Measurement of elongation viscosity for polymer melts by fiber spinning

✍ Scribed by Gwo-Geng Lin; Ming-Chong Hu

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 181 KB
• Volume: 16
• Category: Article
• ISSN: 0730-6679
• DOI: 10.1002/(sici)1098-2329(199723)16:3<199::aid-adv4>3.0.co;2-o

✦ Synopsis

The elongation behavior of various polymer melts extruded from the single screw extruder has been studied. Low-density polyethylene, high-density polyethylene, polypropylene, and their short glass-fiber (GF)-filled composites were used. It was found that the spinning stability was good but the drawability was poor for GF-filled polymers. The elongation viscosity was measured by use of a Gottfert tensiometer (Rheotens) in the strain rate range from 0.1 to 4 s Ϫ1 . In regard to the viscosity calculations, a very convenient and straightforward method, especially for molten materials without die swell, is presented. All the sample melts showed slight tension thinning; that is, the elongation viscosity decreased along with the strain rate. It was also found that the elongation viscosity of the GF-filled polymer may increase along with the fiber content up to a critical value, and then drop if more fiber is added. The influence of the die geometry on the viscosity measurement is discussed.