Patent ID: 7169886
Filing Date: 2007-01-30
Classification: B29B,B29C

Abstract:
1. A method for controlling the viscoelastic properties of a polymer comprising the steps of; i. feeding a precursor polymer at a first volumetric flow rate as a melt into a first station that is a first means for applying a strain rate, ii. subjecting the polymer melt in the first station while the melt is under a compressional or elongational flow volumetric constraint to a total shear rate that comprises contributions selected from the group consisting of rotational flow about an axis that is parallel to the direction of flow of the melt, vibration in the transverse or longitudinal direction relative to the flow direction of the melt, and any combination thereof, iii. removing the melt from the first station at a second volumetric flow rate, iv. transferring the melt at the second volumetric flow rate into an optional second station that is a means for applying a strain rate, v. subjecting the polymer melt in the optional second station while the melt is under a compressional or elongational flow volumetric constraint to a total shear rate that comprises contributions selected from the group consisting of rotational flow about an axis that is parallel to the direction of flow of the melt, vibration in the transverse or longitudinal direction relative to the flow direction of the melt, and any combination thereof, vi. and transferring the melt optionally into one or more further optional stations that are means for applying a strain rate at further volumetric flow rates, vii. subjecting the polymer melt in each of the further optional stations while the melt is under a compressional or elongational flow volumetric constraint to a total shear rate that comprises contributions selected from the group consisting of rotational flow about an axis that is parallel to the direction of flow of the melt, vibration in the transverse or longitudinal direction relative to the flow direction of the melt, and any combination thereof, viii. cooling and solidifying the polymer melt into a solid in either a forming operation to produce a desired product or by forming pellets from the melt, in which the flow profile history that the polymer melt is subjected to is controlled by the choice of first, optional second and optional further volumetric flow rates, the temperatures of processing in the first, optional second and optional subsequent stations, and the shear rates exerted by the pressure flow, rotational flow and vibration in each or any of the first, optional second and optional further stations, and in which there are intermediary zones in between the first station and the optional second station and in between the optional second station and the optional further stations and in between any two of the further optional stations, and in which the temperatures in the optional intermediary zones are optionally used for additional control of the flow profile history of the melt, where the viscoelastic properties, Newtonian viscosity, pseudoplasticity, or any combination of these properties of a melt that would be obtained by remelting the solidified melt are changed from the properties of the precursor polymer.