Characterization, Thermal And Mechanical Properties Of Tropical Plant Fibres

The work deals with systematic evaluation of chemical, morphological, anatomical, thermal and mechanical properties of tropical plant fibres. The TAPPI test standard and Fourier transform infrared (FT-IR) spectroscopy were used to study the chemical composition and spectroscopic properties of plant fibre. The crystallinity was determined using X-ray diffraction (XRD). Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe the morphology and cell wall structure of the fibre. Lignin distribution across cell wall layers was analyzed using scanning electron microscopy coupled with x-ray energy dispersive (SEM-EDX) and Raman spectroscopy. In addition, thermogravimetry analysis (TGA) was used to investigate thermal stability of the fibres. Meanwhile, miniature tensile tester also was used to measure the mechanical properties of fibres. Four different types of plant fibre were chosen which include coconut (COIR), banana pseudo-stem (BPS), pineapple leaf (PALF) and sugarcane bagasse (SCB) fibres for the study. Moisture content in all types of plant fibre studied was in the range between 6-9%. Cellulose content was highest in PALF (70%) while lignin was highest in COIR (28%). Meanwhile, SCB consists of the highest hemicelluloses content (10%) compared to other fibres and ash content was the highest in BPS (2.2%). Crystallinity was calculated by to peak height and deconvulated peak method. However, the results were completely different for these two methods. COIR showed the highest crystallinity (52.0%) by peak height method, whereas it was the highest in PALF (68.3%) when calculated by peak deconvulated method

Regeneration of thermally recycled glass fibre for cost-effective composite recycling : Performance of composites based on PP and Recovered glass fibre

Due to economic and technical reasons, no recycling process for glass fibre composites has been commercialized on a large scale. Thermal recycling processes are promising in terms of potential for commercialization but the reinforcement potential of thermally recycled fibres is too low for the application in composites. In the present study, glass fibres were exposed to elevated temperatures prior to composite processing to imitate a thermal recycling process. The exposure of the fibres to elevated temperatures prior to composite processing caused a significant reduction of the mechanical properties of the composites. The heat treated fibres were regenerated with a post treatment. The regeneration of the glass fibres recovered the mechanical properties of the composites almost completely. Thus, this study shows that composites based on thermally recycled glass fibres have the potential to compete with composites based on ‘new’ glass fibres

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

Analysis of fracture damage in silica optical fibers

Microstructured optical fibres (with a periodic transverse microstructure) are of interest since they offer a simple alternative to controlling the index profile of optical waveguides. Although many types of optical fibres and cables have been developed to meet the needs of communications service providers for longterm performance and reliable operation, the brittle nature, aging and fatigue of these fibres, remains to be the key materials issues. The flaws on the surface of fibres caused by processing (drawing) or subsequent assembling make the situation more complex. In this work, experimental investigation and fracture mechanics analysis have been conducted to understand the fracture behavior of these newly developed optical fibres. The results are believed to be useful for design, fabrication and evaluation of optical fibres for a variety of applications

Bandverbindungen der Dornfortsätze der Wirbelsäule

In the cervical region the fibres of the interspinous and nuchal ligaments pass in an anteroc ranial direction: they act against diminishing of the cervical lordosis. In the thoracic region, longitudinal bundles of fibres connect the tops of the spinous processes; they act against an augmentation of the thoracal kyphosis. Between thoracal kyphosis and lumbal lordosis there is no exact course of the fibres of the interspinous ligts. ("thorakolumbaler "Übergangsbereich"). In the lumbar spine the fibres of the interspinous ligts., being very strong, pass in a posterocranial direction. They have the function of limitation the range of flexion ventrally and of limiting backwards - shifting of the cranial vertebra in dorsal-flexion. In the lumbosacral segment additional fibres, arising from the top of the 5th lumbar spinous process, pass in a posterocaudal direction and interlace with the thoracolumbar fascia , whose fibres form — below the 4 th lumbarvertebra — ascissor - latticed structure. The supraspinous ligt. lies superficially to the thoracolumbar fascia. Its fibres pass several spinous processes. I t ends caudally at the 4th lumbar spinous process

Unidirectional Rotation Neurones in the Optomotor System of the Crab, Carcinus

1. Among the optomotor fibres to the eye muscles in Carcinus a class was found which responds to unidirectional fast rotations around various body axes. All had large signals and are therefore of large diameter. 2. In one set of these fibres which fires especially for rotations around the dorsoventral axis, it could be shown that discharges take place especially during accelerations and that, when a rotation in the null direction is suddenly stopped, a short discharge occurs. The fibres for other axes behave in a similar manner. 3. For rotations around the ventro-dorsal axis, but not for other directions, mediumsized fibres are present which, in contrast to the fast fibres, respond to visual stimulation, as well as to body rotations in darkness, thus combining the input properties of the unidirectional fast rotatory and the unidirectional purely optokinetic small fibres. Their sensitivity to visual input is for low rotation velocities, to body rotations is for high rotation velocities

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

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

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