Development of PE/PCL Bilayer Films Modified with Casein and Aluminum Oxide

The studied samples were prepared from polyethylene (PE) polymer which was coated with modified polycaprolactone (PCL) film in order to obtain bilayer films. Thin PCL film was modified with casein/aluminum oxide compound to enhance vapor permeability as well as mechanical and thermal properties of PE/PCL films. Casein/aluminum oxide modifiers were used in order to achieve some functional properties of polymer film that can be used in various applications, e.g., reduction of water vapor permeability (WVTR) and good mechanical and thermal properties. Significant improvement was observed in mechanical properties, especially in tensile strength as well as in water vapor values. Samples prepared with aluminum oxide particles indicated significantly lower values up to 60%, and samples that were prepared with casein and 5% Al₂O₃ showed the lowest WVTR value.     

热处理条件对PVA薄膜阻氢性能的影响

采用XRD测定了PVA薄膜在不同热处理条件下的结晶度,并用自行设计的渗氢系数测量系统研究了在不同热处理条件下的PVA薄膜阻氢性能的变化规律。结果表明,PVA薄膜的热处理温度越高,其结晶度越高,越有利于提高PVA薄膜的阻氢性能,但热处理温度宜选择在180℃以下,以防止PVA薄膜热降解,另一方面,在PVA的玻璃化转变温度以下进行热处理同样能够提高PVA薄膜的阻氢性能,而醇解度较低的PVA薄膜在玻璃化转变温度以下经热处理后的阻氢性能提高的幅度较大。     

Intrinsically microporous polyimides containing spirobisindane and phenazine units: Synthesis,characterization and gas permeation properties

A new diamine containing spirobisindane and phenazine units, namely, 3,3,3′,3′‐tetramethyl‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[cyclopenta[b]phenazine]‐7,7′‐diamine (TTSBIDA) was synthesized starting from commercially available 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobisindane (TTSBI). TTSBI was oxidized to 3,3,3′,3′‐tetramethyl‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[indene]‐5,5′,6,6′‐tetraone (TTSBIQ) which was subsequently condensed with 4‐nitro‐1,2‐phenylenediamine to obtain 3,3,3′,3′‐tetramethyl‐7,7′‐dinitro‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[cyclopenta[b]phenazine] (TTSBIDN). TTSBIDN was converted into TTSBIDA by reduction of the nitro groups using hydrazine hydrate in the presence of Pd/C as the catalyst. A series of new polyimides of intrinsic microporosity (PIM‐PIs) were synthesized by polycondensation of TTSBIDA with commercially available aromatic dianhydrides. PIM‐PIs exhibited amorphous nature, high thermal stability (T₁₀ > 480 °C) and intrinsic microporosity (BET surface area = 59–289 m²/g). The gas permeation characteristics of films of selected PIM‐PIs were evaluated and they exhibited appreciable gas permeability as well as high selectivity. The CO₂ and O₂ permeability of PIM‐PIs were in the range 185.4–39.2 and 30.6–6.2 Barrer, respectively. Notably, polyimide derived from TTSBIDA and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (PIM‐PI‐6FDA) exhibited high CO₂ and O₂ permeability of 185.4 and 30.6 Barrer with CO₂/CH₄ and O₂/N₂ selectivity of 43.1 and 5.1, respectively. The data of PIM‐PI‐6FDA for CO₂/CH₄ and O₂/N₂ gas pairs were located near Robeson upper bound. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 766–775     

Effect of gap and flow orientation on two-phase flow in an oil-wet gap: Relative permeability curves and flow structures

Naturally fractured reservoirs contain about 25–30% of the world supply of oil. In these reservoirs, fractures are the dominant flow path. Therefore, a good understanding of transfer parameters such as relative permeability as well as flow regimes occurring in a fracture plays an important role in developing and improving oil production from such complex systems. However, in contrast with gas–liquid flow in a single fracture, the flow of heavy oil and water has received less attention. In this research, a Hele-Shaw apparatus was built to study the flow of water in presence of heavy oil and display different flow patterns under different flow rates and analyze the effect of fracture orientations on relative permeability curves as well as flow regimes. The phase flow rates versus phase saturation results were converted to experimental relative permeability curves. The results of the experiments demonstrate that, depending on fracture and flow orientation, there could be a significant interference between the phases flowing through the fracture. The results also reveal that both phases can flow in both continuous and discontinuous forms. The relative permeability curves show that the oil–water relative permeability not only depends on fluid saturations and flow patterns but also fracture orientation.     

Determination of fexofenadine in Hank's balanced salt solution by high‐performance liquid chromatography with ultraviolet detection: application to Caco‐2 cell permeability studies

The drug‐transporting proteins can affect the pharmacokinetics and pharmacodymanics of many drugs, resulting in an erratic and unpredictable pharmacological response. The Caco‐2 monolayer is routinely applied to investigate the carrier‐mediated transport of drugs. Therefore, the selection of a marker compound able to characterize the activity of such transporters is crucial. Fexofenadine (FEX), a P‐gp/OATP substrate, can be considered a suitable probe. However, in order to use be used as a marker compound, it is mandatory to develop an analytical method able to quantify this drug during the in vitro permeability assay. An HPLC method with ultraviolet detection was developed; the mobile phase consisted of phosphate buffer (pH 3.2) containing 10 m m of sodium octanosulphonate and acetonitrile (60:40) and the flow rate was set at 1.2 mL/min. Fexofenadine was eluted at 40°C, the retention time was about 4.6 min. The LOD and LOQ values were 1.9 and 6.2 ng/mL, respectively. Verapamil and ketoconazole, the most common P‐gp inhibitors, were eluted as distinct peaks of that corresponding to fexofenadine The method was successfully applied to quantify the amount of FEX transported across the Caco‐2 monolayer and could be an additional tool for those investigating the role of membrane transporters on drug absorption. Copyright © 2014 John Wiley & Sons, Ltd.     

Degradation of a polyester‐urethane coating: Physical properties

In this article we studied the evolution of thermomechanical properties of a polyester‐urethane coating during degradation under different degradation conditions, i.e., aerobic and anaerobic conditions with and without dry/wet cycling during degradation. Dynamic mechanical and thermal analyses show that under aerobic conditions the coatings become stiffer and more brittle in the glassy state. This stiffening is probably due to the increase in the amount of hydrogen bonding and the formation of oxidized groups which increase the polarity of the material and enhance the interactions of the polymer segments. However, oxidation reactions result in a considerable decrease in cross‐link density and stiffness in the rubbery state. Both changes, in the glassy and rubbery states, give rise to development of internal stresses. These stresses increase as the degradation process proceeds. Nevertheless, for samples exposed to anaerobic conditions, the stiffness remains constant in the glassy state and the cross‐link density slightly increases as a result of degradation. This reconfirms the dominance of the effect of oxidation reactions on the mechanical failure of the coatings. Oxygen permeation measurements show a more‐or‐less time‐independent diffusion coefficient and a gradual decrease in solubility of oxygen as a function of exposure time. This results in a slight decrease in oxygen permeation (mainly in the early stage of the degradation) as degradation proceeds. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 659–671     

Implementation of ADER scheme for a bore on an unsaturated permeable slope

The paper details the implementation of the Godunov‐type finite volume Arbitrary high order schemes using Derivatives (ADER) scheme for the case of a large source term in the continuity equation of the nonlinear shallow water equations. The particular application is the movement of a bore on a highly permeable slope. The large source term is caused by the infiltration into the initially unsaturated slope material. Infiltration is modelled as vertical downwards piston‐like flow with Forchheimer quadratic parameterisation of the resistance law. The corresponding ODE is solved using the fourth‐order Runge–Kutta method. The surface and subsurface flow models have been tested by comparison with analytical solutions. Example predictions of surface bore propagation and wetting front propagation are presented for a range of slope permeabilities. The effects of permeability on bore run‐up, water depths and velocities are illustrated. The ADER scheme is capable of handling the source term, including the extreme case when this term dominates the volume balance. Copyright © 2011 John Wiley & Sons, Ltd.     

Cross‐linked poly(aryl ether sulfone) membranes for direct methanol fuel cell applications

Partially sulfonated poly(aryl ether sulfone) (PESS) was synthesized and methacrylated via reaction with glycidyl methacrylate (PESSGMA) and cross‐linked via radical polymerization with styrene and vinyl‐phosphonic acid (VPA). The chemical structures of the synthesized pre‐polymers were characterized via FTIR and ¹H NMR spectroscopic methods and molecular weight was determined via GPC. Membranes of these polymers were prepared via solution casting method. The crosslinking of the PESS polymer reduced IEC, proton conductivity, swelling in water, and methanol permeability of the membranes while increasing the modulus and the glass transition temperature. However, the introduction of the VPA comonomer increased the proton conductivity while maintaining excellent resistance to methanol cross‐over, which was significantly higher as compared with both PESS and the commercial Nafion membranes. Membranes of PESSGMA copolymers incorporating VPA, exhibited proton conductivity values at 60 °C in the range of 16–32 mS cm⁻¹ and methanol permeability values in the range of 6.52 × 10⁻⁹ – 1.92 × 10⁻⁸ cm² s⁻¹. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 558–575