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Modifying the rheological properties of polypropylene under elongational flow by adding polyethylene
- Source :
- Journal of Rheology. 63:11-18
- Publication Year :
- 2019
- Publisher :
- Society of Rheology, 2019.
-
Abstract
- Adding polyethylene greatly affects the rheological response of isotactic polypropylene (PP) under uniaxial elongational flow. Though strain hardening in the transient elongational viscosity barely appeared in pure PP, we induced strain hardening by adding low-density polyethylene (LDPE) to PP, even though the blends showed a phase-separated structure. During elongational flow, LDPE droplets dispersed in the PP were deformed in the flow direction. Because LDPE shows marked strain hardening in the elongational viscosity, the deformed LDPE droplets behaved as rigid fibers as the strain increased. Consequently, the PP between the fibrous LDPE droplets experienced excess localized deformation, which increased the apparent elongational viscosity. Furthermore, adding the high-density polyethylene (HDPE) increased the drawdown force—defined as the force required for uniaxial stretching of a molten polymer in the nonisothermal condition. This behavior comes from the rapid crystallization of HDPE, which causes the deformed HDPE particles to act as rigid fibers in the molten PP and enhances the PP crystallization, which increases the elongational stress.
- Subjects :
- Polypropylene
Materials science
010304 chemical physics
Mechanical Engineering
technology, industry, and agriculture
Strain hardening exponent
Polyethylene
Condensed Matter Physics
01 natural sciences
chemistry.chemical_compound
Viscosity
Low-density polyethylene
chemistry
Rheology
Mechanics of Materials
0103 physical sciences
General Materials Science
High-density polyethylene
Deformation (engineering)
Composite material
010306 general physics
Subjects
Details
- ISSN :
- 15208516 and 01486055
- Volume :
- 63
- Database :
- OpenAIRE
- Journal :
- Journal of Rheology
- Accession number :
- edsair.doi...........0dde0e5ee3877d29a8e6a8d0963a910d