Shaped fibres

Another novel technique of making oxide fibres is called the inviscid melt technique [24], In principle, any material in a molten state can be drawn into a fibre shape. Organic polymeric fibres such as nylon, aramid, etc., as well as a variety of glasses can be routinely converted into fibrous form by passing a molten material, having an appropriate viscosity, through an orifice. The inviscid (meaning low viscosity) melt technique uses this principle to make oxide fibres. 

Addition of fibre-shaped fillers introduces anisotropy in the material. Characterisation of the thermal expansion properties requires therefore measurements in all three directions. Measurements in the x-, y- and z-direction of a pure, nonfilled material resulted in the following average l.e.c. values at 20°C ... 

The dynamic stiffness (E )/temperature curve in Figure 10.3 shows a strong decrease for temperatures higher than the mesophase transition Tm. This stiffness decrease is sufficient to allow extrusion of this polymer at 285°C. Bxtrusion of a small amount of such a LCP with PP results in LCP particles with a fibre shape in the PP matrix. 

Major applications Available as sheet, rod or tube and fibres. Shaped by thermoforming, casting or extrusion. 

This method does not explicitly contain terms associated with the degree of bonding, fibre spacing, fibre shape, packing geometry and other influential factors which can significantly affect the shear moduli and transverse properties of the lamina. However, as this method is conservative, the actual properties will always be higher than those predicted. 

Figure 4.21 Schematic of the polymer light-emitting electrochemical cell (PLEC) structure with an inset of a powered PLEC. From Zhang Z, Kunping G, Yiming L, Xuey L, Guozhen G, Houpu L, et al. A colour-tunable, weavahle fibre-shaped polymer light-emitting electrochemical cell. Nat. Photonics 2015 9 233-8.

Silva, F.A., Mobasherb, B., Soranakom, C, Filho, R.D.T., 2011. Effect of fibre shape and morphology on interfacial bond and cracking behaviors of sisal fibre cement based composites. Cement Concrete Composites, 33(8), pp. 814-823. 

Jun, Z., H. Q. Hou, J. H. Wendorff, and A. Greiner (2005). Poly(vinyl alcohol) nanofibres by electrospinning influence of molecular weight on fibre shape. e-Polymers 038[2005] l-7. 

The completed formation of a double strand traditionally is indicated optically, preferably by fluorescence measurements. When going from classical methods to chemical sensors, the most important requirement was to inuno-bihze DNA strands at the surface of waveguides, regardless of whether they were planar or fibre shaped. 

Melting the end of the fibre shapes the exit surface of optical fibres. An almost spherical surface will be created by the surface tension of liquid quartz. Its form is determined by the volume of melted quartz, which is equivalent to the amount of absorbed energy. Several techniques have been used to achieve this deformation micro furnace, Bunsen micro-burner, electrical arc and a CO2 laser beam. 

An understanding of the mechanisms responsible for stress transfer provides the basis for prediction of the stress-strain curve of the composite and its mode of fracture (ductile vs. brittle). Such understanding and quantitative prediction may also serve as a basis for developing composites of improved performance through modification of the fibre-matrix interaction. This might be achieved, for example, through changes in the fibre shape, or treatment of the fibre surface. 

Thus, different fibre geometries and fibre-matrix interactions can affect the flexural behaviour of SFRC. This is demonstrated in Figure 7.18 [41], which shows the effects of different fibre shapes on the flexural behaviour of steel fibre shotcrete. These data suggest that the aspect ratio (//d) concept, which was developed for smooth, straight fibres, is not really useful when applied to deformed fibres,... 

Table 10.3 Effect of fibre shape on plastic shrinkage cracking performance in a ring test of 0.57 w/c ratio concrete, after Kovler...

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