In the case of recycled material, vacuum pumps remove air inclusions, moisture and adhesives from the molten plastic. They extract all the low molecular substances in order to obtain the optimum quality, i.e. a smooth surface, high strength, better insulation properties and a lower out gassing rate, resulting in recyclable material which achieves the same level as new material.
Production units for rubber parts used in the automobile industry require vacuum to evacuate the die casting moulds, to avoid air bubbles and to accelerate the rubber mass.
Solid State Polymerization
Solid State Polymerization (SSP) is a process in which the polymer chain lengths are increased by heat in the absence of oxygen and water, by means of either vacuum or purging with an inert gas to drive off the by-products of reactions. The reaction is driven by temperature, pressure, and the diffusion of by-products from the interior of the pellet to the surface. SSP is an important step frequently used after melt-polymerization for the purpose of enhancing the mechanical and rheological properties of polymers before injection blow molding or extruding. The SSP technique is widely applied in the industrial manufacturing of bottle grade PET, films and superior industrial fibres.