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New polyimide foams and polyimide foam filled honeycombs are currently being developed at NASA, its licensee Sordal Inc. (USA) and Newmet (UK) under the trade name Solrex J . These materials are foreseen for Space, Aerospace, Maritime & Medicine applications. In this paper selected properties of these new materials with different densities are described.The investigated key properties are compression strength, thermal conductivity and moisture gain. The dependence of these prop-erties on density, temperature and thermal cycling is discussed. Limits of the used characterisation methods are discussed. Possible applications are defined.

Carbon fibre reinforced copper ma& composites possess interesting properties of copper, i.e., excellent thermal and electrical conductivities, but the properties of carbon fibre, i.e., a small thermal expansion coefficient dominate the mechanical behaviour. Since the desirable properties of the composite can be obtained by selecting the amount and type of the carbon fibres, it is considered to be suitable for use as electric and electronic materials like special heat sinks. It is a competitive material which is able to overcome some of the disadvantages of e.g. CopperMolybdenum, Copper-Invar or Aluminium-Silicon Carbide.Copper matrix composites with high conducting endless carbon have been investigated in different research groups for several years, but copper matrix composites with high conducting short fibres are a new and promising field of research. Short carbon fibre reinforced copper composites have been made by hot-pressing of copper coated carbon fibres chopped into different lengths (60 pm -2 mm). Due to a special production route -electroless copper coating -a good distribution of the fibres in the matrix and a good interfacial contact is obtained. The fibre length distribution influences strongly the properties of the composite. During hot pressing, the carbon fibres take on a preferred orientation in a plane perpendicular to the hot pressing direction. Within this plane the fibre orientation is random. Samples using PITCH-and PAN-type fibres have been produced. The volume content of carbon fibres has been varied in a range of 38 -64 vol.%.The microstructure of the composites has been investigated using SEM and optical microscope. Measured properties, i.e., thermal conductivity and coefficient of thermal expansion have been compared with microstructural results and results obtained from mathematical models. Up to now these composites provide a thermal conductivity of about 250-300 W/mK in two dimensions and about 140 W/mK in the third dimension. The coefficient of thermal expansion (CTE) can be tailored in a range of 4-10 ppm/K by changing the content of carbon fibres. The relatively low density of about 4-6 g/cm3 is also of importance wherever weight reduction is desired. The results are compared with composites produced by powder metallurgical route and composites made with low conducting short carbon fibres respectively.

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