Patent ID: 6174479
Filing Date: 2001-01-16
Classification: B29C,B29K,Y10T

Abstract:
Process for processing a semicrystalline thermoplastic, which includes, in succession, the following steps:(1) a molten semicrystalline thermoplastic extrudate is cooled to a temperature T.sub.1 which is greater than the crystallization temperature (T.sub.c) of the thermoplastic and is less than T.sub.f +5.degree. C., T.sub.f denoting the melting point of the thermoplastic;(2) next, the extrudate is drawn in the molten state;(3) next, the extrudate is relaxed, at a temperature T.sub.3 which is between T.sub.c and T.sub.f, for a duration of at least equal to the average relaxation time (.tau..sub.3) of the thermoplastic at the relaxation temperature and after the drawing;(4) next, the extrudate is quenched to a temperature T.sub.4 which is less than T.sub.c.