Temperature dependent characterization of optical fibres for distributed temperature sensing in hot geothermal wells

This study was performed in order to select a proper fibre for the application of a distributed temperature sensing system within a hot geothermal well in Iceland. Commercially available high temperature graded index fibres have been tested under in-situ temperature conditions. Experiments have been performed with four different polyimide coated fibres, a fibre with an aluminum coating and a fibre with a gold coating. To select a fibre, the relationship between attenuation, temperature, and time has been analyzed together with SEM micrographs. On the basis of these experiments, polyimide fibres have been chosen for utilisation. Further tests in ambient and inert atmosphere have been conducted with two polyimide coated fibres to set an operating temperature limit for these fibres. SEM micrographs, together with coating colour changes have been used to characterize the high temperature performance of the fibres. A novel cable design has been developed, a deployment strategy has been worked out and a suitable well for deployment has been selected.Comment: PACS: 42.81.Pa, 93.85.Fg, 47.80.Fg, 91.35.Dc, 07.20.Dt, 07.60.V

Effect of Silane coupling agent on mechanical performance of glass fibre

Mechanical performance of commercially manufactured unsized and γ-APS sized boron-free E-glass fibres has been characterised using single fibre tensile test. Both apparent fibre modulus and fibre strength were found to strongly depend on fibre gauge length. The average strength of sized fibres was found 40%-80% higher than unsized fibres at different gauge lengths. Weibull analysis suggested that the failure mode of unsized fibres could be described by unimodal Weibull distribution, whereas the strength distribution of sized fibres appeared to be controlled by two exclusive types of flaw population, type A and B. Comparison of the Weibull plots between unsized and sized fibres revealed that the strength of unsized fibres was likely to be dominated by type A flaws existing on the bare glass surface and type B flaws may be related to the defects on the glass surface coated with silane. This was partially supported by the observation of fractured cross-sectional area using SEM. It was, therefore, proposed that the strength difference between unsized and sized glass fibres may be more reasonably interpreted from the surface protection standpoint as opposed to the flaw healing effect. The results obtained from this work showed that silane coupling agent plays a critical role in the strength retention of commercially manufactured E-glass fibres and the silane effect on the fibre strength is also affected by the change in gauge length of the sample

Characterisation of the mechanical and thermal degradation behaviour of natural fibres for lightweight automotive applications

It is well established that light-weighting of automotive parts leads to reduced carbon emissions over vehicle lifetime. Mineral fibres and fillers have a relatively high density and may require high levels of energy in their production, resulting in a large carbon footprint. Natural fibres have been identified as a potential candidate to substitute mineral fillers in automotive application of thermoplastic matrix composites. This paper focuses on the characterisation of the mechanical and thermal degradation of two types of natural fibres (date palm and coir fibres) as part of an evaluation of their potential for the substitution of high density mineral fillers with more environmentally friendly lower density natural fibre reinforcements

Experimental data about mechanical behaviour during compression tests for various matted fibres

A specific experimental device has been set up to test compressive mechanical behaviour of an assembly of fibres. Simple compression, as well as cyclic loading experiments and relaxation tests were performed. The experimental set up also allows to record the evolution of the mat fibre electrical resistance while testing. Experimental results are presented for a variety of fibrous materials. Despite the very different nature of each of these individual fibres, it appears that the mats exhibit a very similar mechanical behaviour. This common behaviour has been observed during monotonic single compression tests, as well as during cyclic or relaxation experiments. These experimental results are discussed in terms of different parameters such as the intrinsic mechanical properties of individual fibres and moreover the tangle intrinsic parameters (effect of fibre length, effect of geometrical position of fibres in the sample, fibre surface modifications. . .). The influence of the contact points between fibres is discussed in regard of the electric resistivity measurement

Reuse of tyre steel fibres as concrete reinforcement

To attain economically viable and environmentally friendly tyre recycling, it is necessary to develop new applications and products, which will use tyre by-products (especially the steel cord) as raw materials. The authors demonstrate that the steel fibres recovered from used tyres can be used to reinforce concrete elements. This application has a great potential, as it is estimated that more than 500000 t of high-quality steel fibres could be recovered annually from used tyres in the EU alone. This paper presents the work carried out as part of various ongoing projects on the use of steel fibres in concrete construction. The first part of the paper deals with waste management issues, the methods used to recover steel fibres from tyres, and existing applications of used tyres. The second part presents the mechanical behaviour of concrete elements reinforced with these steel fibres and discusses the relevant design and economic issues. It is concluded that the use of these steel fibres in concrete construction will benefit not only the construction industry, but also the producers and recyclers of used tyres

Effect of fibre treatments on interfacial shear strength of hemp fibre reinforced polylactide and unsaturated polyester composites

Surface treatment of hemp fibres was investigated as a means of improving interfacial shear strength (IFSS) of hemp fibre reinforced polylactide (PLA) and unsaturated polyester (UPE) composites. Fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane. A combined treatment using sodium hydroxide and silane was also carried out. IFSS of PLA/hemp fibre samples increased after treatment, except in the case of maleic anhydride treatment. Increased IFSS could be explained by better bonding of PLA with treated fibres and increased PLA transcrystallinity. The highest IFSS was 11.4 MPa which was obtained for the PLA/alkali treated fibre samples. IFSS of UPE/hemp fibre samples increased for all treated fibres. This is believed to be due to the improvement of chemical bonding between the treated fibres and the UPE as supported by FT-IR results. The highest IFSS (20.3 MPa) was found for the combined sodium hydroxide and silane treatment fibre/UPE samples

Formation of porous membranes for drug delivery systems

Highly crystalline porous hollow poly (-lactide) (PLLA) fibres suitable for the delivery of various drugs were obtained using a dry-wet spinning process. The pore structure of the fibres could be regulated by changing the spinning systems and spinning conditions. Using the spinning system PLLA-dioxane-water, fibres with a dense toplayer and a spongy sublayer were obtained. The spinning system PLLA-chloroform/toluene-methanol yielded fibres with a very open porous structure. The membrane formation of the former system probably occurs by liquid-liquid demixing followed by crystallization of the polymer rich phase. In the membrane formation process of the spinning system, PLLA-chloroform/toluene-methanol crystallization probably plays a dominant role. The membrane formation process will be related to basic principles of phase separation. The fibres are suitable for the long term zero order delivery of the contraceptive 3-ketodesogestrel and the short term zero order delivery of the cytostatic agent, cisplatin. The drugs are released by dissolution of the drug crystals in the fibre core followed by diffusion through the membrane structure. Short term release of adriamycin could be obtained through an adsorption-desorption mechanism. The pore structures of the fibres have a large influence on the release rates of the drugs investigated. When fibres with dense toplayers were used, low release rates of drugs were observed whereas fibres with well interconnected pore structures over the fibre wall showed very high release rates

PBO Fibres: from saliling design towards architectural performance

p. 3013-3023PBO fibres, also called "high-performance" polymer fibres, are a group of materials known as "rigid rods". Through this work it is pretended to make some considerations about the use of these new generation fibres. Poly (p-phenylene-2.6-benzobisoxazole)(PBO) is rigid-rod isotropic crystal polymer. PBO fibre is a high performance fibre developed by TOYOBO (Japan) PBO fibre is quite flexible and has very soft handling, in spite of its extremely high mechanical properties. Over the past ten years Future Fibres Company has pioneered the use of PBO for yacht rigging and has proven it to provide remarkable performance and longevity. Their method of producing these PBO cables delivers the lightest, smallest cables available on the market today. The PBO cable is formed by combining the incredible properties of PBO (poly(p-phenylene-2,6- benzobisoxazole)) fibre with the simple yet undeniably reliable process of continuous winding. A PBO cable is dry fibre tightly compacted and does not rely on a resin matrix that, if impacted, can be compromised. The cover of the cable is a vital component and whilst PBO is an excellent material for yacht rigging purposes, due to its extreme strength, low elongation and general robustness it must be protected from sunlight and seawater. Future Fibres has perfected its cover design that comprises a consolidating film, environmental protection layer and a customizable braided cover that can be tailored to suit any specific application. PBO has great potential to be used in construction or rehabilitation applications. At the same time the fibres, following further testing, would open up several design opportunities for high quality architectural projects.Gough, CE.; Pobo Blasco, M.; Ruiz Checa, JR. (2009). PBO Fibres: from saliling design towards architectural performance. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/670

Recycling of carbon fibre composites

A clear case for carbon fibre recovery and reuse exists on environmental grounds due to the high cost and energy use of virgin fibre production. On a specific energy basis, carbon fibres can be recovered at around 10% of the energy required to manufacture virgin fibres but the scale of the recovery process can make a large difference to overall cost effectiveness. This study will describe the technical and economic challenges associated with the recycling of carbon fibres, the state of the art in recycling technologies and the re-use of fibres in high performance composites