TECHNOLOGY FOCUS - POLYMERS - Preferred Resin Systems: Epoxy resins based on Bisphenol A (or F) di glycidyl ether and methylhexahydrophthalic anhydride, with or without a latent catalyst, showing a viscosity of less than 200 (preferably 150 or below) mPa.s at 50 degrees C over a period of more than 2 days, preferably more than 2 weeks; or resins based on diphenylmethane di-isocyanate (MDI), preferably on MDI and bis-4,4'-glycidoxyphenyl-propane, and a latent catalyst, showing a stability of more than 2 days, preferably more than 2 weeks, in the impregnated graphite at room temperature (RT).Preferred Products: Impregnated EXG containing up to 50 (preferably 5-25, especially 10-20) wt% isocyanate, isocyanurate, urethane, polyurethane and/or epoxy resin. The EXG precursor may also contain optionally electrically conductive ceramic or mineral fillers. The EXG products comprise two co-adherent networks, one a coherent structure of electrically and thermally conductive EXG and the other a coherent system of plastic penetrating into the graphite, preferably with the above (hardened) resin systems only in zones near the surface or in part of the product and with no closed resin film on the surface (so that electrical contacts can be formed).Preferred Method: The impregnated graphite is formed and thermally cured at the same time. The open-pore precursor shows an ash value of not more than 4 (preferably not more than 2) wt% and a bulk density of 0.1-8 (preferably 0.5-1.3) g/cm3, and the resin systems used show a viscosity of less than 100 (preferably less than 70) mPa.s at 50 degrees C for epoxy resins, or less than 100 (preferably less than 50) mPa.s at RT for isocyanate-based systems. Resin systems with a latent catalyst are hardened in the EXG at 120-180 degrees C for less than 2 hours to less than 15 minutes depending on temperature; systems without a catalyst are hardened at 120-180 degrees C for less than 40 hours to less than 24 hours depending on temperature. The EXG precursor absorbs up to 100 (preferably 10-25) wt% of its own weight of the resin system during impregnation. The EXG may be mixed with fillers as above, processed to a filler-containing precursor and then impregnated with resin. EXAMPLE - Sheets of partly recompacted expanded graphite with an ash content of less than 2 wt% , a thickness of 1 mm and a bulk density of 1 g/cm3 were vacuum-impregnated for 5 hours at 10 mbar with Rutapox M4-1158-CK (RTM: epoxy resin system; viscosity 40 mPa.s at 50 degrees C; plus latent catalyst), both the graphite and the resin being preheated to 50 degrees C. After wiping off excess resin, the impregnated sheets were hardened for 30 minutes at 150 degrees C in a fan oven to give a product with a resin content of 14.6%, showing no cracks or blisters. This product showed an electrical resistance of 0.39 (0.52) m-ohm and a helium permeability (at 2 bar) of 0.04 (0.07) mg/m2/s. Values in brackets are for the same graphite impregnated with 15% epoxy resin with a viscosity of 70 mPa.s at 50 degrees C (Rutapox VE 4834); corresponding values for un-impregnated graphite were 0.28 m-ohm and 0.32 mg/m2/s.