Abstract: Multilayer structure based on thermoplastic polymers which is substantially devoid of vinyl chloride polymers and of plasticizers of low molecular mass and which comprises at least 3 layers: a first layer (A) comprising at least 60% by weight of at least one polyolefin of controllable crystallinity defined as comprising at least 90% of ethylene, of propylene or of butene and as having a softening temperature of less than 121° C., the thickness of the first layer being at least 20% of the total thickness of the structure and the first layer having a modulus of elasticity of less than 350 MPa; a second layer (B), positioned between the first layer (A) and the third layer (C), comprising at least 40% by weight of at least one polyolefin of controllable crystallinity, the second layer having an overall softening temperature of less than 121° C.

Abstract: A process for processing a thermoplastic, which includes, in succession, the following steps: (1) a molten semicrystalline thermoplastic extrudate is cooled to a temperature T1 which is greater than the crystallization temperature (Tc) of the thermoplastic and is less than Tf+5° C., Tf 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 T3 which is between Tc and Tf, for a duration at least equal to the average relaxation time (&tgr;3) of the thermoplastic at the relaxation temperature, and after the drawing; (4) next, the extrudate is quenched to a temperature T4 which is less than Tc.

Abstract: A process for preparing thermoplastics comprising the steps of cooling an extrudate to a temperature T1, drawing the molten extrudate, relaxing the extrudate at a temperature T3 for a duration of at least the average relaxation time of the thermoplastic at the relaxation temperature, and quenching the extrudate to a temperature T4. The process enables the manufacture of films consisting of at least one propylene homopolymer with a thickness of 100 to 250 &mgr;m and having a hot shrinkage of at most 20%, a haze of less than or equal to 3% and a total transparency with respect to air of greater than 70%.

Abstract: Tube comprising:(a) an inner layer essentially consisting of a copolyester obtained from at least one poly(alkylene oxide) glycol, 1,4-cyclohexanedicarboxylic acid and 1,4-cyclohexanedimethanol;(b) an interlayer essentially consisting of an ethylene-vinyl acetate copolymer and/or of a copolymer containing at least one polyamide block and at least one poly(alkylene oxide) block; and(c) an outer layer essentially consisting of a copolyester obtained from at least one poly(alkylene oxide) glycol, 1,4-cyclohexanedicarboxylic acid and 1,4-cyclohexanedimethanol.This tube may advantageously be used in medical applications.

Abstract: Multilayer tube or sheet including an intermediate layer, an inner layer bonded to the inner surface of the intermediate layer and an outer layer bonded to the outer surface of the intermediate layer, in which the intermediate layer comprises a polymeric material chosen from terpolymers of ethylene, of maleic anhydride and of an acrylate.