Dynamic mechanical and dielectric relaxations of polystyrene below the glass temperature

Yano, Okihito; Wada, Yasaku

doi:10.1002/pol.1971.160090409

Cited by 179 publications

(148 citation statements)

References 37 publications

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“…The similarity between reported values for the activation energy of this process (-38-50 kJ/mol) (2,36,(38)(39)(40) and the E,,, values obtained for oxygen diffusion (Table 4) indicate that, at these temperatures, this motion may create the dynamic cavities in polycarbonate that control oxygen transport.…”

Section: Effect Of Temperature On Dmentioning

confidence: 78%

“…(a) Polystyrene Published data obtained from NMR and mechanicaVdielectric relaxation measurements indicate that rotation of the pendant phenyl group in polystyrene is the principal chracteristic motion of the macromolecule in the temperature range -5-85°C (36,37). Reported values for the activation energy of this process are -38 kJ/mol (36,37).…”

Section: Effect Of Temperature On Dmentioning

confidence: 99%

“…Published data obtained from NMR and mechanicaYdielectric relaxation measurements indicate that rotation of the phenyl group in the polycarbonate backbone, along with attendant local segmental conformational changes, is the principal characteristic motion of the macromolecule in the temperature range -5-75°C (2,36,(38)(39)(40). The similarity between reported values for the activation energy of this process (-38-50 kJ/mol) (2,36,(38)(39)(40) and the E,,, values obtained for oxygen diffusion (Table 4) indicate that, at these temperatures, this motion may create the dynamic cavities in polycarbonate that control oxygen transport.…”

Section: Effect Of Temperature On Dmentioning

confidence: 99%

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Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Wang¹,

Ogilby²

1995

Can. J. Chem.

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A recently developed spectroscopic technique was used to determine oxygen diffusion coefficients as a function of temperature for polystyrene and polycarbonate films. Data were recorded at total pressures <300 Torr over the temperature range 5–45 °C under conditions in which argon, helium, and nitrogen, respectively, were copenetrants. In all cases, the presence of the additional gas caused an increase in the oxygen diffusion coefficient. Arrhenius plots of the data yield (a) a diffusion activation barrier, Eact, and (b) a diffusion coefficient, D0, that represents the condition of "barrier-free" gas transport for the temperature domain over which the Arrhenius plot is linear. For all cases examined in both polystyrene and polycarbonate, D0 increased with an increase in the partial pressure of added gas. In polystyrene, the presence of an additional gas did not change Eact. In polycarbonate, Eact obtained in the presence of helium and argon likewise did not differ from that obtained in the absence of the copenetrant. When nitrogen was the added gas, however, a larger value of Eact was obtained. This latter observation is interpreted to reflect the plasticization of polycarbonate by nitrogen. Eact and D0 data are discussed within the context of a model that distinguishes between dynamic and static elements of free volume in the polymer matrix. Keywords: oxygen diffusion, polystyrene, polycarbonate, activation barrier.

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Section: Effect Of Temperature On Dmentioning

confidence: 78%

Section: Effect Of Temperature On Dmentioning

confidence: 99%

Section: Effect Of Temperature On Dmentioning

confidence: 99%

See 1 more Smart Citation

Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Wang¹,

Ogilby²

1995

Can. J. Chem.

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“…At temperatures tens of degrees below T g , the molecular motion of the ␣ relaxation is mostly frozen; 1 only the side-group motions, the ␤ and ␥ relaxations, remain active. These sidegroup motions are usually observed as weak features in dielectric loss spectra 6,7 and are much less understood than the ␣-relaxation mode.…”

Section: Introductionmentioning

confidence: 99%

Rubbing‐induced molecular alignment and its relaxation in polystyrene thin films

Tsang

Xie

Tsui

et al. 2001

J Polym Sci B Polym Phys

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Rubbing-induced molecular alignment and its relaxation in polystyrene (PS) thin films are studied with optical birefringence. A novel relaxation of the alignment is observed that is distinctly different from the known relaxation processes of PS. First, it is not the Kohlrausch-Williams-Watts type but instead is characterized by two single exponentials plus a temperature-dependent constant. At temperatures several degrees or more below the glass-transition temperature (T g ), the relaxation time falls between that of the ␣ and ␤ relaxations. Second, the decay time constants are the same within 40% for PS with weight-average molecular weights (M w 's) of 13,700 -550,000 Da at temperatures well below the sample T g 's, indicating that the molecular relaxations involved are mostly local within the entanglement distance. Nonetheless, the temperature at which the rubbing-induced molecular alignment disappears (T 0 ) exhibits a strong M w dependence and closely approximates the T g of the sample. Furthermore, T 0 depends notably on the thickness of the polymer in much the same way as previously found for the T g of supported PS films. This suggests that the ␣ process becomes dominant near T g . Preliminary spectroscopic studies in the mid-infrared range show a significant degree of bending of the phenyl ring toward the sample surface, with the COC bond connecting the phenyl ring and the main chain tends to lie along the rubbing direction, which indicates that the relaxation is connected with the reorientation of this COC bond. We exclude the observed relaxation, as predominantly a near-surface one, because detailed studies on the effects of rubbing conditions on the degree of molecular alignment indicate that the alignment is not local to the polymer-air surface.

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“…2, we plot m ¼ v 0 Á=r using the reference volume, v 0 ¼ 0:1 ½nm 3 , A ¼ B ¼ 0:5, and l 0 ¼ 43:6 ½nm at 110 C. We take " PEO ¼ 7:5, which is the accepted value for the dielectric constant of PEO [23]. We take " PS ¼ 4; the value reported in literature ranges from 2.6 to 4 [24] but we find the higher value fits the data better. Because we want to compare [10] for the Li½NðSO 2 CF 3 Þ 2 (LiTFSI) system, we perform our fitting using only the data for the TFSI À anion (which has a radius a ¼ 0:381 ½nm), with v 0 1 our only fitting parameter; the fitting yields v 0 1 ¼ À3:6.…”

mentioning

confidence: 99%

Thermodynamics of Ion-Containing Polymer Blends and Block Copolymers

2011

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We develop a theory for the thermodynamics of ion-containing polymer blends and diblock copolymers, taking polyethylene oxide (PEO), polystyrene and lithium salts as an example. We account for the tight binding of Li þ ions to the PEO, the preferential solvation energy of anions in the PEO domain, the translational entropy of anions, and the ion-pair equilibrium between EO-complexed Li þ and anion. Our theory is able to predict many features observed in experiments, particularly the systematic dependence in the effective parameter on the size of the anions. Furthermore, comparison with the observed linear dependence in the effective on salt concentration yields an upper limit for the binding constant of the ion pair. DOI: 10.1103/PhysRevLett.107.198301 PACS numbers: 83.80.Uv, 77.22.Àd, 82.35.Rs, 83.80.Sg There is much current interest in ion-containing polymers as materials for energy applications [1]. Of particular interest for rechargeable battery applications are block copolymers [2][3][4] of an ion-dissolving block, typically polyethylene oxide (PEO), and a nonconducting block such as polystyrene (PS), doped with lithium salts. The lithium ions are complexed with EO groups [5], and together with their counterions, provide the charge carriers [6]. The nonconducting block can be tuned to confer other functions, such as mechanical robustness [3,4,6].Experimentally, the addition of lithium salts has been shown to have significant effects on the order-order and order-disorder transitions in block copolymers [3,7,8]. Among other effects, it is found that the effective parameter characterizing the immiscibility of the two blocks increases linearly with salt concentration [9,10],where is the intrinsic Flory-Huggins parameter for the salt-free system, r is the molar ratio of Li þ ions to EO monomers, and the slope m depends on the anion type. Wanakule et al. [10] found that m decreases with increasing anion radius a. No existing theory describes this behavior. Since the Li þ ions are strongly bound to the EO groups [11], one may consider the PEO with its bound Li þ ions as an effective polyelectrolyte, with the anions acting as the counterions. However, existing theories for diblock copolymers with a charged block and a neutral block [12,13] predict enhanced miscibility between the blocks relative to the uncharged system, opposite to experimental observations; there is also no dependence on the radius of the counterions.The strong binding of Li þ to the EO groups clearly will affect the thermodynamics of PEO-PS diblock copolymers. However, as suggested in Ref.[10] and demonstrated here, a key effect in these ion-containing polymers is the solvation energy of the anions, which has been ignored in all existing theories of ion-containing polymers. An earlier theory developed by one of us [14], taking into account the effects of ion solvation, predicted that adding salts to binary polymer blends can decrease the miscibility between the two polymers. However, that theory assumed the salt ions to be fully dissociated a...

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Dynamic mechanical and dielectric relaxations of polystyrene below the glass temperature

Cited by 179 publications

References 37 publications

Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Rubbing‐induced molecular alignment and its relaxation in polystyrene thin films

Thermodynamics of Ion-Containing Polymer Blends and Block Copolymers

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