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Volume 32 (2004)
- Issue 5 Pages 235-
- Issue 4 Pages 155-
- Issue 3 Pages 113-
- Issue 2 Pages 65-
- Issue 1 Pages 3-
Volume 32, Issue 4
Displaying 1-9 of 9 articles from this issue
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Original Articles
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Hiroshi Watanabe, Takuya MoriArticle type: Original Article
2004 Volume 32 Issue 4 Pages 155-160
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSFor a series of aqueous solutions of perfluorooctyl sulfonate (C8F17SO3−; abbreviated as FOS) micelles having a mixture of tetraethylammonium (N+(C2H5)4; TEA) and tetramethylammonium (N+(CH 3)4; TMA) ions as the counter cations, linear viscoelastic behavior was examined at 20°C. The solutions had the same FOS concentration (0.045 mol L−1) and various TEA fraction in the counter cations, φTEA = 0 − 1, and the spherical FOS micelles therein were connected into threads and further organized into dendritic networks. For φ TEA ≥ 0.5, the FOS threads/networks exhibited the Maxwell-type terminal relaxation reflecting their thermal scission. In this range of φTEA, the terminal relaxation time τ increased with decreasing φTEA while the steady state compliance Je was insensitive to φTEA. On a further decrease of φTEA below 0.3, τ became insensitive to φTEA and Je gradually increased possibly because the motion of the threads in the unscissored form became faster than the thermal scission to govern the terminal relaxation.These rheological features were discussed in relation to the effects of TEA and TMA on the thermal scission of the FOS threads/networks: Since the charge was the same for TMA and TEA but the bare radius was smaller for TMA, the TMA cations should be preferentially bound on the FOS thread. The thermal scission of the FOS thread, occurring through an exchange of the bound and non-bound TEA cations (Watanabe et al., Rheol Acta, 28, 110 (2000)), appeared to be strongly suppressed by the preferentially bound TMA cations that effectively blocked the exchanging sites. Indeed, in a range of φTEA ≥ 0.5 where the thermal scission governed the relaxation of the system, the rheological data were well described by a simple model considering this blocking effect.
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Jindong Ren, Osamu Urakawa, Keiichiro AdachiArticle type: Original Article
2004 Volume 32 Issue 4 Pages 161-167
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSDielectric measurements were carried out on two polymer blends consisting of an eco-friendly polymer poly(lactic acid) (PLA) and polyethers: One was PLA/poly(ethylene grycol) (PEG) with molecular weight M of 300 and the other was PLA/poly(propylene glycol) (PPG) with M=1000. The DSC thermograms indicated that PLA/PEG and PLA/PPG were miscible in the range of PLA content above 60 and 75 %, respectively. Corresponding to the thermal data, PLA/PEG and PLA/PPG blends exhibited single dielectric loss peak in the miscible range. The loss curves were much broader than those of the components due to concentration fluctuation. The amplitude of concentration fluctuation was assessed from the temperature dependence of the half width of the dielectric loss curves by assuming the Gaussian distribution of local concentration.
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Hajime Aono, Nobutake Tamai, Daisuke Tatsumi, Takayoshi MatsumotoArticle type: Original Article
2004 Volume 32 Issue 4 Pages 169-177
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSThe effect of mercerization on the cellulose solution was investigated in terms of rheological and dilute solution properties in 8 wt % LiCl/N,N-dimethylacetamide (DMAc). Cotton lint, cotton linter, and dissolving pulp were used for native cellulose samples. Static light scattering (SLS) measurements show that the second virial coefficient, A2, of the cellulose solutions decreased by the mercerization, indicating that the affinity between cellulose and the solvent molecules decreased by the mercerization. A long time relaxation was found only for the mercerized cellulose solution by viscoelastic measurements for semidilute solutions. This indicates that some heterogeneous structures were formed in the mercerized cellulose solution. Some aggregate structures, which have slow decay time, were observed in the 0.5 wt % mercerized cellulose solution by dynamic light scattering (DLS) measurements. According to these results, the low affinity between cellulose and the solvent makes some aggregate structures in the mercerized cellulose solutions in 8 wt % LiCl·DMAc above the overlap concentration.
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Kyoko Hayashi, Yasukazu Ejima, Takeshi Shimizu, Sumiko Kizaki, Shigeo ...Article type: Original Article
2004 Volume 32 Issue 4 Pages 179-187
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSThis study concerns crystallization behavior of crystalline polymers in a phase-separated polymer blend. It might be generally considered that spherulites cannot grow bigger than phase-separated domains. However, it has been confirmed experimentally that it is possible. We found that the same phenomena for blends of LLDPE (linear low density polyethylene) with a rubber polymer. In this study, effects of phase-separated domains on the spherulite growth and the crystallization behavior of LLDPE were studied. For quantitative discussion, we employed a simultaneous measurement technique of synchrotron SAXS/WAXS/Hv-SALS. It was found that the spherulites were 10~20 times lager than the phase-separated domains. It was also found that the long period of crystalline lamellae was smaller than phase-separated domains. Therefore, we suppose that the phase-separated structure has no influence on the fibril growth, which is the fundamental step of spherulites growth. Namely, the fibril growth through a channel of phase-separated crystalline domains enables the overall growth of spherulites. In the meantime, it was found that the index of degree of crystallinity in the LLDPE phase decreased slightly with the blend composition and induction periods of SAXS, WAXS, Hv-SALS in the phase-sepatared blend of LLDPE with a rubbery polymer were longer than those in a neat LLDPE. It was also suggested that nuclear growth was obstructed to some extent by the phase-separated domains. We suppose that nuclei which were not obstructed grew so that spherulites in the phase-sepatared blend sample became bigger than in a neat LLDPE sample.
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Osamu Urakawa, Masaatsu Kido, Keiichiro AdachiArticle type: Original Article
2004 Volume 32 Issue 4 Pages 189-195
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSWe investigated the dielectric normal mode relaxation on diblock copolymers poly(isoprene-block-butadiene) (I-B) with several polyisoprene (PI)/polybutadiene (PB) compositions. Through the dielectric measurements on I-B, we can obtain information about the dynamics of the PI subchain since the PI block is labeled with type-A dipole but PB is not. At the same time, we carried out viscoelastic measurements on the same I-B samples to obtain information of the whole chain motion, especially the longest relaxation times and the plateau moduli. From these viscoelastic and dielectric data, we can directly compare the relaxation spectra of subchains with those predicted by the tube model. From such comparison, we have found that the end part of the chain relaxes faster than the theoretical prediction suggesting extra relaxation mechanisms other than reptation in the dynamics of chain ends.
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Yuichi Masubuchi, Hiroshi Watanabe, Giovanni Ianniruberto, Francesco G ...Article type: Original Article
2004 Volume 32 Issue 4 Pages 197-202
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSMolecular simulations of entangled linear polymers under fast shear flows, based on the primitive chain network model, are performed to investigate relaxation mechanisms of polymers. It is found that the original primitive chain network model incorporating all known molecular mechanisms (i.e., reptation, tube length fluctuation, thermal and convective constraint release, force balance at each binary entanglement), though in good agreement with typical viscosity curves, shows an excessive acceleration of the end-to-end relaxation in the shear-thinning region, inconsistently with dielectric relaxation experiments. Better agreement with data is achieved if the model is implemented so as to account for hidden entanglement appearance (HEA in the following), a mechanism that modifies constraint renewal in the nonlinear range. HEA partly suppresses the acceleration of the end-to-end relaxation, thus predicting more consistent results with dielectric relaxation experiments, without affecting the shear viscosity curve. A possible interpretation of the effect is offered.
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Toshiyuki Shikata, Aiko Sakamoto, Kenji HanabusaArticle type: Original Article
2004 Volume 32 Issue 4 Pages 203-210
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSCreep and creep recovery behavior was investigated for a supramolecular polymeric system consisting of N,N',N"-tris(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide and n-decane. In the linear viscoelastic regime, the system shows behavior well described with a Maxwell element having a set of a relaxation time (τ) and strength (GN). The creep behavior of the system in the linear regime is simple; after showing the instantaneous value (J(0)) equal to the steady state compliance (Je0 = GN−1), creep compliance (J(t)) increases with the elapsed time (t) keeping a proportional constant identical with the reciprocal of the viscosity (η0−1= (τGN) −1). In this regime, creep recovery (JR(t)) reaches a constant value after showing the recoverable compliance (JR = GN− 1). In the nonlinear regime at high shear stresses, the creep behavior is classified into two categories depending on t. In a short time region, the value of J(0) and a viscosity (η(0)) determined from the initial slope of J(t) decrease with increasing shear stress (σ). These mean that the system becomes harder and less viscous with increasing σ. On the other hand, the creep behavior of the system is characterized by the steady state viscosity (ηe) and JR in the steady flow state. The ηe value decreases with increasing σ, and JR exhibits remarkable stepwise increase at a shear rate identical with the reciprocal of τ.
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Takashi Nishino, Akiko Nozawa, Masaru Kotera, Katsuhiko NakamaeArticle type: Original Article
2004 Volume 32 Issue 4 Pages 211-214
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSThe mechanical tensile deformation of Kapton type polyimide (PI) film surface was observed in situ using an atomic force microscope (AFM). From the changes of the AFM images under the loads, the microscopic (5μm×5 μm range), mesoscopic (50μm×50 μm range) and macroscopic (20mm range) surface deformations could be evaluated. The microscopic stress-strain curves with different magnifications were found to coincide one another, which indicates an affine deformation of the PI film. Young's modulus of PI film was obtained as 1.8 GPa from the initial slope of the stress-strain curve by AFM. The film was found to shrunk in the direction perpendicular to the loading axis, and the apparent Poisson's ratio was evaluated as 0.45.
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Hisahiko Kashihara, Masaoki Takahashi, Kenji Urayama, Toshikazu Takiga ...Article type: Original Article
2004 Volume 32 Issue 4 Pages 215-219
Published: 2004
Released on J-STAGE: December 12, 2004
JOURNAL FREE ACCESSWe investigated the influence of viscoelasticity of the domain phase on that of the polymer blend. The polyethylene (PE, matrix phase)/polypropylene (PP, domain phase) blend was used and the viscoelastic change was measured on condition that PP alone crystallizes. The modulus of domain phase was lower than that of matrix phase at first, but was much higher when PP was completely crystalized. The average domain size was almost the same before and after the test. The storage modulus at low frequencies increased more rapidly than that at high frequencies, and then the former decreased and the latter increased continuously. These changes are almost understood by Palierne's emulsion model. Recovery from deformation of domain phase effectively makes long-time viscoelastic relaxation when the modulus of domain phase is close to or lower than that of matrix phase.
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