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Abstract

A method for controlling the viscoelastic properties of a polymer comprising the steps of feeding a polymer melt into a first and optional subsequent means for applying a strain rate, each means for applying a strain rate being underfed or overfed according to the relative volumetric flow rates into the out of each means for applying a strain rate. The method further comprises subjecting the polymer melt in the means for applying a strain rate to a total shear rate that comprises contributions selected from the group consisting of pressure flow through an orifice, 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. The flow profile history that the polymer melt is subjected to is controlled by the choice of first, optional second and optional subsequent volumetric flow rates, the temperatures of processing in the first, optional second and optional subsequent means for applying a strain rate, 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 means for applying a strain rate. There are optionally intermediary zones in between the first means for applying a strain rate and the optional second means for applying a strain rate or the optional second means for applying a strain rate and the optional subsequent means for applying a strain rate or both, and the temperature in the optional intermediary zones are optionally used for control of the flow profile history of the melt.

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