Elongational rheology of polymer melts and solutions

• Published in: Journal of applied polymer science Vol. 69; no. 12; pp. 2357 - 2367
• Main Authors: Collier, John R., Romanoschi, Ovidiu, Petrovan, Simioan
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 19.09.1998; Wiley
• Subjects: Applied sciences; constant strain rate; elongational flow; elongational viscosity; Exact sciences and technology; lyocell solution; microfibers; Organic polymers; Physicochemistry of polymers; polypropylene; Properties and characterization; Rheology and viscoelasticity; Viscosity; Chemical solution; Polyethylene; Molten state; Shear flow; Propylene polymer; Cellulose; Lignocellulosics; Experimental study; Elongational flow; Rheological properties
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/(SICI)1097-4628(19980919)69:12<2357::AID-APP7>3.0.CO;2-7

Elongational rheological properties of polymer melts and solutions may be measured using nonlubricated flow characteristics through a semihyperbolic converging die. The effects of body forces related to developing orientation in the fluid during converging extensional flow are so strong that the shearing contribution become negligible in comparison, eliminating the need for lubrication to achieve an essentially pure elongational flow. The effective elongational viscosities of polypropylene melts and lyocell solutions correlated with shear‐flow determinations were used to estimate the enthalpy and entropy changes as function of processing conditions. The flow of lyocell solutions through a converging die had, as a result, not only phase separation and cellulose crystallization, but also microfibers formation and high orientation. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2357–2367, 1998