Duroplast is a composite thermosetting plastic, a close relative of formica and bakelite. It is a resin plastic reinforced with fibers (either cotton or wool) making it a fiber-reinforced plastic similar to fiberglass.
Duroplast was used by the Communist German Democratic Republic state owned automobile manufacturer called VEB Sachsenring Automobilwerke Zwickau from 1957 to 1990 until the fall of Communism, but production ended after German Reunification in 1991. It was the material used to produce the body of the Trabant people's car. There were four main versions of the Trabant, the 1963-1990 Trabant 601 was the longest running. The successor company is called HQM Sachsenring GmbH.
Duroplast is light and strong. It is made of recycled material, cotton waste and phenol resins. Because it can be made in a press similar to shaping steel, it is more suitable for volume car production than fibreglass.
Duroplast cannot be further recycled, and burning it produces toxic fumes, so disposing of the bodies of old Trabants has required novel solutions. Despite this, its components are non-toxic to animals, and there are stories of pigs, sheep or other farm animals consuming Duroplast as depicted in the movie Black Cat White Cat and described in a song by the Serbian band Atheist Rap.
The same Zwickau plant that started making the Trabant developed a solution for Duroplast disposal in the 1990s. After removing the glass, engine, and steel frame, the Duroplast is shredded and used as an aggregate in cement blocks for pavement construction. This was featured in an episode of the program Scientific American Frontiers on the American PBS TV channel.
A Berlin biotechnology company has also developed a solution to the duroplast problem: a bacterium that will completely compost a Trabant's Duroplast body in 20 days.