) 3. the non-cellulosic content of the fibre (using IR, DSC, and Chemical analyses) 4. fibre friction 5. absorbency and wicking 6. tensile properties Analysis of the results indicates clearly what the fundamental properties of the cotton fibre must be for a successful cotton CPNF to be manufactured. The conclusions also indicate the necessary properties a man-made fibre must have to produce a successful CPNF.
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- Date Issued: 1989