The solution and transport of gases in poly(<i>N</i>‐butyl methacrylate) in the glass transition region. I. Absorption‐desorption measurements

Stern, S. A.; Vakil, U. M.; Mauze, G.R.

doi:10.1002/polb.1989.090270213

Cited by 17 publications

(6 citation statements)

References 28 publications

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“…It should be stressed, however, that not all the polymers experience a sharp increase in the value of the diffusion coefficient in the glass−rubber transition. For some polymers, Arrhenius plots of the diffusion coefficient present discontinuities in the glass transition region which have been linked to high values of the Δα/α g ratio, where α g is the thermal expansion coefficient at the glassy state and Δα is the change of the thermal expansion coefficient at T g . − These discontinuities have not been observed for those polymers in which Δα/α g < 1. Accordingly, whether the values of D evolve smoothly with temperature in the transition from the glassy to the rubbery state depends on the Δα/α g ratio …”

Section: Discussionmentioning

confidence: 99%

Experimental and Simulation Studies on the Transport of Argon through Poly(pentaerythritoltribenzoate acrylate)

et al. 1998

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This work reports the permeation of argon through membranes prepared from poly(pentaerythritoltribenzoate acrylate) (PPTBA) (IUPAC name poly[1-(3-benzoyloxy-2,2-dibenzoyloxymethylpropyloxy)-2-propen-1-one]). The permeation measurements were performed in the vicinity of the glass transition temperature of the membranes (48 °C). The permeation coefficient only shows a slight dependence on temperature in the glassy state, but it undergoes a sharp increase with temperature in the rubbery state. The results for the diffusion coefficient do not show a definite temperature dependence in the glass−rubber transition. As expected, the solubility of the gas in the membrane is higher in the rubbery state than in the glassy state. The diffusion coefficient was calculated theoretically by using the Transition-State Approach which assumes that the diffusant path is independent of the structural relaxations in the polymer matrix. Reasonably good agreement between the simulated and the experimental values of the diffusion coefficient was obtained in the range of temperatures from 40 to 60 °C in which the measurements were performed.

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Section: Discussionmentioning

confidence: 99%

Experimental and Simulation Studies on the Transport of Argon through Poly(pentaerythritoltribenzoate acrylate)

et al. 1998

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“…Table 5 ag (> 1.8) are shown by poly(viny1 acetate) (PVAc) (Meares, 1954(Meares, , 1957 and poly(ethy1ene terephthalate) (PET) (Michaels et al, 1963;Koros and Paul, 1978) for which discontinuities in the glass transition regions are observed. In contrast, poly(ethy1 methacrylate) (Stannett and Williams, 1965) and poly(n-butyl methacrylate) (Aharoni, 1973;Stern et al, 1989), which have much lower values of A d a , (near 0.6), show no discontinuities. There was insufficient information to pass judgment on whether a discontinuity would manifest itself in a polymer with a A d a , value between 1.8 and 0.6.…”

Section: Discontinuities Of Transport Properties In the Glass Transitmentioning

confidence: 90%

“…We therefore speculate that the lower bound of the A d a y I values for discontinuities to be observed is close to unity for amorphous polymers. A different explanation was proposed by Stern (1989) to explain the discontinuity effect in the glass transition region.…”

Section: Discontinuities Of Transport Properties In the Glass Transitmentioning

confidence: 94%

“…The dependence of D on temperature for various gas/polymer systems has been studied in the Tg region of the polymers by a number of investigators (Meares, 1954(Meares, , 1957Toi et al, 1983;Kumins and Roteman, 1961;Stannett and Williams, 1965;Koros and Paul, 1978;Stern et al, 1989). Some investigators have reported discontinuities in plots of log D vs. 1/T for some gases in a number of polymers in the glass transition regions.…”

Section: Discontinuities Of Transport Properties In the Glass Transitmentioning

confidence: 99%

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Transport of gases in miscible polymer blends above and below the glass transition region

Li¹,

Hsu²,

Kwei³

et al. 1993

AIChE Journal

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The study of diffusion and permeation of methane, nitrogen, and helium in miscible blends of poly(styrene-stat-acrylonitrile) (PSAN) and poly(methy1 methacrylate) (PMMA) at 35-140°C shows that permeation coefficients (P) of helium followed the linear logarithmic mixing rule. Positive deviations from the linear logarithmic mixing rule were observed for permeation and diffusion coefficients (0) of methane and nitrogen below the glass transition temperature (Tg). The deviations decreased with increasing temperature and disappeared above Tr The experimental results were analyzed by free volume and activated state theories. The Arrhenius plots of log D or log P us. the reciprocal of temperature exhibited discontinuities in the glass transition region for all gases and blend compositions. The discontinuities are caused by large thermal expansion coefficient differences between the rubbery and glassy states of PSAN and PMMA. The sorption of methane in 50150 PSAN/ PMMA has dual-mode characteristics below Tr Experimental Studies MaterialsPoly(styrene-stat-acrylonitrile) (PSAN), containing 30 wt. 070 of acrylonitrile and poly(methy1 methacrylate) (PMMA) were obtained from Scientific Polymer Products. The weightaverage molecular weight of PSAN is 185,000 as supplied by the manufacturer. The weight-average molecular weight of PMMA is 93,000 and the number-average molecular weight 46,000.The glass transition temperatures ( T,) of the polymers were measured by the use of a Perkin Elmer 7 Series differential scanning calorimeter (DSC). DSC experiments were carried

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“…Poly(n-butyl methacrylate) (PBMA). Average diffusion coefficient for n-butane determined from the initial slope of sorption/desorption curves vs. n-butane concentration at different temperatures T and for different PBMA membrane thicknesses δ[89Ste].…”

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confidence: 99%

9 Diffusion in glassy and semicrystalline polymers

Faupel¹,

Kroll²

Landolt-Börnstein - Group III Condensed Matter

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Wide attention has been paid in recent years to diffusion through polymeric materials for its interesting applications in various technological fields [91Vie]. Examples are permselective membranes for separation of gases, vapors and liquids, food packing, protective coatings and controlled drug delivery systems. Moreover, diffusion studies have provided valuable information on the structure of polymers and timedependent changes in the glassy state. Particularly gas molecules were often used as structure-sensitive probes of variable size.Since this volume is concerned with diffusion in solids, the present chapter covers diffusion in glassy polymers and semicrystalline polymers with a glassy amorphous phase. The diffusion behavior of semicrystalline polymers is essentially governed by the amorphous phase. For crystalline polymers the reader is referred to Chap. 8 on molecular solids.Diffusion characteristics of polymers can be markedly affected by the presence of additives, such as plasticizers and stabilizers, and by residual solvent. In glassy polymers the polymer molecular weight generally has no influence unless it is very low [82Toi2]. The non-equilibrium nature of the glassy state gives rise to a history dependence of transport properties and the appearance of local inhomogenities [91Vie, 94Pet, 89Kor]. The latter are produced by the residual mobility of different frozen chains, which are unable to relax to thermal equilibrium because of inhibited segmental motions. The influence of history on current and future performance of glassy polymers is well documented for thermal and mechanical treatment as well as for processing conditions. Furthermore, many studies have reported penetrant-induced history-dependent effects, often termed conditioning in connection with transport in glassy polymers. History also affects the orientation of molecules and the crystallinity of semicrystalline polymers. History effects manifest themselfs in time-dependent and hysteretic behavior. For instance, structural relaxation of glassy polymers, which is accompanied by annealing of excess volume, may lead to a marked decrease of penetrant diffusivities [90Ehl, 94Zha]. On experimental time scales diffusivities finally approach a time-independent value being characteristic of the well relaxed glassy state. An example of penetrant-induced conditioning and hysteresis is the exposure of glassy polymers to relatively high CO 2 pressures, which induces a volumetric expansion effect. A substantial increase in excess volume persists long after the penetrant has been removed. No hysteretic effects are usually observed, even at high pressure in the MPa range, for gases such as He, N 2 and even CH 4 [89Kor]. The lower condensability, and hence lower solubility of these supercritical gases, is presumable responsible for their lack of conditioning capability.In view of the abovementioned complications it is obvious that diffusion data in glassy polymers are often not very meaningful without detailed information on sample preparation and history. ...

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The solution and transport of gases in poly(N‐butyl methacrylate) in the glass transition region. I. Absorption‐desorption measurements

Cited by 17 publications

References 28 publications

Experimental and Simulation Studies on the Transport of Argon through Poly(pentaerythritoltribenzoate acrylate)

Experimental and Simulation Studies on the Transport of Argon through Poly(pentaerythritoltribenzoate acrylate)

Transport of gases in miscible polymer blends above and below the glass transition region

9 Diffusion in glassy and semicrystalline polymers

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