An in-process ultrasonic approach to investigating the relaxation of orientation and disorientation of polymer melts

• Published in: Polymer engineering and science Vol. 48; no. 5; pp. 987 - 994
• Main Authors: Li, Jiang, Sun, Zhigang, Tatibouët, Jacques, Jen, Cheng-Kuei
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.05.2008; Wiley; Society of Plastics Engineers, Inc; Blackwell Publishing Ltd
• Subjects: Applied sciences; Design and construction; Exact sciences and technology; Mechanical properties; Methods; Organic polymers; Physicochemistry of polymers; Polyethylene; Polymer melts; Properties; Properties and characterization; Sensors; Structure, morphology and analysis; Ultrasonic technology; Ultrasonic testing; United States; Molten state; Disorientation; Shear flow; Propylene polymer; Temperature effect; Capillary flow; Experimental study; Melt index; Molecular relaxation; Pressure effect; Low density ethylene polymer; Molecular orientation; Olefin polymer; Measurement method; Ultrasonic method; Rheological properties
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.21023

The orientation and relaxation behaviors of a low‐density polyethylene melt and polypropylene melts with different melt indices undergoing a shear flow in a restricted channel were investigated by using ultrasound. A capillary rheometer was used to force the polymer melt through a slit die equipped with pressure, temperature, and ultrasound sensors, and the variation of ultrasound velocity traversing the melt was measured. Experimental results revealed that due to different mechanisms involved, the relaxations of orientation and disorientation processes show different dependences of ultrasound velocity on shear rate, temperature, and melt index. POLYM. ENG. SCI., 2008. Published 2008 Society of Plastics Engineers