Abstract:

   The flow instability of polymer melts is a very complicated problem, which is still in intense debate. Systemic and quantitative research on this problem with new idea and viewpoints has much theoretical and practical meaning. In theory, it will help us clarify the blurry understanding on this problem, and open out the non-linear viscoelastisity of polymer melts. In practical, we can control and use the melts flow rules at high speed for production by broadening and optimizing production technology. For three years, a series of systemic research have been carried out, a clear thoughts of study has been cleared up, many significant results have been acquired and the preconcerted plan has been accomplished. The main physical parameters and experiment techniques, which describe flow instability of polymer melt quantitatively have been ascertained. The flow instability of a large kind of polyolefin melts has been described quantitatively, and the differences among the melts have been distinguished, especially, the marked difference. The molecular mechanism and interfacial mechanism of melts flow instability was researched by considering molecular structure, condensed phase structure, linear and non-linear viscoelasticity of polymers. Moreover, how the material structure, components, temperature, interface status, copolymerization, blending, filling, lubricating etc. influence on flow instability of melts was studied. At last, some measure of improving and utilizing flow instability of polymer melt were explored.

Key words: Polyolefine; Melts; Extrusion pressure vibration; Sharkskin fracture; Slip at wall