| 摘要 |
Strips or rods of foamed stereo-specific polyolefins are compressed to a thickness of at most half the original thickness and then stretched. The foamed polyolefin, e.g. polypropylene, has a density below 300 gms./litre, and may be prepared by passing a mixture of polymer and azodicarbonamide through an extruder and mixing with n-pentane before finally passing out of the extruder. |
