2318 高分子流体の不安定流動と粘着・凝集に関する研究(S42-4 複雑流体の流動現象(4),S42 複雑流体の流動現象)  [in Japanese] 2318 Influence of adhesion and cohesion failure on flow instability of polymeric fluid  [in Japanese]

In the extrusion processing of the polymer melt, the extrudate often suffers melt fracture, which is classified into "sharkskin", "spiral fracture", or "wavy fracture" depending on the surface roughness. The mechanism of "sharkskin" was proposed here based on the microscopic observation at the slit exit. The polymer was linear Polydimethylsiloxane (PDMS). The visualized results showed that "sharkskin" occurs because of the adhesion/cohesion failure at the die inside, or the adhesion of the polymer to the die exit edge side. In addition, in order to suppress "sharkskin", the flow of the slit exit was controlled using air jet and a protruded edge, and their influence on the exit flow was investigated.