Polymer rheology-challenges for the 21~(ST) century

摘要

Rheological data are used in the plastics industry for polymer characterization, quality control, process control, and process modeling. In each of these fields, there remain significant barriers to progress. The challenges in polymer characterization are to develop experimental techniques for the rapidand precise measurement of linear viscoelastic properties and for evaluating the response of a melt to extensional deformations. A powerful aid in keeping a manufacturing process under statistical control is the use of an on-line rheometer as a process sensor for automatic control. A remaining challenge is the development of an in-line melt rheometer that would eliminate the need for gear pumps and reduce the time delay resulting from the transit of melt from the sampling point to the rheometer. While computational fluid dynamics has been applied with success to the simulation of serveral melt forming processes, major problems remain when melt elasticity plays an important role. In addition, present simulation techniques do not incorporate models for gross melt fracture, sharkskin and wall slip.