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Investigation of the relationships between die build up and die swell
- Source :
- Polymer Engineering & Science. 49:333-343
- Publication Year :
- 2008
- Publisher :
- Wiley, 2008.
-
Abstract
- Die build up (DBU) is a common problem encountered during extrusion of polymers where material accumulates around the die exit and may cause defects in the surface of the product. This study was initiated to better understand the fundamental relationships between DBU and die swell. The study was conducted on a strand die extrusion system using an ethylene-octene polyolefin elastomer resin. This study demonstrated that die swell is not a root cause of DBU. It was shown that at constant shear rate, increasing the die L/D ratio results in an increase in DBU, while die swell decreases. The important variables influencing DBU for the resin used in this study were: the shear rate or shear stress in capillary portion of the die, the nominal residence time that the resin is exposed to the high shear stress in the die capillary, and the concentration of oligomers present in the resin or generated during processing. These data support the conclusion that DBU is due to the shear-induced migration of oligomeric species in the polymer to the die surface. Higher shear rates and stresses in the die promote this migration and result in a higher concentration of oligomeric species near the die wall. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
- Subjects :
- Materials science
business.product_category
Polymers and Plastics
General Chemistry
Die swell
Elastomer
Polyolefin
Shear rate
Shear (sheet metal)
chemistry.chemical_compound
chemistry
Materials Chemistry
Shear stress
General Earth and Planetary Sciences
Die (manufacturing)
Extrusion
Composite material
business
Subjects
Details
- ISSN :
- 00323888
- Volume :
- 49
- Database :
- OpenAIRE
- Journal :
- Polymer Engineering & Science
- Accession number :
- edsair.doi...........00fb6b350ce0ff044458f694a04d9d36