In-line characterization of polymer deformation in melt and solid phase processing

Abstract

Constitutive relationships obtained from in-process measurements on polymers that have been subjected to typical solid or melt phase processing strain-temperature-time histories can be used for enhanced modelling of deformation and flow (e.g. finite element analysis/computer aided design), or to provide new information on shear and extensional flows. In some circumstances in-line measurement may be the only practical route to reliable constitutive data. In the case of melts, such measurements may also be used for real time assessment of polymer state and for process control. The in-process measurements discussed in this paper are specifically concerned with ‘in-line’ rheometry, where pressure, temperature, stress, strain and strain rate measurements are made upon polymers in actual process geometries, under actual process conditions. Examples of accurate in-line measurements of polymer rheometry in an injection moulding nozzle and in a model solid phase forming process—uniaxial drawing of polymers—are discussed.