Fibre types and properties

A summary of the most important reinforcing filaments and their properties is presented in Tables 21-2.1. 

Handbook of Biomaterial Properties. Edited by J. Black and G. Hastings. Published in 1998 by Chapman Hall, London. ISBN 0 412 60330 6. 

Mohs gravity Mechanical properties Tensile strength, psixlO (MPa) 6.5 6.5 6.5 

The most common aramid fiber available is the Kevlar 49. These fibers are composed of a highly oriented crystalline polymer and present the highest tensile strength/weight ratio. On the other hand the disadvantages 

Filament Diameter Manufacturing strength Density Modulus 

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In all cases, carbon fibres lead to the highest mechanical performances compared to glass and aramid fibres. Nevertheless, their impact behaviour and price restrict their consumption. Glass fibres yield the cheapest composites but performances are more limited. Table 6.10 compares the properties of the main fibre types and shows some examples of properties for a nylon matrix reinforced with short fibres of the three types. 

Table 13.2 Properties of human muscle fibre types and their capacities for fuel utilisation ...

The manufacturing of component parts and panels from this material occurs at lower temperatures and the resulting parts show a lower shrinkage than those made from synthetic plastics. The mechanical behaviour, however, exhibits some similarities with wood and the measured properties depend strongly on the fibre type and content. The model product loudspeaker box combines an interesting noble wood like design with outstanding acoustic properties. They were injection moulded in different complex shapes at various wall thicknesses. 

Typical properties of two-dimensionally reinforced C/SiC and C/C-SiC composites, fabricated by the isothermal CV1-, gradient CVI-, LPI- and LSI-process, respectively, are shown in Table 1, published by representative manufacturers [9, 35, 42, 43]. The variance of properties depends on the fibre type and on the fibre volume content which is governed by the design of the component and the method of preform manufacture. The given values... 

A new hybrid composite was produced by a combination of synthetic and natural fibres with the same AESO matrix, which offered the low cost of natural fibre with the high strength of synthetic fibre. The resultant properties may vary, depending on the composition of the fibre type and follow a weight fraction rule. It has been observed from SEM micrographs that hemp acrylated epoxidised soybean oil (ESO) composite shows fracture surfaces with a larger number of pull outs than the flax-based composites. 

Thus the mechanical properties of uni-directional laminates are very different from those of random laminates even if the same fibre type and resin type are used in each. A factor of 0.65/0.075 or about eight-fold can be expected. 

The emphasis is on commercial materials and formulations. The reason is that commercial materials are rarely pure materials. A pure homopolymer is a rare species in the real-world materials. To arrive at the desired material s properties, either a copolymer is used, sometimes a blend or a dispersion, or additives or filler materials including rubber particles, carbon black or fibres of various type and make may be added, and are thus commonplace in commercial products. This implies a more complex constitution and morphology than expected for pure polymers. However, obviously, the methods described herein can be applied to pure, unmodified, polymers as well. 

The paper-making properties of all of these fibres are quite different from each other and also from wood. This is mostly due to the differing morphology and to some extent the differing chemistry of the fibre cells. The photomicrograph (Figure 1.2), shows a comparison between various non-woody fibre types. 

Two types of models have been applied to the mechanical strength of paper. The first assumes paper to be a continuous network of hydrogen bonds with no other type of bond contributing to its mechanical properties, and the second describes its mechanical strength in terms of a combination of fibre strength and fibre-to-fibre bonds. 

Table 6.4 displays examples of the mechanical and physical properties of the three most important glass fibre types. 

Pretreatment for fillers. When used as a surface treatment for fillers or reinforcing materials, in which the silane is applied to the filler or fibre before incorporation into a resin matrix, the same factors as for pretreatment primers apply. In addition, the particle size and the absence/presence of water are important, and in a sense this application is only a variation on the former. It should be noted that silane treated fillers may have, or impart, different rheological properties to non-treated fillers, particularly particulates. A major disadvantage of this approach is that a general purpose silane may have to be used by a manufacturer rather than one specifically tailored to the use of a particular resin type and less than optimum properties are likely to be achieved in some cases. 

Metallisation of fibres is not only a physical process determined by absorption capacity of the fibres for the metal and diffusion capacity of the metal in the fibre structure, but also depends on chemical parameters such as chemical structure of the fibres, presence of functional groups, reactivity of the fibre and the metal, oxidation state of the metal and the presence, necessity and reactivity of supporting chemicals (e.g. reducing agent). Therefore, it was necessary first to study metallisation at different types of fibres in order to investigate which structure is most useful for further research. In this respect, viscose, cotton, natural silk and polyacrylonitrile fibres were investigated because of their different structure and properties and their availability in the New Independent States of the former Soviet Union (Uzbekistan, Kazakhstan, Kyrgyzstan). 

Regardless of their fibre composition and the type of the manufactured item, cloths for waterproof clothing should have a high and stable hydrophobicity, at the same time preserving their hygienic properties, wear resistance, form stability and attractive appearance. 

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