pps proceeding - Abstract Preview
pps proceeding
Symposium: S07 - Fibers and Films
Oral Presentation
 
 

Production of Graded Structures in Films

Wibbeke Andrea (1)*, Schoeppner Volker (1)

(1) University of Paderborn - Paderborn - Germany

Components with graded structures have modified properties in spatial direction. To cope with the increasing demands on materials and components, the production of such components is currently field of research of the Collaborative Research Centre Transregio 30. On the one hand a gradation can be introduced by a local heat treatment after the polymer stretching process. The local heat treatment of a stretched amorphous polycarbonate film (Makrolon 2805) was investigated here with a hot air fan, a heater and a laser and afterwards the mechanical properties of the heat-treated area were analyzed. The highest gradation intersection could be generated with a heater. By measuring the mechanical properties it was shown that the orientations are almost completely annealed. Thus, a soft point is formed, which can find application as a deformable element. Another way to produce a graded structure in a polymer film is the local irradiation crosslinking. Here one radiation-crosslinkable polyethylene film (BorPEX ME 2592) was irradiated under local shielding. In a subsequent step the locally crosslinked film was formed uniaxially. It was evident here, that an exclusive deformation takes place in the not-crosslinked area during hot-forming, while the crosslinked area remained unchanged. The gradation produced here could be shown by measurement of residual stresses in the polarizing microscope. Furthermore also in the thermoforming of locally crosslinked films it could be shown, that the crosslinked area is formed less on not crosslinked area’s expense, without setting a locally different temperature. In this way, the deformation occurring can be set locally, thin spots can be prevent and a constant wall thickness distribution can be generated.