Fibre properties carbon

Carbon fibre properties depend on the structure of the carbon used and are typically defined as standard, intermediate and high modulus fibres. Several fhousand fibres are twisfed fogether to form a yarn which may be used by itself or woven into a fabric. The yarn or fabric is combined with a resin, usually epoxy, and wound or moulded to shape to form a wide variety of products. 

Trewin EM, Turner RF, Carbon fibres properties and manufacture. Engineering, Apr 1980. 

Mathur RB, Mittal J, Bahl OP, Sandle NK, Characteristics of KMn04 modified PAN fibres, its influence on the resulting carbon fibre properties, Carbon, 32, (1), 71-77, 1994. 

The numerical ratio of X, and X l (degree of anisotropy) increases From a factor of 2 to a factor of 7 in the test range of temperatures. It must be noted that anisotropy of glass-carbon fibre properties has increased markedly against that of carbon and glass fibres. Thus, anisotropy of glass fibre EDT-10 ranges from 1.75... 

Methods of preparation of the laminates depend on the partieular grade of polyimide resin used but in one process the polyimide precursor is dissolved in acetone and this solution is used to impregnate the glass or carbon fibre and thus produce a pre-preg . The pre-preg is dried and then pre-cured at about 200°C for about 3 hours. This operation reduces the volatile content and also modifies the flow properties to make them more suitable for the subsequent... 

Table 18.14 Typical properties of a carbon fibre polyimide laminate...

Some properties of a polyimide carbon fibre laminate are given in Table 18.14. 

Carbon-fibre-filled grades exhibit interesting tribological properties and useful antistatic behaviour. 

Example 3.2 PEEK is to be reinforced with 30% by volume of unidirectional carbon fibres and the properties of the individual materials are given below. Calculate the density, modulus and strength of the composite in the fibre direction. 

Example 3.6 A unidirectional composite consisting of carbon fibres in a PEEK matrix has the fibres aligned at 25° to the loading axis. If the fibres and matrix have the properties indicated below, calculate Ex, Ey, Gxy, Vxy, and Vyx. 

Example 3.8 A thin unidirectional carbon fibre composite is loaded as shown in Fig. 3.14 and has the properties listed below. If the fibres are aligned at 35° to the x-axis, calculate the stresses parallel and perpendicular to the fibres. 

Example 3.13 A single ply of carbon fibre/epoxy composite has the following properties ... 

A unidirectional carbon fibre/PEEK laminate has the stacking sequence [0/35/ — 35]t-. If the properties of the individual plies are... 

The mechanical properties of plastics materials may often be considerably enhanced by embedding fibrous materials in the polymer matrix. Whilst such techniques have been applied to thermoplastics the greatest developents have taken place with the thermosetting plastics. The most common reinforcing materials are glass and cotton fibres but many other materials ranging from paper to carbon fibre are used. The fibres normally have moduli of elasticity substantially greater than shown by the resin so that under tensile stress much of the load is borne by the fibre. The modulus of the composite is intermediate to that of the fibre and that of the resin. 

PTFE, known under the trade names Teflon and Fluon, is resistant to all chemicals, except molten alkalies and fluorine, and can be used at temperatures up to 250°C. It is a relatively weak material, but its mechanical strength can be improved by the addition of fillers (glass and carbon fibres). It is expensive and difficult to fabricate. PTFE is used extensively for gaskets and gland packings. As a coating, it is used to confer non-stick properties to surfaces, such as filter plates. It can also be used as a liner for vessels. 

Specific grades of carbon and steel fibres are especially marketed as additives for conductive plastics allowing resistivities of roughly 10 ohm.cm to be obtained. The other properties of the final material - colour, modulus, impact strength. .. are modified. Carbon fibres have a large reinforcing effect. 

Table 3.16 compares some properties of conductive polypropylenes obtained by adding stainless steel or carbon fibres. 

Table 3.18 shows the effects of several lubricating fillers on the friction properties of polyamides 6 or 66 possibly reinforced with glass or carbon fibres. 

Table 3.19 displays some example properties for polymers filled with ceramic, aluminium or carbon fibre. Note ... 

Intended for high-performance applications because of their cost, carbon fibres have excellent mechanical properties but are sensitive to impact and abrasion. They are used for their attractive characteristics, such as ... 

Enhancement ratios of carbon fibres versus glass fibres. The data used here are the ratios of a property for a carbon fibre reinforced composite (CFRP) versus the same property for the glass fibre reinforced composite (GFRP). 

ISO 10618 2004 Carbon fibre - Determination of tensile properties of resin-impregnated yarn... 

ISO 11566 1996 Carbon fibre - Determination of the tensile properties of single-filament specimens... 

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. 

Boron fibres were used for specific aeronautic composites, for example by Grumman in the wings of the F 14, because of their structural properties. Now, because of their high cost, they are often replaced by carbon fibres. 

Table 6.33 shows the properties of the same thermoplastic (polyamide) reinforced with increasing levels of carbon fibres. 

As already seen, the effect of the carbon fibre content varies depending on the property that is being considered ... 

Table 6.34 shows some basic property examples of short carbon fibre reinforced thermoplastics. 

Some basic property examples of short aramid, glass and carbon fibre reinforced polyamide are shown earlier in Table 6.30. 

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