Effect of Plant Fibres on the Variability of Cob Materials

Earthen materials have different nature components and present a high variability comparing to conventional materials; researchers try to settle it down for a future normalization as environmentally efficient material. But there is a need in energy to do it, either directly (compaction, organic matter extraction, particle screening to get the best particle size distribution ...) or indirectly by including inefficient materials from an environmental perspective (cement, limestone ...). The aim of this study is to follow the variability problematic of cob materials by comparing and understanding variation level of the hygrothermal characteristics due to fibres nature and fibres content. We found that plant fibres (hemp, flax and hay) act as a stabilizer for dry bulk density; at 1% fibres substitute, hemp fibre composites show the highest coefficient of variation on the thermal properties (6.1% on thermal conductivity, 18.74% on specific heat capacity) but flax fibres show the highest mean values. Increasing hay stalk content induces the spread of the hygrothermal properties inside their range of variaation.

Characterization of continuous Hibiscus sabdariffa fibre reinforced epoxy composites

The influence of fibre orientation on physical, mechanical and dynamic mechanical properties of Hibiscus sabdariffa fibre composites has been studied. The composites with longitudinal (0°), transverse (90°) and inclined (45°) fibre orientation were prepared using the hand layup technique. ASTM standards were used for characterization of continuous Hibiscus sabdariffa fibre composites. The composite with longitudinally placed fibres yields improved mechanical characteristics. The addition of longitudinal (0°) oriented continuous Hibiscus sabdariffa fibres to the epoxy enhances tensile strength by 460%, flexural strength by 160% and impact strength by 603% compared to neat epoxy. The longitudinal (0°) fibre oriented composite offers higher resistance to water absorption and thickness swelling compared to other types of composites. All continuous Hibiscus sabdariffa fibre epoxy composites possess an improved storage modulus than the neat epoxy resin. The glass transition temperature of continuous Hibiscus sabdariffa fibre composites is 8%–31% lower than that of neat epoxy. Scanning electron microscopy (SEM) images confirm the existence of voids in the matrix, fibre pullout and crack propagation near the fibre bundle, which indicates the stress transfer between fibre and matrix is non-uniform.

Optimisation and Scale-up of the Synthesis of Gold Nanoparticle-Wool Fibre Composites

<p>Gold nanoparticles are known for their remarkable optical properties; they exhibit localised surface plasmon resonance bands in the visible region of the electromagnetic spectrum. This has led to their use as luxury dyes for the colouring of wool fibres. Gold is associated with wealth and desire, and as such, gold nanoparticle-wool fibre composites may be fabricated into high-quality garments, apparel, textiles and carpets for international markets. Novel proprietary approaches for the laboratory-scale synthesis of gold nanoparticle-wool fibre composites have previously been developed by Professor James Johnston and Dr Kerstin Lucas. The innovative nanotechnology utilises the affinity of gold for sulfur-containing cystine residues in wool fibres, to attract and bind the gold nanoparticles. One approach involves the absorption of gold ions by wool fibres and the nucleation of gold nanoparticles in-situ. In an alternative method, gold nanoparticle colloids are synthesised ex-situ, and are then used to colour wool fibres. The reaction conditions of the in-situ and ex-situ approaches were optimised with respect to cost-effectiveness and scalability. The gold content of the in-situ composites was minimised, and the range of possible colours widened, via the use of heat and external reducing agents. In the ex-situ process, the formation and stability of the gold nanoparticle colloids was studied, and the reaction conditions of the synthesis were optimised. The rate of uptake of gold nanoparticles to wool was controlled by manipulating the pH, concentration, volume, and wool to liquor ratio of the gold colloids, and by introducing auxiliary agents into the dyeing reactions. A range of chemical treatments and alternative stabilising agents were investigated to improve the washfastness properties of ex-situ gold nanoparticle-wool fibre composites. There are numerous size-controllable syntheses of gold nanoparticle colloids at the laboratory-scale. However, when the process is scaled-up, gold nanoparticle synthesis is no longer trivial. A barrel reactor with a high velocity mixer was utilised to achieve uniform mixing and heating in the synthesis of gold nanoparticle colloids of up to 90 L in volume. The ratios of gold to stabilising agents in the colloidal gold syntheses were optimised to result in more stable and reproducible gold colloids for subsequent dyeing reactions. The uniform colouring of small quantities of wool is easily achieved in the laboratory, but preventing colour variation across a kilogram of wool is a significant challenge. Initial kilogram-scale dyeing reactions in static tank reactors resulted in unevenly coloured gold nanoparticle-wool fibre composites. To overcome this, conventional hank dyeing equipment was used to colour felted merino yarn, in collaboration with the wool dyeing industry. Modified hank dyeing procedures were recreated in the laboratory, and composites with remarkable colour uniformity were produced. Industrial package dyeing reactors were then used to colour fine merino yarn with gold nanoparticle colloids. The uptake of gold nanoparticles was controlled by manipulating the owrates, ow direction and amounts of auxiliary agents that were employed in the dyeing reactions. Based upon the success of the industrial dyeing reactions, novel dyeing reactors were developed for the colouring of hanks of wool fibres and yarns in the laboratory. These reactors utilised rapid dye circulation and pressure to produce gold nanoparticle-wool fibre composites with remarkable colour uniformity. The composites were used to fabricate luxury apparel and carpets for international trade expositions. The pathway from synthesis in the laboratory to pilot-scale production of gold nanoparticle-wool fibre composites is presented. The PhD research was an integral step in the successful commercialisation of this innovative nanotechnology, and will assist in scaling-up the synthesis of metal nanoparticle colloids and nanocomposites in the future.</p>

Optimisation and Scale-up of the Synthesis of Gold Nanoparticle-Wool Fibre Composites

<p>Gold nanoparticles are known for their remarkable optical properties; they exhibit localised surface plasmon resonance bands in the visible region of the electromagnetic spectrum. This has led to their use as luxury dyes for the colouring of wool fibres. Gold is associated with wealth and desire, and as such, gold nanoparticle-wool fibre composites may be fabricated into high-quality garments, apparel, textiles and carpets for international markets. Novel proprietary approaches for the laboratory-scale synthesis of gold nanoparticle-wool fibre composites have previously been developed by Professor James Johnston and Dr Kerstin Lucas. The innovative nanotechnology utilises the affinity of gold for sulfur-containing cystine residues in wool fibres, to attract and bind the gold nanoparticles. One approach involves the absorption of gold ions by wool fibres and the nucleation of gold nanoparticles in-situ. In an alternative method, gold nanoparticle colloids are synthesised ex-situ, and are then used to colour wool fibres. The reaction conditions of the in-situ and ex-situ approaches were optimised with respect to cost-effectiveness and scalability. The gold content of the in-situ composites was minimised, and the range of possible colours widened, via the use of heat and external reducing agents. In the ex-situ process, the formation and stability of the gold nanoparticle colloids was studied, and the reaction conditions of the synthesis were optimised. The rate of uptake of gold nanoparticles to wool was controlled by manipulating the pH, concentration, volume, and wool to liquor ratio of the gold colloids, and by introducing auxiliary agents into the dyeing reactions. A range of chemical treatments and alternative stabilising agents were investigated to improve the washfastness properties of ex-situ gold nanoparticle-wool fibre composites. There are numerous size-controllable syntheses of gold nanoparticle colloids at the laboratory-scale. However, when the process is scaled-up, gold nanoparticle synthesis is no longer trivial. A barrel reactor with a high velocity mixer was utilised to achieve uniform mixing and heating in the synthesis of gold nanoparticle colloids of up to 90 L in volume. The ratios of gold to stabilising agents in the colloidal gold syntheses were optimised to result in more stable and reproducible gold colloids for subsequent dyeing reactions. The uniform colouring of small quantities of wool is easily achieved in the laboratory, but preventing colour variation across a kilogram of wool is a significant challenge. Initial kilogram-scale dyeing reactions in static tank reactors resulted in unevenly coloured gold nanoparticle-wool fibre composites. To overcome this, conventional hank dyeing equipment was used to colour felted merino yarn, in collaboration with the wool dyeing industry. Modified hank dyeing procedures were recreated in the laboratory, and composites with remarkable colour uniformity were produced. Industrial package dyeing reactors were then used to colour fine merino yarn with gold nanoparticle colloids. The uptake of gold nanoparticles was controlled by manipulating the owrates, ow direction and amounts of auxiliary agents that were employed in the dyeing reactions. Based upon the success of the industrial dyeing reactions, novel dyeing reactors were developed for the colouring of hanks of wool fibres and yarns in the laboratory. These reactors utilised rapid dye circulation and pressure to produce gold nanoparticle-wool fibre composites with remarkable colour uniformity. The composites were used to fabricate luxury apparel and carpets for international trade expositions. The pathway from synthesis in the laboratory to pilot-scale production of gold nanoparticle-wool fibre composites is presented. The PhD research was an integral step in the successful commercialisation of this innovative nanotechnology, and will assist in scaling-up the synthesis of metal nanoparticle colloids and nanocomposites in the future.</p>

Exploration of Tensile, Flexural and Chemical Inertness Properties of Sisal Fibre Reinforced Polymer Composites-Surface Analysis

Our Experimentation finds, reaction of fibre external analysis on tensile, flexural and chemical resistance properties were studied for sisal fibre reinforced composites. Fibre surface analysis has done to produce link between fibre and the matrix to improve the mechanical properties. Fibre surface analysis were done by boiled the sisal fibres in different % of NaOH and treated the fibres in different % of NaOH, treated in acetic acid and methanol. Polyester resin have used as the matrix for preparing the composites and these properties for Natural sisal fibre reinforced composites were also studied. From the results it was observed that 25% NaOH boiled sisal fibre reinforced composites have higher tensile, flexural properties than other composites. Natural sisal fibre composites show fewer properties than treated composites. Chemical inertness properties indicate that all sisal fibre reinforced composites are resistance to all chemical agents except carbon tetra chloride.