Molded or Machined Articles
The polyamide-imides used for molded articles are also based on aromatic diamines and trimellitic acid chloride, but the diamines are different from those used in the products used for coatings and the polymer is more fully imidized prior to compounding and pellitizing. Resins for injection molding include unreinforced, glass-fiber reinforced, carbon fiber reinforced, and wear resistant grades. These resins are sold at a relatively low molecular weight so they can be melt processed by extrusion or injection-molding. The molded articles are then thermally treated for several days at temperatures up to 260°C (500°F). During this treatment, commonly referred to a postcure, the molecular weight increases through change extension and the polymer get much stronger and more chemically resistant. Prior to postcure, parts can be reground and reprocessed. After postcure, reprocessing is not practical.
Read more about this topic: Polyamide-imide, Fabrication
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