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Rheological and Dielectric Behavior of a Styrene−Isoprene−Styrene Triblock Copolymer in Selective Solvents. 2. Contribution of Loop-Type Middle Blocks to Elasticity and Plasticity
- Source :
- Macromolecules. 30:5877-5892
- Publication Year :
- 1997
- Publisher :
- American Chemical Society (ACS), 1997.
-
Abstract
- Rheological and dielectric behavior was examined for concentrated solutions of a styrene−isoprene−styrene (SIS) triblock copolymer in monomeric and polymeric I-selective solvents, n-tetradecane (C14) and a low-M homopolyisoprene (I-1; M = 1.4K). The I blocks had symmetrically once-inverted dipoles along the block contour, and their midpoint motion was dielectrically detected. The SIS solutions exhibited rubbery, plastic, and viscous behavior at low, intermediate, and high temperatures (T). Dielectric and viscoelastic data strongly suggested that the S and I blocks were more or less homogeneously mixed in the viscous regime. In the rubbery and plastic regimes, the S blocks were segregated to form spherical domains, and the I blocks took either the loop or bridge conformation. In these regimes, the inverted dipoles of the I blocks enabled us to dielectrically estimate the loop fraction, φ1 ≅ 60% in C14 and I-1. These loops, having osmotically constrained conformations, strongly affected the rheological prop...
- Subjects :
- Materials science
Polymers and Plastics
Organic Chemistry
Dielectric
Plasticity
Viscoelasticity
Styrene
Condensed Matter::Soft Condensed Matter
Inorganic Chemistry
chemistry.chemical_compound
Monomer
chemistry
Rheology
Polymer chemistry
Materials Chemistry
Copolymer
Elasticity (economics)
Composite material
Subjects
Details
- ISSN :
- 15205835 and 00249297
- Volume :
- 30
- Database :
- OpenAIRE
- Journal :
- Macromolecules
- Accession number :
- edsair.doi...........38fc65504465c916467713bdbcf29694