AbstractSolvent‐cast metal‐filled composites made of polymethyl methacrylate and aluminum or copper exhibited electrical resistance behavior as is predicted by the percolation and tunneling mechanisms. A precipitous change in volume resistivity of about 1010ohm‐cm was found to be thermally dependent at volume concentration of filler in the range from 17 to 19.5 percent. Materials with compositions at the conductive‐non‐conductive threshold showed semi‐conductor behavior and exhibited memor