Immobilization influence on the water sorption and diffusion in poly(3-hydroxybutyrate)

The temperature dependency of water vapor sorption and diffusion in poly(3-hydroxybutyrate) (PHB) was studied for the first time. Equilibrium sorption and diffusion kinetics were determined by a quartz McBain's vacuum microbalance technique in the temperature range of 303–333 K. A probability of water molecule interaction with the polymer matrix was analyzed for wet PHB films by FTIR spectroscopy technique. Sorption isotherms are interpreted as the solution of free water molecules estimated by the Flory–Huggins equation and the sorption of water molecules immobilized on the carbonyl groups of PHB. The immobilization effect was described by a Langmuir-type equation. The dependency of diffusivity on water concentration was described in the frames of Fujita's immobilization model in which the growing function D_w versus C_w characterized the filling degree of carbonyl groups as sites of immobilization in the polymer. Enthalpy of free water sorption (12 kJ/mol) and water immobilization (42 kJ/mol), as well as the activation energy of water diffusion coefficients (71 kJ/mol), in noncrystalline areas of PHB were determined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 981–985, 1999     

Sorption and diffusion of n-alkanes into bromobutyl rubber membranes

Sorption and diffusion of n-alkanes into bromobutyl rubber membranes were investigated in the temperature interval 25–60°C by a sorption gravimetric method. The Fickian diffusion equation was used to calculate the diffusion coefficients, which were dependent on the size of the alkanes, their interactions with the chain segments of the polymer and temperature. The diffusion coefficients varied from 0.34×10^?7 cm²/s (n-hexadecane) to 9.94×10^?7 cm²/s (n-hexane). The activation energy for diffusion varied from 14kJ/mol (n-hexane) heptane to 2.0kJ/mol for n-hexadecane. The sorption/swelling results are discussed in terms of first and second order kinetic equations. The molar mass between chain-entanglement-crosslinks was estimated from swelling data. The experimental and calculated results showed a systematic dependence on the increasing size of the alkanes. None of the solvents showed any degradative effects on the polymer.     

Solubilities and diffusivities of water vapor in poly(methylmethacrylate), poly(2-hydroxyethylmethacrylate), poly(N-vinyl-2-pyrrolidone) and poly(acrylonitrile)

Sorption and diffusion data were obtained for water vapor in four different polymers: poly (methylmethacrylate) (PMMA), poly (2-hydroxyethylmethacrylate) (PHEMA), poly (N-vinyl-2-pyrrolidone) (PVP) and poly (acrylonitrile) (PAN) at 35 °C using a gravimetric sorption method. Highest sorption was for PVP, followed by PHEMA. PMMA and PAN sorbed very little water. All the polymers exhibit a BET type III sorption isotherm; the large upturn at high activity for PVP and PHEMA is probably due to plasticization of the polymers by water vapor. Sorption data were interpreted using Flory-Huggins theory and the Zimm and Lundberg cluster integral.Fickian diffusion is observed for PHEMA. For PVP, the fractional uptake M_t/M_∞ is linear with the square root of the time up to M_t/M_∞=0.6−0.8 for all water activities a_w, but it shows a clear water sorption overshoot at a_w=55.3% and a_w=72.1%, probably due to macromolecular relaxation. PMMA sorption kinetics is also characterized by a maximum in the water uptake. The diffusion coefficient increases significantly with water concentration for PVP and PHEMA, weakly for PMMA, but it is independent of concentration for PAN.     

Competitive sorption of water vapor and CO2 in photocrosslinked PVCA film for a capacitive‐type humidity sensor

The sorption behavior of water vapor and CO₂ gas in photocrosslinked poly(vinyl cinnamate) (PVCA) film was examined at 30°C under atmospheric pressure. Both the water sorption isotherm and the CO₂ sorption isotherm obtained with quartz crystal microbalance (QCM) method obeyed the simple Langmuir's equation. Water vapor/CO₂ mixed‐gas sorption isotherms were also obtained. Total amount of sorbed mixed gases was clearly influenced by the partial pressure of water vapor (p_w) and CO₂ gas (p_c) in the atmosphere. A modified Langmuir's equation based on a dual‐site model was employed for predicting the competitive adsorption isotherm, and the isotherm was clearly described by the equation. The theoretically estimated amount of adsorbed water at the constant p_w decreased slightly with increasing p_c. The effect of this phenomenon on the sensitivity of the capacitive‐type relative humidity sensor was examined. As expected, the electrical capacitance of the sensor at the constant relative humidity decreased because of the coexistence of CO₂ gas. However, the influence was quite small in the CO₂ concentration range in the ordinary environment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 401–407, 2002     

Molecular transport of n‐alkanes into PU/PBMA interpenetrating polymer network systems

The methylene diisocyanate (MDI) and toluene diisocyanate (TDI) based polyurethane/polybutyl methacrylate (PU/PBMA‐50/50) interpenetrating polymer network (IPN) membranes have been prepared. The molecular migration of n‐alkane penetrants such as hexane, heptane, octane, nonane, and decane through PU/PBMA (50/50) membranes has been studied at 25, 40, and 60°C using a weight gain method. From the sorption results, diffusion (D) and permeation (P) coefficients of n‐alkane penetrants have been calculated. Molecular migration depends on membrane‐solvent interactions, size of the penetrants, temperature, and availability of free volume within the membrane matrix. Attempts have been made to estimate the parameters of an empirical equation and these data suggest that molecular transport follows Fickian mode. From a study of temperature dependence of transport parameters, activation energy for diffusion (E_D) and permeation (E_P) have been estimated from the Arrhenius relation. Furthermore, sorption results have been interpreted in terms of enthalpy (ΔH) and entropy (ΔS) of sorption. The liquid concentration profiles have been computed using Fick's equation with appropriate initial and boundary conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 739–746, 2003     

Efficient Utilization of Crude Glycerol as Fermentation Substrate in the Synthesis of Poly(3-hydroxybutyrate) Biopolymers

One refined and two crude glycerol (from biodiesel production) samples were utilized to produce poly(3-hydroxybutyrate) (PHB) by Pseudomonas oleovorans NRRL B-14682. A batch culture fermentation protocol including 1% glycerol and an aeration rate of 3 standard liters per minute proved best for PHB synthesis (av. yield = 1.0 ± 0.2 g/L at 48 h) and efficient glycerol utilization. PHB molecular weights decreased as MeOH concentration increased. Refined glycerol resulted in PHB polymers with number average molecular weights (M _n) of 314,000 g/mol which decreased by 17 and 90% as MeOH media concentrations increased to <0.005 and 0.85%, respectively. Proton (¹H) NMR demonstrated the presence of glycerol- and methoxy-based end-capping, which was confirmed by ¹H diffusion experiments (DOSY analyses). NMR diffusion analyses of the PHB polymers established their diffusivities, and confirmed that their relative molecular sizes were dependent on the impurities in the glycerol. In addition, DOSY analyses indicated that each end-capped PHB polymer and the glycerol or methoxy groups bound to it had the same diffusion constants, demonstrating that they migrated together as covalent complexes. Non-covalent complexation was eliminated by physically mixing free glycerol with PHB synthesized from oleic acid; their respective diffusivities were notably faster.     

Influence of a monomeric plasticizer on the water-sorption behaviour of food-grade plastics packaging materials

The interaction of water with poly(vinylchloride) and poly(vinylidene chloride-vinylchloride) (p(VdC-VC)) plasticized with different amounts of a monomeric plasticizer (dioctylphthalate) has been studied using inverse gas chromatography. The present work was focused on the effect of temperature and plasticizer content on the water sorption behaviour of these plastics packaging materials. Values for thermodynamic parameters such as Gibb's free energy (ΔG_s), enthalpy (ΔH_s), entropy (ΔS_s) and activity coefficient (γ) corresponding to sorption of water by the polymers have been calculated using chromatographic retention data. It was found that the sorption of water vapours increases with increasing the amount of plasticizer and decreases with increasing temperature. The Van Deemter equation was found to be applicable to these systems and was used to determine diffusion coefficients and activation energies for diffusion. Diffusion coefficient values increase with increasing amounts of plasticizer and they also increase with increasing temperature; this latter increase is accompanied by a decrease in the activation energy for diffusion. Present results were also compared to our own previous data, using a polymeric plasticizer.     

Removal of phosphate anions from aqueous solutions using polypyrrole‐coated sawdust as a novel sorbent

This work was focused on the removal of phosphate ions using polypyrrole‐coated sawdust as a novel cost‐effective sorbent. The phosphate uptake followed the Langmuir sorption isotherm, and the sorption capacity at 20, 35, and 50°C was found to be 17.33, 23.41, and 30.39 mg/g, respectively; this indicated favorable sorption at higher temperatures. The kinetic uptake data were modeled with the Lagergren equation, first‐order and second‐order kinetic models, and the simple Elovich model. The results indicated that the Lagergren model best described the uptake data. The intraparticle diffusion coefficient, as determined for 250–211‐ and 630–600‐μm sorbent particles at 20°C, was found to be 287.3 × 10^?2 and 228.3 × 10^?2 mg g^?1 min^?1, respectively. The intraparticle diffusion was also confirmed with the Bangham equation. The sorption mean free energy, calculated with the Dubinin–Radushkevich equation, was found to be 10.98 kJ/mol, thus confirming an ion‐exchange regulated sorption process. The positive value of the enthalpy change (i.e., 4.23 kJ/mol) confirmed the endothermic nature of the sorption process. The negative values of the change in the standard free energy were indicative of the spontaneous nature of the sorption process. Finally, the activation energy of the sorption process for 250–212‐μm particles, determined with the Arrhenius equation, was found to be 41.68 J/mol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Modification via preparation for poly(3‐hydroxybutyrate) films: Water‐transport phenomena and sorption

The effect of the preparation technique on the sorption–diffusion parameters of poly(3‐hydroxybutyrate) (PHB) films was studied. The films formed by a single‐stage technique have an axial texture of the crystalline phase, with the polymer chain oriented predominantly perpendicularly to the film plane. Moreover, the crystallites in PHB are preferably ordered in stacks in the course of diffusion; the alignment of the crystallites noticeably decreases the “sites” of PHB (polar groups) which are accessible to water molecules. As a result, the sorption capacity decreases but the rate of diffusion increases. On the contrary, PHB films prepared by a two‐stage technique are characterized by a poor ordering of crystallites without texture organization. Here, the sorption/immobilization on the polar groups of PHB is increased, but diffusivities are decreased. Concentration dependencies of the water‐diffusion coefficient are discussed. Additional information on the existence of protein impurities in the PHB samples obtained by the above two preparation techniques was obtained by FTIR spectroscopy and H–D exchange methods. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 475–480, 2000     

Preparation of zeolite‐incorporated poly(dimethyl siloxane) membranes for the pervaporation separation of isopropyl alcohol/water mixtures

ZSM‐5 zeolite‐incorporated poly(dimethyl siloxane) membranes were prepared, and the molecular dispersion of the zeolite in the membrane matrix was confirmed with scanning electron microscopy. After the swelling of the membranes was studied at 30°C, the membranes were subjected to the pervaporation separation of isopropyl alcohol/water mixtures at 30, 40, and 50°C. The effects of the zeolite loading and feed composition on the pervaporation performances of the membranes were analyzed. Both the permeation flux and selectivity increased simultaneously with increasing zeolite content in the membrane matrix. This was examined on the basis of the enhancement of hydrophobicity, selective adsorption, and the establishment of molecular sieving action. The membrane containing the highest zeolite loading (30 mass %) had the highest separation selectivity (80.84) and flux (6.78 × 10^?2 kg m^?2 h^?1) at 30°C with 5 mass % isopropyl alcohol in the feed. From the temperature dependence of the diffusion and permeation values, the Arrhenius activation parameters were estimated. A pure membrane exhibited higher activation energy values for permeability (E_p) and diffusivity (E_D) than zeolite‐incorporated membranes, and signified that permeation and diffusion required more energy for transport through the pure membrane because of its dense nature. Obviously, the zeolite‐incorporated membranes required less energy because of their molecular sieving action, which was attributed to the presence of straight and sinusoidal channels in the framework of the zeolite. For the zeolite‐incorporated membranes, the activation energy values obtained for isopropyl alcohol permeation were significantly lower than the water permeation values, and this suggested that the zeolite‐incorporated membranes had higher selectivity toward isopropyl alcohol. The E_p and E_D values ranged between 21.81 and 31.12 kJ/mol and between 15.27 and 41.49 kJ/mol, respectively. All the zeolite‐incorporated membranes exhibited positive values of the heat of sorption, and this suggested that the heat of sorption was dominated by Henry's mode of sorption. sorption. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1377–1387, 2005     

Surface Diffusion of Oxygen Transport Membrane Materials Studied by Grain‐Boundary Grooving

Mass transport mechanism responsible for grain‐boundary grooving during thermal annealing of polished ceramics of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3‐δ (BSCF) and La₂NiO_4+δ (LN) was revealed by atomic force microscopy. Surface diffusion mechanism was confirmed for both materials by the evolution of the grain‐boundary width (w) with annealing time (t), and the surface diffusion coefficient was determined from the slope of w versus t^1/4 following the theory by Mullins. An Arrhenius temperature dependence of the surface diffusion was observed, and the activation energy was determined to be 220 ± 30 and 450 ± 30 kJ/mol, respectively, for BSCF and LN. The surface diffusion data are discussed with respect to similar data for other oxide materials and cation and oxygen anion diffusion in BSCF and LN. Finally, the dihedral angle for both LN and BSCF was determined, and these are typical in the range reported for other oxide materials.     

Water Sorption,Glass Transition,and Microstructures of Refractance Window– and Freeze-Dried Mango (Philippine “Carabao” Var.) Powder

Water sorption isotherms, glass transition, and microstructures of Refractance Window (RW)– and freeze-dried Philippine “Carabao” mango powders were investigated. Water sorption isotherms were developed by the isopiestic method, while thermal transition of the powders, at various water activities (a _w  = 0.11–0.86), was determined using differential scanning calorimetry (DSC). The sorption isotherms of RW- and freeze-dried (FD) mango powders exhibited a type III sigmoidal curve, showing higher and lower adsorption capacities above and below 0.5 a _w , respectively. A significant difference (p < 0.05) in water content of RW- and freeze-dried mango powders for equivalent water activities was obtained above 0.5 a _w . The onset glass transition temperature (T _gi ) of RW- and freeze-dried mango powder solids decreased as the water content increased. There were no significant differences (p ≥ 0.05) in T _gi of RW- and freeze-dried mango powder solids at constant water activities, except for a _w  = 0.86. Microscopic examination of mango powders indicated that freeze-dried mango powders exhibited greater surface area and porosity in comparison to RW-dried mango powders.     

Pervaporation membranes from natural rubber latex grafted with poly(2‐hydroxyethyl methacrylate) (NR‐g‐PHEMA) for the separation of water–acetone mixtures

NR‐graft‐PHEMA latexes were synthesized by the use of graft emulsion polymerization. By increasing the HEMA monomer concentration, we found that the grafting percentage (GP) also increased. In addition, GP increased significantly at low initiator concentrations before it leveled off at moderate concentrations, and a slight decrease was observed at high initiator concentrations. NR‐g‐PHEMA latexes were prepared as pervaporation membranes for the separation of water–acetone mixtures. From the equilibrium swelling, the nonideal behavior of membrane swelling in water–acetone mixtures was found such that there appeared the maximum swelling degree at a certain concentration of liquid mixtures. Moreover, the water concentration at maximum swelling shifted to high water concentration with increasing amount of graft‐PHEMA. The sorption study suggested the preferential sorption of water on the membranes. Also, the sorption isotherms implied that there was a coupling between water and acetone molecules. Pervaporation separation of water–acetone mixtures was studied with NR‐g‐PHEMA membranes. As the feed water concentration increased, the partial water fluxes increased in contrast to the partial fluxes of acetone. From the permeation ratio, θ_w, the strong coupling of acetone on the water transport was observed, particularly for the membrane with high graft‐PHEMA under acetone‐rich conditions. As the feed temperature increased, the total permeation across the membranes was enhanced. The partial fluxes of water and acetone as a function of temperature followed the Arrhenius relationship by which the activation energies for permeation were estimated as 3.53 kJ/mol for water and 21.95 kJ/mol for acetone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Sorption of propane in poly(ethyl methacrylate) near Tg

The sorption of propane in poly(ethyl methacrylate) was investigated above and below the polymer T_g and the dual-mode sorption model parameters were evaluated. The Langmuir capacity decreased as the temperature was raised to T_g and the apparent Henry's law constant exhibited a discontinuity at T_g. The enthalpy of microvoid filling ΔH_H is more exothermic than the enthalpy of dissolution at T < T_g by about 8 kJ/mol.     

Diffusion coefficient and equilibrium solubility of water molecules in biodegradable polymers

The diffusion coefficient and solubility of water molecules were measured in polyglycolide (PGA), poly(L ‐lactide) (PLLA), poly[(R)‐3‐hydroxybutyrate] (PHB), poly(ϵ‐caprolactone) (PCL), and Skygreen^R (SG). The diffusion coefficient and equilibrium solubility decreased in the order SG > PCL > PLLA > PHB > PGA and PGA > SG > PLLA > PHB > PCL, respectively. The diffusion coefficient and solubility of water at low sorption temperature in PHB varied according to the initial crystallinity of the matrix polymer even though crystallization of PHB molecules took place during the sorption experiment. In contrast, the amorphous PLLA and the crystalline PLLA showed an almost identical diffusion coefficient and solubility of water, in spite of the fact that the amorphous PLLA remained practically amorphous during the whole sorption procedure. A strong correlation existed between the water solubility and the surface tension or contact angle of the polymer matrix. The water diffusivity in PGA was almost 2 orders of magnitude lower while water was more soluble in PGA with a lower heat of sorption than that corresponding to the other more hydrophobic polymers, indicating that the transport of water molecules in PGA followed the solution–diffusion model. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1716–1722, 2000     

Pervaporation separation of water–acetic acid mixtures through NaY zeolite‐incorporated sodium alginate membranes

The pervaporation (PV) separation and swelling behavior of water–acetic acid mixtures were investigated at 30, 40, and 50°C using pure sodium alginate and its zeolite‐incorporated membranes. The effects of zeolite loading and feed composition on the pervaporation performance of the membranes were analyzed. Both the permeation flux and selectivity increased simultaneously with increasing zeolite content in the polymer matrix. This was discussed on the basis of a significant enhancement of hydrophilicity, selective adsorption, and molecular sieving action, including a reduction of pore size of the membrane matrix. The membrane containing 30 mass % of zeolite showed the highest separation selectivity of 42.29 with a flux of 3.80 × 10^?2 kg m^?2 h^?1 at 30°C for 5 mass % of water in the feed. From the temperature dependency of diffusion and permeation data, the Arrhenius activation parameters were estimated. The E_p and E_D values ranged between 72.28 and 78.16, and 70.95 and 77.38 kJ/mol, respectively. The almost equal magnitude obtained in E_p and E_D values signified that both permeation and diffusion contribute equally to the PV process. All the membranes exhibited positive ΔH_s values, suggesting that the heat of sorption is dominated by Henry's mode of sorption. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2101–2109, 2004     

Sorption Isotherms and Drying Characteristics of Tomato Peel Isolated from Tomato Pomace

Tomato peel was separated from pomace by sedimentation and dried in cabinet and fluidized-bed dryer at 50–70°C using 4–12 kg/m²tray load. The drying of tomato peel took place under the falling rate period and the drying behavior was well described by Page's model with coefficient of determination greater than 0.99 and standard error of 0.003–0.016. A fluidized-bed dryer was much more efficient than a cabinet dryer to dry tomato peel. The moisture adsorption isotherms of tomato peel were obtained by equilibrating above saturated salt solutions of known a _w (0.113–0.92) at 20–60°C. The data were analyzed using fifteen sorption models based on coefficient of determination, standard error, and residual plots. Modified Henderson was the best model for tomato peel with coefficient of determination >0.99, standard error <0.210, and a scattered residual plot. The net isostearic heat of sorption, estimated using the Clausius-Clapeyron equation, was 0.74–23.23 kJ/mol at 2.0–2.5% moisture content (dry basis).     

Interaction of crosslinked ethylene–propylene–diene terpolymer blends with chlorinated organic penetrants

The sorption and diffusion of halogenated hydrocarbon penetrants through different ethylene–propylene–diene terpolymer (EPDM) blends, such as EPDM/natural rubber, EPDM/bromobutyl rubber, and EPDM/styrene butadiene rubber (50/50 w/w), were studied. The diffusion coefficient of halogenated penetrants fell in the range 1.5–14.52 × 10^?7 cm²/s in the temperature range of 25–60°C. Transport data were affected by the nature of the interacting solvent molecule rather than its size and also by the structural variations of the EPDM blends. 1,2‐Dichloroethane showed a lower mass uptake compared to other penetrants. The temperature dependence of the transport coefficient was used to estimate the activation parameters, such as the activation energy of diffusion (E_D) and the activation energy of permeation (E_p) from Arrhenius plots. The activation parameters for E_D of aliphatic chlorinated organic penetrants was in the range 7.27–15.58 kJ/mol. These values fell in the expected range for rubbery polymers, well above their glass‐transition temperature. Also, the thermodynamic parameters, such as enthalpy and entropy, were calculated and fell in the range 2–15 kJ/mol and 3–54 J/mol/K, respectively. Both first‐ and second‐order transport kinetics models were used to investigate the transport kinetics, and first‐order kinetics were followed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1366–1375, 2003     

Water sorption kinetics in light‐cured poly‐HEMA and poly(HEMA‐co‐TEGDMA); determination of the self‐diffusion coefficient by new iterative methods

The present investigation is concerned with the determination of self‐diffusion coefficient (D) of water in methacrylate‐based biomaterials following Fickian sorption by two new methods: the Iterative and the Graphical methods. The D value is traditionally determined by means of the initial slope of the corresponding sorption curve and the so‐called Stefan's approximation. The proposed methods using equations without approximations and data resulting from the whole sorption range reach to accurate values of D, even when the sorption curve does not present an initial linear portion. In addition to D, the Graphical method allows the extrapolation of the mass of the sorbed water at equilibrium (M_∞), even when the equilibrium specimen's mass fluctuates around its limited value (m_∞). The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable. The obtained D values compared with those determined by means of the Stephan's method revealed that the proposed methods provide more accurate results. Finally, the proposed methods were successfully applied to the experimental determination of the diffusion coefficient of water (50°C) in the homopolymer of 2‐hydroxyethyl methacrylate (HEMA) and in the copolymer of HEMA with triethylene glycol dimethacrylate (98/2 mol/mol). These polymers were prepared by light curing (λ = 470 nm) at room temperature in presence of camphorquinone and N,N‐dimethylaminoethyl methacrylate as initiator. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Kinetics and thermodynamics of water adsorption onto rice husks ash filled polypropene composites during soaking

The kinetics and thermodynamics of water adsorption onto rice husks ash filled polypropene composites during soaking were studied at different temperatures, quantities and nature of fillers. Raw rice husk, “white” and “black” rice husks ash and Aerosil were used as fillers of polypropene. The increase of fillers contents in the polymer matrix was found to result in non-linear increase of the amount of adsorbed water. The highest adsorption capacity showed the samples filled with raw rice husks, while the lowest—those filled with black rice husks ash. The adsorption kinetics was limited by intra-particle diffusion in plane sheet particles. The values of the diffusion coefficients D, diffusion constants D ^o, activation energy of the diffusion process Е _а, changes of free energy ΔG ^≠, enthalpy ΔH ^≠ and entropy ΔS ^≠ for the formation of the activated complex from the reagent were calculated. A compensation effect between D ^o and Е _а was observed. Based on the Van’t Hoff equation, the values of the changes of standard free energy ΔG ^o, enthalpy ΔH ^o and entropy ΔS ^o of water adsorption were calculated. The sorption process is exothermal in nature and accompanied with decrease of the entropy. The values of the sorption coefficient S and permeability coefficient P were calculated at 25 and 90 °C.