Different types of molds
Moules pour l'injection des thermoplastiques

Polymer injection molding relies on temperature-dependent changes in polymer properties: in the press barrel, molten polymers are viscoelastic, compressible fluids, and are transferred in this state to the mold cavities.

The mold is maintained at a temperature below the glass transition temperature T _g for amorphous polymers and below the crystallization temperature T _c for crystalline polymers. In the mold, the polymer temperature falls below T _g for amorphous polymers and below T _c for crystalline polymers: the polymer enters the solid state.

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