US Patent 7202328 Amorphous polymer article

Method of producing an article comprising providing a raw material in the form of a plurality of polymer elements, the polymer elements comprising an amorphous polymer; heating the materials to a temperature above a first predetermined temperature; and compacting the material whilst above the first predetermined temperature. The first predetermined temperature is the Tg of the polymer elements, the pressure is between 100 and 200 psi; and the temperature and pressure of compaction are sufficient to soften the outer portion of the polymer elements and to cause the polymer elements to bonds to each other without melting or softening of the inner portion of polymer elements. A product is produced having a structure which comprises cores of amorphous polymer that have not been softened or melted in the method, surrounded by a mass of softened and re-hardened material which bonds the cores together.