Compression molding with protective sleeves for preforms

Protective containers are provided for transporting moldable preform charges used in precision molding operations, in which the moldable material includes a conductive filler in a thermosetting resin matrix. The granular moldable material is loaded into the containers and compacted. Next, the loaded containers are transported to a molding station, where each preform of the moldable material is ejected from its container. The containers are sufficiently rigid to hold their shapes under high compaction pressures, thus to determine preform shapes with greater precision. By surrounding the preforms, the containers minimize evaporative loss of monomer, maintaining the preforms in a condition more suitable for molding, and reducing the impact of monomer loss on the surrounding environment. Each such container can take the form of a sleeve, or may have an end wall incorporating a flexure at one end.