The Potential of Bast Natural Fibres as Reinforcement for Polymeric Composite Materials in Building Applications

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonNatural fibre composites (NFCs), which are polymers reinforced with cellulosic bast fibres, have the potential to be applied into a range of building products. They are seen as an alternative to glass fibre reinforced plastics (GFRP) in some applications, because of natural fibres (NF) relatively high strength and low density. Moreover, natural fibres have a set of beneficial traits, such as thermal insulation, thermal stability, biodegradability, and are inherently renewable. Those characteristics are of importance when NF are used as reinforcements in polymer composites, but developments in mechanical performance, reliability and economic viability are still required in order to be adopted fully by industry. The goal of this thesis was the development of a processing methodology for NFC laminate and subsequent material characterisation to assess the developed material suitability for building applications. Research objectives included materials selection, processing route development for laminates and tubes, manufacture of NFC laminates and analysis of mechanical properties in order to find an optimal composition. Hemp and flax fibres were selected as the reinforcement, because both have high mechanical properties and are important bast fibre crops in the European region with established cultivation and processing methods. As a matrix, fossil-fuel based and partially bio-derived thermoset resin systems were used. Handling and processing methodologies were developed for laminates and composite tubes based on filament winding and compression moulding techniques. The effects of the selected factors, namely material composition, volume fraction, processing parameters, reinforcement linear density, yarn twist, lamination sequence, yarn waviness and hybrid hemp-wool reinforcement were subsequently described in mechanical properties analysis of laminates. The influence of weathering conditions on the mechanical performance of the NFCs was examined. Furthermore, a study of NFC tubes under compression was performed. Results showed that the developed laminates reinforced with NF yarns have sufficient mechanical properties to be utilised in sandwich panels and/or tubes. However, a low resistance to moisture-related weathering restricts the developed NFCs for indoor applications

Novel hybrid flax reinforced supersap composites in automotive applications

Flax fibre bio-epoxy composites have not found many commercial uses in structural applications on account of their lack of cost efficiency and high susceptibility to environmental changes. Non-woven flax mats were subjected to alkali, acetylation, silane and enzymatic treatment, and then combined with untreated unidirectional (UD) flax fabrics to make hybrid flax bio-epoxy composites. Mechanical and environmental resistance (aging) tests were performed on the treated flax fibres. The glass transition temperature was detected at about 75 °C with little effect of treatments. Untreated composites were found to have a tensile strength of 180 MPa while no significant improvement was observed for any of the treatments, which are also not environmentally friendly. The amiopropyltriethoxysilane (APS) composites after Xenon aging, retained the tensile strength of 175 MPa and a modulus of 11.5 GPa, while untreated composites showed 35% reduction in elastic modulus

Review on the Use of Nanofillers in Polyurethane Coating Systems for Different Coating Applications

Polyurethane (PU) is the most common, versatile and researched material in the world. It is widely used in many applications such as medical, automotive and industrial fields. It can be found in products such as furniture, coatings, adhesives, construction materials, Paints, elastomers, insulators, elastic fibres, foams, integral skins, etc. because it has extraordinary properties and the facility to tailor-made various formulations according to property requirement using different raw materials which are available. Though the material is having fascinating properties the material is also associated with various problems such as inferior coating properties. Inorganic pigments and fillers are dispersed in organic components and binders to improve different properties of the coating. This paper is intended to review the various nanofillers used in different PU coating systems. It gives a general introduction about the various fillers and it's classification, Mechanism by which the filler enhances the mechanical properties of the materials, various factors which affect the properties of the coatings. Various methods of incorporation of fillers in the coating systems are discussed. Various nanofillers such as SiO2(Silicon Dioxide), TiO2(Titanium Dioxide), AL2O3(Aluminium Oxide), antimony doped tin oxide (ATO), BaSO4(Barium Sulphate), FE2O3(Ferric Oxide) as well as carbon nanotubes, graphene derived fillers and nano-diamonds are discussed in detail. The importance and effect of surface modification of fillers to enhance coating properties are also discussed along with challenges associated with polyurethane coatings and future trends

The Urban fabric: upcycling textile waste into raw material for urban ground surface design

Landscape surface materials have the opportunity to ground us in our experience and use of materials in the built environment. Surface materials describe the physical textures of the urban areas and include soft and hard landscape solutions, streetscapes, and roads. In modern landscape design, turf, concrete, asphalt, brick or rubber are the most common materials for urban parks or playgrounds. However, the unlimited use of, and lack of awareness about urban landscape surface materials has become a common trend. This “take-make-discard” culture has negatively impacted our environment ecologically, economically, and socially. This thesis study focuses on upcycling textile waste into a recyclable, degradable, and decomposable material for public pavements, especially in public parks and playgrounds. It aims to understand the larger landscape and ecological impacts of existing materials in comparison to a new set of proposed materials, while also revealing the potential opportunities of utilizing circular second-hand material strategies. The material exploration combines research and critique of existing surface materials with an investigation of recycling strategies of textile materials. It then proposes new types of hybrid surface materials that embrace weathering by adding the degradable characteristic of textiles as a new standpoint for thinking about ground surfaces. Ultimately, this research studies the benefits and negative impacts on the environment of public parks from the perspectives offered by this new set of proposed materials, as well as their social interactions and economic conditions

Advantages of lightweight tensioned coated fabrics and foils façades for the building sector

This paper reviews the advantages of lightweight tensioned coated fabrics and foils applied to the existing building sector in order to improve the insulating/shading performance of the external building envelope. The paper describes the main systems developed in the last few years in this field such as pneumatic façades, double curved membrane façades and flat tensioned façades (prefabricated textile panels or tensioned onsite). In addition, the paper analyses the range of foils, coated fabrics and open mesh coated fabrics commonly in use, such as ETFE, Polyester/PVC, Fibreglass/Silicone, Fibreglass/PTFE and ETFE foils

Effects of drycleaning and exposure to light on selected service qualities of two malimo drapery fabrics

Call number: LD2668 .T4 1969 M67Master of Scienc

Strengthening clothing damage analysis: quantification of stabbing force and weathering

Clothing damage analysis is a forensic discipline which provides mainly qualitative evidential value to criminal cases. This two-part investigation strengthens the value of clothing damage analysis through both quantitative and qualitative assessment. The aim of the first study was to determine whether the direction of a weapon (n=6) has any influence on the force required to penetrate a 50:50 polyester/cotton blend fabric. This was carried out at 2 speeds - 100mm/min and 2000mm/min - in a controlled manner using a universal strength tester. Only 2 weapons displayed any distinct differences in forces between some, but not all directions. The variability and overlap of results dictates that caution must be exercised when reporting on the force required to stab fabric. The cut lengths were examined to determine whether stab cuts lengths reflected the weapon width. The cuts were always smaller than the blade width and the bias cuts were always smaller than those in the warp and weft; this was due to the natural stretch which is more pronounced in the bias. The aim of the second study was to discover the evidential value of clothing damage after weathering. Stab cuts were created by different knives (n=2) into the same fabric draped over polystyrene, in the warp and bias directions. The samples were mounted and placed outside for periods of 1, 4 and 8 weeks. The damage was analysed through measurements of the cuts (quantitative), and the identity of the weapon was determined through the cut morphology (qualitative). The stab cuts lengths changed progressively through time, more so in the bias than the warp, but the weapon types remained identifiable. This outcome suggests that the evidential value of clothing after outdoor weathering remains high

Analysis of Fiber UV Degradation Through an Environmental Chamber

Environmentally degraded fibers could impact multiple aspects of a fiber comparison, considering that collected weathered fabrics/fibers may express an altered chemical structure and/or colorimetric property compared to their unexposed counterparts. Depending on the amount of degradation the evidence has suffered, it could be challenging for forensic scientists to make conclusions from their comparative analyses. Observations presented in this study were orchestrated to test the possible outcomes that sunlight has on fabric-based materials. Photodegradation of fabrics was investigated through the use of an environmental chamber for a duration of six weeks, which would be equivalent to three months of real-world UV exposure. Red and blue fabrics of 100% polyester, nylon, and cotton were tested; purity and identity of each sample were confirmed by polarized light microscopy and Fourier-transform infrared spectroscopy. Colorimetric properties were analyzed through fluorescence microscopy. Accelerated weathering was accomplished in an environmental chamber, fabrics were subjected to repeated cycles—two hours at an irradiance of 0.25 w/m2, two hours at 0.47 w/m2, four hours at 0.68 w/m2, two hours at 0.47 w/m2, and lastly two hours at 0.25 w/m2—of UV light (340nm) for 1,008 hours. Relative humidity (\u3c 25%), air temperature (25°C), and black panel temperature (35°C) were programmed to be held constant for the whole duration of the experiment. All exposed fibers either lost all pigment completely or were a faded variation of the original dyed color. Fluorescence microscopic analysis of the blue and red nylon fibers, as well as the red polyester fibers, all revealed substantially varied results between the UV-degraded and their counterparts. In addition, UV-exposed synthetic fibers were found to be more textured, which could have resulted from a reaction between the light and the particles of TiO2 and polymer. This observation should be further studied. Overall, results presented within this study suggest that the UV-exposed fiber would be assumed as a different fiber when compared to its counterpart. Considering that this study mimicked the methods commonly performed by forensic personnel, this conclusion presents a threat for cases with evidentiary fiber samples from both indoor and outdoor conditions.https://scholarscompass.vcu.edu/uresposters/1451/thumbnail.jp

Environmental effects on the durability and the mechanical performance of flax fiber/bio-epoxy composites

The growing usage of bio-composite materials in different engineering applications demands a thorough understanding of their performance during their service. Extreme environmental conditions, such as warm, humid, and freezing environments, among others, can degrade the mechanical properties of the bio-composites when they are exposed to harsh environmental conditions. In addition, the use of these composites in underwater applications can also shorten their life cycle. In this work, the durability and mechanical performance (tensile and flexural behavior)of flax/bio-epoxy composites exposed to different environmental conditions were evaluated. These conditions were chosen to replicate those found outdoors that can affect the durability of these materials: water immersion, warm humid environment and freeze-thaw conditions. Moisture and water absorption behavior were evaluated and the water content (or exposure time)was related to the physical changes and mechanical properties. Results show that the mechanical properties of flax/bio-epoxy composites are clearly degraded by water ageing when they are compared to the ?as manufactured? composites. The tensile strength and modulus is decreased approximately by 9% and 57%, respectively for water saturated (immersed in water until saturation)samples compared to as manufactured samples. On contrary, this reduction rate is only 0.8% and 3%, respectively in case of humidity saturated (exposed to humid environment until saturation)samples. Furthermore, water incurred more severe effects on the flexural properties of the composites, since their flexural strength and modulus is decreased by 64% and 70%, respectively, as compared to as manufactured samples. It was found, however, that these properties can be partially regained after drying the water aged composites. Warm humid environments and freezing-thawing cycles have very little effect on the bio-composites.Fil: Moudood, Abdul. Griffith University; AustraliaFil: Rahman, Anisur. Griffith University; AustraliaFil: Khanlou, Hossein Mohammad. Griffith University; AustraliaFil: Hall, Wayne. Griffith University; AustraliaFil: Öchsner, Andreas. Hochschule Esslingen; AlemaniaFil: Francucci, Gaston Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin