Birefringence of amorphous polymers. 1. Dynamic measurement on polystyrene

Inoue, Tadashi; Okamoto, Hiroyuki; Osaki, Kunihiro

doi:10.1021/ma00020a029

Cited by 196 publications

(282 citation statements)

References 10 publications

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“…39,40 Thus, it is not clear what M SC corresponds to for solution data, although one research group has found that for a PS melt M SC is approximately the same as the Kuhn segment molecular weight. 41,42 Solution data may provide an M SC that does not reflect chain stiffness but rather reflects chain-segment mobility limitations imposed by the timescales for the dynamics of the solvating environment, as subsequently discussed.…”

Section: Resultsmentioning

confidence: 99%

“…However, VE measurements on PS melts suggest a substantially greater flexibility: Gray et al 43 report VE data from 3500 and 10,200 molecular weight PS at 123°C that they fit with the BSM obtaining N ϭ 7 and 20, respectively (Rouse model, i.e., h* ϭ 0), which gives M SC ϭ 500 or 510. In addition, Inoue et al, 41 reporting on elongational VE measurements on a 15,000 molecular weight PS, obtained M SC ϭ 900 from the highfrequency limit of their VE data. The evidence from both groups points to a size of the BSM subchain that is significantly smaller than that obtained from fits to PS solution data.…”

Section: Resultsmentioning

confidence: 99%

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Apparent relaxation‐time spectrum cutoff in dilute polymer solutions: An effect of solvent dynamics

Peterson

Echeverría

Hahn

et al. 2001

J Polym Sci B Polym Phys

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ABSTRACT:The apparent short time cutoff of the relaxation-time spectrum at surprisingly long times for polymers in solution is a well known but not yet understood observation. To elucidate its origins we revisit viscoelastic and oscillatory flow birefringence data for solutions and melts of two linear polymers (polystyrene and polyisoprene) and present new measurements of oscillatory flow birefringence of the latter. Previous measurements have suggested that the "flexibility" of both polymers in solution is smaller than in the melt on the basis of the breadth of the relaxation-time spectrum of the solution as compared with that of the melt. Our new measurements have explored a higher effective frequency range than was previously possible. This has allowed us to observe the effect of the rotational relaxation time of the solvent on the dynamics of the solution at high frequencies. To obtain the polymer global motion contribution, one now needs to subtract from the solution properties a frequencydependent complex solvating environment contribution. We show that the decrease in apparent "flexibility" for solutions arises from the presence of a solvent that exhibits a rotational relaxation time and thus simple viscoelastic behavior somewhat near the frequency window of the experiment. Although recent predictions of a model for a chain in a solvent with a single relaxation time are in qualitative agreement with our results, our data suggest that the solution results may reflect the influence of solvent on the development of the "entropic spring" forces at short times.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Apparent relaxation‐time spectrum cutoff in dilute polymer solutions: An effect of solvent dynamics

Peterson

Echeverría

Hahn

et al. 2001

J Polym Sci B Polym Phys

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“…This study focuses on the stress in such a long time scale. At shorter times, the glassy stress is not negligible as noted from experiments 11,12) as well as Brownian dynamics simulation, 13) and the modified stress optical rule (MSOR) 11,12) holds instead of SOR (Eq. (7)).…”

Section: Stress-optical Rulementioning

confidence: 99%

Revisit the Stress-Optical Rule for Entangled Flexible Chains: Overshoot of Stress, Segmental Orientation, and Chain Stretch on Start-up of Flow

Watanabe

Inoue

2015

J. Soc. Rheol., Jpn

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For flexible polymers, the deviatoric parts of the stress and optical anisotropy tensors, with the latter reflecting the orientational anisotropy of the monomeric segments, are proportional to each other. This proportionality, known as the stress-optical rule (SOR), is valid not only in the linear viscoelastic regime but also in the moderately nonlinear regime, given that the chain is not highly stretched and is free from the finite extensible nonlinear elasticity (FENE) effect. On start-up of flow in such a moderately nonlinear regime, the chain exhibits an overshoot of the shear stress and thus of the shear component of the segmental orientational anisotropy. Nevertheless, it was not clearly understood whether this overshoot is associated with an overshoot of chain stretch. This study revisited SOR to conduct a simple analysis for this problem. It turned out that the orientational anisotropy of subchains overshoots but the subchain stretch (identical to the chain stretch) does not when the shear stress overshoots in the moderately nonlinear regime.

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“…Birefringence technique has been used to study the molecular dynamics in glassy linear polymers, and the modified stress-optical rule (MSOR) proposed by Inoue 13) has successfully been used to analyze birefringence changes of glassy linear polymers. [13][14][15][16][17][18][19][20][21][22] The MSOR is considered to be a powerful tool also for epoxy glass to study its plastic deformation mechanism.…”

Section: )mentioning

confidence: 99%

Molecular Cooperativity in Large Deformation and Subsequent Structural Relaxation for Epoxy Glass

Kawakami

2007

J. Soc. Rheol., Jpn

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In the present article, results from our recent studies on effects of chemical crosslinks in epoxy glass subjected to large deformation and subsequent aging under strain are reviewed. Bis-A type epoxy monomer was cured with DDM to form a sample with a crosslinked network structure. The monomer was also polymerized with aniline to form another sample with an uncrosslinked linear molecular structure. First, change in birefringence in the course of elongation was measured, and the modified stress-optical rule was applied to the experimental results. For the crosslinked sample, both internal potential and entropy changed in a small strain range. On the other hand, for the linear molecular sample only internal potential increased in a small strain range. Another series of results was obtained through thermomechanical experiments with largely deformed specimens, and the obtained results indicated that chemical crosslinks forced more rubbery strain to recover at temperatures below T g . From these studies it was proposed that chemical crosslinks in epoxy glass enhance cooperativity between molecular motions taking place in deformation as well as in subsequent retardation process. Such an effect of chemical crosslinks was also observed in the crosslinked sample under the state of aging under strain.

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Birefringence of amorphous polymers. 1. Dynamic measurement on polystyrene

Cited by 196 publications

References 10 publications

Apparent relaxation‐time spectrum cutoff in dilute polymer solutions: An effect of solvent dynamics

Apparent relaxation‐time spectrum cutoff in dilute polymer solutions: An effect of solvent dynamics

Revisit the Stress-Optical Rule for Entangled Flexible Chains: Overshoot of Stress, Segmental Orientation, and Chain Stretch on Start-up of Flow

Molecular Cooperativity in Large Deformation and Subsequent Structural Relaxation for Epoxy Glass

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