| 摘要 |
<p>A twin-screw extruder (1) equipped with a vacuum degassing arrangement, e.g. below 5 mbar (10, 11, 12, 13), is fed (7) with polymer containing a nucleating agent. A high pressure, e.g. 70 to 300 bar, is then generated by a subsequent gear pump (16) which supplies a static mixer (17) where a blowing gas, e.g. nitrogen or carbon dioxide, is injected (21) in a supercritical state. This is followed by a second gear pump (22) to feed the extrusion nozzle (23).</p> |
