On chain entanglement in high-Tgamorphous polymers

It is well known that chain entangiement affect the rheological behavior of polymer melts and concentrated polymer solutions. A great deal of experimental and theortical work concerns this technologically important phenomenon. In practice, the effects of chain entanglement are always observed whenever a melt or a concentrated solution is subjected to external force. This occurs in almost all types of polymer processing. Extrusion, transport of melts, fiber and film formation, injection molding of thermoplastics, etc, are examples of processes where chain entanglement has an important effect on processing conditions, quality of products, selection of molecular weights, processing temperature, and rates of production.