Shrinkage of PBT, PP and PE in Central Tube Buffering Process

摘要

In this study the we were comparing the post shrinkage behavior of PBT, PP and HDPE. For that purpose we developed a central tube buffering process with minimized post shrinkage and possibility to control the fiber excess length from negative to very high positive values. The condition for low post shrinkage is that the material is crystallizing in cooling trough as much as possible. This was realized by so called 'relaxation zone', where the tube was heated up by a hot water. At the same time the tube must be under no tension to enable the relaxation. A series of ribbon buffering processes with excess lengths from zero to very high values were used to compare the three materials. The line configuration and test results are presented and analyzed in this paper.