Insulation materials, thermal mechanical strength

A large fraction of practical catalysts consists of transition-metal or metal oxide nanoparticles dispersed onto the surface of insulator or semiconductor oxides that function as support materials. For industrial applications, the supports employed are selected on the basis of their surface area (high surface area is usually, but not always, desirable), high thermal and hydrothermal stability, chemical stability, and mechanical strength. 

Addition of a filler such as AKO s an alternate method to reduce creep. As shown in Table 3 this filler also increases mechanical strength as well as lowering the coefficient of thermal expansion. The latter aspect can be an important consideration when trying to match material coefficients of expansion in an encapsulating situation. It should also be noted that volume resistivity measurements of unfilled material (see Table 3) indicate these formulations provide satisfactory electrical insulation for encapsulating purposes. 

PI is widely used as a protective material or an insulation material in the electronic field due to its good properties, e.g., high mechanical strength, high thermal resistance, and solvent resistance. Selected physical properties of a thermoplastic PEI are shown in Table 15.5. Ultem is obtained from bisphenol A dianhydride and MPD. It has a glass transition temperature of 217°C. It should be emphasized that there are a lot of different PI resins with deviating properties. Thus the data given in Table 15.5 are not plainly representative for Pis. 

Solid foams have important applications as useful materials. The presence of gas bubbles results in a substantial reduction in the average density of the material. It also reduces the thermal conductivity, making sohd foams very suitable for insulation materials. Solid foams find applications as lightweight material in mechanical components. In this case, the challenge is to achieve an effective compromise between weight and strength. In foods, such as bread, icecream, or marshmallows, solid foams help to give a pleasant texture. 

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