2. Injection-foaming processes

Injection-foaming processes for producing microcellular polymeric materials have been extensively analyzed over the last thirty years . The microcellular structure is formed by the nucleation, growth and sometimes coalescence of bubbles in the polymer matrix. Gas is introduced into the polymer matrix either chemically or physically. In the physical route, inert gases, carbon dioxide (CO ₂ ) or nitrogen (N ₂ ), are introduced directly into the polymer. In the chemical route, the gas is obtained from the...