The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 23, 1999
Filed:
Dec. 19, 1996
Jean-Pierre Ibar, New Canaan, CT (US);
Other;
Abstract
A method for controlling the viscosity of molten polymers, such as polycarbonate, takes place prior to a molding operation such as injection molding, extrusion, thermoforming or blow molding. When a significant reduction of viscosity is desirable, the plastic melt is submitted, at constant temperature, to the action of a vigorous mechanical extensional shear vibration, with minimum or no external pressure, at a constant amplitude and frequency, causing the melt to become highly elastic, and simultaneously it is fatigued, for a certain time at that temperature, maintaining this high elastic state, until the macromolecules have partially or totally disentangled, in a controllable manner, at which stage the melt is ready for a molding operation such as a simple quenching operation or an extrusion process followed by quenching to produce pellets or compounds with a better mix or a lower viscosity when remelted, or an injection molding operation where the melt viscosity has been greatly reduced allowing a better processability of the injected part, for instance allowing the use of a lower temperature of injection, a lower pressure of injection or both.