Melt-extrusion of polymer which is capable of forming an anisotropic melt phase to form large shaped articles exhibiting improved polymeric orientation
US4734240A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 24, 1986 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Jan 24, 2006 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2105/0079
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An improved technique is provided to melt-extrude a liquid crystalline polymer to form large elongated solid shaped articles which exhibit significantly improved polymeric orientation. The molten polymer which is capable of forming an anisotropic melt phase is extruded through a converging die that is provided with at least one enclosed cooling zone at an interior location within the flowing molten polymer wherein a cooling fluid is circulated. This cools the molten polymer adjacent the cooling zone with the concomitant increase in its melt viscosity. Such increased melt viscosity at the interior of the stream of the molten polymer contributes to the uniformity of the polymeric orientation imparted within the converging die as well as during subsequent drawdown outside the extrusion orifice. Such improved polymeric orientation leads to the formation of an improved product (e.g., a three-dimensional rod) which exhibits an unusually high tensile modulus in the direction of its length. The present invention accordingly overcomes difficulties encountered in the prior art wherein melt-extruded shaped articles significantly larger than fibers heretofore often have exhibited substantial i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.