高分子溶融体のダイ内多層流動の粘弾性解析(<小特集>非ニュートン性,機能性を示す複雑流体の流動と応用)

概要

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In multi-layer co-extrusion of polymer melts, various kinds of interfacial instabilities occur due to processing conditions, die geometry, and the rheological properties of each layer. Suppressing the interfacial instabilities is a crucial task in manufacturing a multi-layer polymer film of high functionality. However, multi-layer flow of viscoelastic fluids has been poorly understood. We performed a course of viscoelastic simulations of multi-layer flow to clarify the flow and stress states, and investigated the effect of channel geometry and the layer arrangement of viscoelastic fluids with different rheological properties on it. It was found that by arranging the fluid with higher viscosity at the outer-most layer, large strain rate developed in the second layer of a fluid with lower viscosity. Furthermore, change of thickness of layers caused by die channel enhanced the jump of the normal stress difference at interfaces. This behavior was most enhanced in the arrangement of the high-viscosity fluids at the outer-most layer. It is supposed that this elasticity inhomogeneity might be an important factor controlling the interfacial instabilities in viscoelastic multi-layer co-extrusion.
一般社団法人日本機械学会の論文
2009-05-25