| 摘要 |
<p>The apparatus comprises a main extruder (1-4) and an auxiliary extruder (5-8) placed at the outer end of the feeding screw (4) of the main extruder. By means of the main extruder (1-4), a plastics raw- material substantially free from cross- linking agents is extruded at an elevated temperature and, by means of the auxiliary extruder (5-8), a rather small quantity of a concentrated mixture of the molten plastic raw-material and of a cross- linking agent is injected into the molten plastic raw-material mass at a lower temperature. Into the mass extruded by means of the main extruder (1-4), some quantity of an activator accelerating the cross- linking and/or of an inhibitor retarding the cross-linking may be added. The injection is effected either adjacent the downstream end of the screw (4), or between the end of the screw (4) and a mixing means (14-18). <IMAGE></p> |
