| abstract |
A method for manufacturing disentangled and oriented products from thermoplastic raw material by extrusion and a product manufactured according to the method. Thermoplastic raw material is extruded through a die in at least two stages. In the first stage the material, which is over the crystallization temperature, is pushed under high pressure through a narrow channel. The great adhesion forces make it possible to achieve high internal shear rate of the material, whereby the molecule chains will disentangle and straighten in the flow. In a second stage the material will be cooled in a channel with wider cross section, whereby the shear rate is kept high enough to conserve the material structure obtained in the first stage, and a suitable cross-sectional form of the polymer flow is achieved. After extrusion the extrudate is quenched very rapidly, which will conserve a high degree of disentangling and stretched molecule chain orientation in a finished product or an extrudate ready for further stretching. |