Study on the solid-state shear pulverization process in single screw extruder illustrated by polyethylene as an example

摘要

Investigations were carried out in a conventional single-screw extruder equipped with modified heating system of a cylinder,which of the first zone was heated and the other one cooled.Four thermoplastic polymers were the subjects of investigations:PE-HD,PE-LD,PS and PP.From among them only PE-LD undergoes the effective pulverization in the extruder used.The effects of speed of screw rotation as well as temperature of heating of a cylinder conversion zone on size reduction degree of PE-LD pulverized (Fig.2,Table 1) were determined.It has been stated the fine PE-LD powder formed in the wide ranges of these parameters and energy demand appeared to be relatively small.Second zone of a cylinder (feeding zone) should be intensively cooled because only in such case the polymeric powder was most fine.The use of a special screw tip (Fig.4) let take it off quickly from the cylinder immediately after the process interruption and,as a consequence,let characterize the solid bed.PE-LD pulverization goes rapidly at narrow temperature range below the temperature of polymer melting.