Temperature fibre

Bruce-Black, W., Structure-property relationships in high temperature fibres, Trans. NY Acad. ScL, 32, 765, 1970. 

Figure 5.13 Tensile test of a cross-ply laminate. Variation of strain and specimen temperature. Fibre T300, resin LY 556, MY720 (50 50), lay up [Oj, 9O2, O2, 9021s. Load rate = 6.6Nmm s ...

Short-fibre reinforced ceramic matrix composites can be produced by sintering at high temperatures, similar to ordinary ceramics (see section 7.1). The fibres are mixed with the powder and the composite is sintered at high temperatures. Fibre volume fractions of 35% can be obtained in this way. 

Polymer solutions containing 23 wt% and 24 wt% PPO produced the best hollow fibres in terms of strength and suitability for gas permeation testing. Fibres could not be produced using polymer solutions containing 20 wt% and 25 wt% PPO because of the low viscosity of the former and because the latter starts to gel at room temperature. Fibres produced from polymer solutions containing 22 wt% were found to have poor mechanical strength. 

BE-1432 Fibre optic strain monitoring at elevated temperatures RoH Ouatavaaon Vattenfall AB... 

BE-7S67 Fibre optics for remote monitoring of structural integrity of elevated temperature insulated systems (FORMS) Mr. Manuel Gomea Eitrada Nacional... 

This is also known as Bulk Moulding Compound (BMC). It is blended through a mix of unsaturated polyester resin, crosslinking monomer, catalyst, mineral fillers and short-length fibrous reinforcement materials such as chopped glass fibre, usually in lengths of 6-25 mm. They are all mixed in different proportions to obtain the required electromechanical properties. The mix is processed and cured for a specific time, under a prescribed pressure and temperature, to obtain the DMC. 

As Fig. 20.7 shows, if DS eutectics ( DSEs ) prove successful, they will allow the metal temperature to be increased by =100°C above conventional DS nickel alloys, and the inlet temperature by =200°C (because of a temperature scaling effect caused by the blade cooling). Further improvements in alloy design are under way in which existing nickel alloys and DS eutectics are being blended to give a fibre-reinforced structure with precipitates in the matrix. 

Some interesting differences are noted between amorphous and crystalline polymers when glass fibre reinforcement is incorporated into the polymer. In Figure 9.2 (ref. 10) it will be seen that incorporation of glass fibre has a minimal effect on the heat deflection temperature of amorphous polymers (polystyrene,... 

Figure 9.2. Heal deflection temperatures under a load of 1.82 MPa for selected polymers. Note that incorporation of glass fibre has a much greater effect with crystalline polymers than with amorphous ones (after Whelan and Craft courtesy of British Plastics and Rubber)...

Polymers below the glass transition temperature are usually rather brittle unless modified by fibre reinforcement or by addition of rubbery additives. In some polymers where there is a small degree of crystallisation it appears that the crystallines act as knots and toughen up the mass of material, as in the case of the polycarbonates. Where, however, there are large spherulite structures this effect is more or less offset by high strains set up at the spherulite boundaries and as in the case of P4MP1 the product is rather brittle. 

As with other crystalline polymers, the incorporation of glass fibres narrows the gap between the heat deflection temperatures and the crystalline melting point. 

As with the aliphatic polyamides, the heat deflection temperature (under 1.82 MPa load) of about 96°C is similar to the figure for the Tg. As a result there is little demand for unfilled polymer, and commercial polymers are normally filled. The inclusion of 30-50% glass fibre brings the heat deflection temperature under load into the range 217-231°C, which is very close to the crystalline melting point. This is in accord with the common observation that with many crystalline polymers the deflection temperature (1.82 MPa load) of unfilled material is close to the Tg and that of glass-filled material is close to the T. ... 

Laminates produced by impregnation of glass and carbon fibre with polyimide resins followed by subsequent pressing have found important uses in the aircraft industry, particularly in connection with supersonic airliners. Such laminates can be used continuously at temperatures up to 250°C and intermittently to 400°C. 

Non-self-extinguishing glass-reinforced grades (10, 20, 30% glass fibre) with heat distortion temperatures in the range of 120-140°C. 

---