2. Foam injection molding processes

Injection-foaming processes for producing microcellular polymeric materials have been extensively studied over the past thirty years . The microcellular structure is formed by the nucleation, growth, and sometimes coalescence of bubbles within the polymer matrix. Gas is introduced into the polymer matrix through either a chemical or physical process. In the physical method, inert gases, such as carbon dioxide (CO ₂ ) or nitrogen (N ₂ ), are introduced directly into the polymer. In the chemical method,...