Deformation flow profile, extrusion

Figure 2. Schematic drawing of the effects of EDR (top), extrusion temperature (middle), and die angle (bottom) on the deformation flow profiles for two typical HDPE s having a low and a high MW.

All the results of DSC, elastic recovery, and x-ray measurements on the sample portions formed under characteristic deformation flow components indicate that the complex stress strain field in an extrusion die produces markedly different deformation flow profiles on crystalline-state extrusion of HDPE, but results in no significant effect on the morphology and properties of the extrudates prepared under the conditions used in this work. It is remembered, however, that an earlier electron microscopy study found marked morphological variations across the radius of HDPE extrudates prepared at higher temperatures (134 to 137°C) under the combined effects of chain orientation and pressure (4). The T, of the undeformed isotropic... 

In the present extrusion of HDPE ribbons, the deformation patterns were examined by the deformation of parallel ink marks preimprinted on the surface of a HDPE (Figure 1-d). At EDR >12, the low and high MW HDPE exhibited a typical shear parabola and a W-shape deformation profile, respectively, with both characteristics enhanced at higher EDR as shown in Figure 2. These characteristics of the deformation patterns are in well agreement with our previous observations (3) and further confirm the previous conclusion that there is no significant effect of cutting a billet into two halves and/or coextrusion of a film with the split billet halves on the deformation flow patterns. 

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