CARBON FIBRE-REINFORCED

As might be expected from a consideration of the factors discussed in Section 4.2, the imidisation process will stiffen the polymer chain and hence enhance Tg and thus softening points. Hence Vicat softening points (by Procedure B) may be as high as 175°C. The modulus of elasticity is also about 50% greater than that of PMMa at 4300 MPa, whilst with carbon fibre reinforcement this rises to 25 000 MPa. The polymer is clear (90% transparent) and colourless. 

Carbon-fibre-reinforced nylon 6 and nylon 6/12 mixtures have been offered commercially and found use in aerospace md tennis racket applications. 

The markets for polyetherimides arise to an extent from stricter regulations concerning flammability and smoke evolution coupled with such features as high strength, toughness and heat resistance. Application areas include car under-the-bonnet uses, microwave equipment, printed circuit boards and aerospace (including carbon-fibre-reinforced laminated materials). The polymer is also of interest in flim, fibre and wire insulation form. 

In 1997 it was reported that carbon-fibre reinforced PEEK had replaced aluminium in the fuel pump suction manifold of the Airbus. For this application the product has to withstand pressure thrusts of up to 30 bar and resist kerosene at operating temperatures in the range 40-200°C. The ventilation wheel for cooling the electric motor in the same application has also been converted from aluminium to PEEK. 

A large number of grades is available, one supplier alone offering about 40, including unreinforced, glass- and carbon-fibre reinforced, mineral filler reinforced, impact modified, elastomer modified, flame retardant and various combinations of the foregoing. 

It is a popular misconception that plastics are cheap materials. They are not. On a weight basis most plastics are more expensive than steel and only slightly less expensive than aluminium. Prices for plastics can range from about 600 per tonne for polypropylene to about 25,000 per tonne for carbon fibre reinforced PEEK. Table 1.5 compares the costs of a range of plastics. 

GFRP - Glass Fibre Reinforced Plastic KFRP - Kevlar Fibre Reinforced Plastic CFRP - Carbon Fibre Reinforced Plastic... 

GFRP - Glass fibre reinforced plastic KFRP - Kevlar fibre reinforced plastic CRFP - Carbon fibre reinforced plastic... 

A single ply unidirectional carbon fibre reinforced PEEK material has a volume fraction of fibres of 0.58. Use the data given below to calculate the Poisson s Ratio for the composite in the fibre and transverse directions. 

A long sheet of carbon fibre reinforced epoxy is 30 mm wide, 5 mm thick and has a sharp... 

In a short carbon fibre reinforced nylon moulding the volume ffacdon of the fibres is 0.2. Assuming the fibre length is much greater that the critical fibre length, calculate the modulus of the moulding. The modulus values for the fibres and nylon are 230 GN/m and 2.8 GN/m respectively. 

Access of air and water will also affect the corrosion rate. Metal inserts in corrosive plastics are most actively attacked at the plastic/metal/air interfaces with certain metals, notably aluminium titaniumand stainless steel, crevice effects (oxygen shielding and entrapment of water) frequently accelerate attack. Acceleration of corrosion by bimetallic couples between carbon-fibre-reinforced plastics and metals presents a problem in the use of these composites. 

While plastics processing has been of minor importance for today s production of the internal combustion engine and its respective drive system, this sector will become highly relevant if hydrogen is stored on board. A thin-walled aluminium storage sheeted by a carbon-fibre-reinforced plastic has been assumed for the above-shown structural changes in industry. 

Framework of load compensator on plane wings injection moulding of carbon fibre reinforced PEEK replaces the aluminium alloy previously used. This part plays a critical role in plane safety and must resist the static and dynamic stresses and hydraulic fluids. The grade selected after many tests has a high fluidity allowing the manufacture of parts with dimensions of 200 mm by 400 mm. With 30% carbon fibre reinforcement, this PEEK grade ... 

W/m.K for carbon fibre reinforced thermoplastics according to the direction of testing... 

Glass bead filled Carbon fibre reinforced Antistatic ... 

Selfdubricating Carbon fibre reinforced Mica-filled ... 

Some self-lubricating grades of polyphenylene sulphide, containing specific additives and reinforced with glass or carbon fibres, are marketed. The coefficients of friction are good, for example 0.2 for a carbon fibre reinforced compound. 

For a carbon fibre reinforced PEEK, compared to the value at ambient temperature, the percentage retention of tensile or flexural strength or modulus is roughly 20-30% at 250°C. 

Figure 4.105 displays two examples of tensile strength retention versus temperature for a neat and a carbon fibre reinforced polyetherketone, showing the rather fast decay up to 180°C followed by a stabilization. 

For three given grades of neat and glass or carbon fibre reinforced PEEK, Figure 4.107 displays examples of SN or Wohler s curves. 

Figure 4.113 displays three examples of flexural strength retention versus temperature for neat, carbon fibre reinforced and glass fibre reinforced polyamide-imides. The three curves are not distinguishable note the steady decay up to 260°C. 

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