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Correlation between rheological behaviour in uniaxial elongation and film blowing properties of various polyethylenes |
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| Authors: | Helmut Münstedt Thomas Steffl Anneli Malmberg | ||
| Institution: | (1) Institute of Polymer Materials, University Erlangen-Nürnberg, Martensstr. 7, 91058 Erlangen, Germany;(2) Present address: Teadit International, Rosenheimer Str. 10, Kufstein, 6330, Austria;(3) Borealis Polymers AB, PO R& D, 44486 Stenungsund, Sweden | ||
| Abstract: | Six various low density polyethylenes and one blend were rheologically characterized in elongation. Their different strain-hardening behaviour could qualitatively be related to their molecular structure. All the materials were blown to films on laboratory equipment under various conditions. The take-up force and the film homogeneity were determined quantitatively, the bubble stability was visually assessed. The bubble stability increased with growing take-up force. The take-up force was found to be the stronger the higher the elongational viscosity was. The homogeneity of film thickness is not related to the bubble stability but to the occurrence of strain hardening in the uniaxial elongational experiment at high Hencky strains. Measurements of the uniaxial elongational behaviour of polyethylene melts are a valuable and promising way to assist the development and optimisation of film blowing materials.
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| Keywords: | Polyethylene Elongational rheology Strain hardening Film blowing Bubble stability Take-up force Homogeneity of film thickness | ||
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