Such materials are for instance semicrystalline thermoplastic polymers (polyamides, saturated polyesters, polyolefins, polyacetals); amorphous thermoplastic polymers such as polycarbonates, polyphenylene-oxide-based mixtures, acrylonitrile-butadiene-styrene, or thermoplastic elastomers such as polyurethane, etherpolyester, or polyolefins; heat-hardenable or reactive polymers such as unsaturated po