Process for the continuous production of high modulus articles from high molecular weight plastics
US5399308A · kind A · utility
Inventors
Key dates
| Filing date | Jan 14, 1993 |
| Grant date | Mar 21, 1995 |
| Priority date | — |
| Expiry date | Jan 14, 2013 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2023/0683
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process for producing a high modulus article includes forcing a high molecular weight plastic material, such as polyethylene, through a passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thus producing an extrudate. The plastic material is extruded while it is close to or at its melt temperature, and it is lubricated to obtain substantially plug flow through the passage. The speed at which the plastic material flows through the passage is adjusted so that the elongational velocity gradient at any longitudinal position within the passage does not exceed about 2.6 sec..sup.-1, thus minimizing the degree of molecular orientation in the extrudate. The extrudate can be deformed by drawing while it is maintained at or close to its melt temperature, thus producing an oriented, deformed extrudate. The oriented extrudate is then quickly cooled to preserve the orientation. A suitable plastic material is high molecular weight polyethylene with an average molecular weight lying between about 500,000 and about 1,500,000.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.