Polymer melts resist flow. In viscous flow the energy producing the flow is dissipated as heat. During flow some energy may be stored, giving rise to elastic effects, and, should the stress exceed some critical value, fracture may occur. When we are considering simple fluids then the viscosity may be clearly defined. The earlier chapters have shown that the viscosity of a polymer melt depends strongly on temperature, pressure and rate of deformation. This chapter introduces one further variable: geometry.
KeywordsDraw Ratio Dead Zone Melt Flow Index Deborah Number Extrusion Pressure
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