Actually no because to maintain a vacuum you would have to pump on it, i.e. pump out all the nasties through your vacuum pump.
The way in which many thermo plastic materials are recycled into the solid brownish/greyish/mottled lengths that are used to build deck material or park benchs is by heat and pressure. The plastics are shredded or ground and then mixed in a screw extruder which heats and mixes them together. The pressure has two functions; it causes the plastics to fuse together at a temperature well below their melting point or depolymerization temperature and it raises the temperature at which they start to depolymerize and outgas. |