Investigation of charge transport properties in conducting copolymers of aniline with 3‐aminobenzenesulfonic acid for their applications as antistatic encapsulation materials blended with low‐density polyethylene

The electrostatic charge dissipative (ESD) properties of conducting self‐doped and PTSA-doped copolymers of aniline (AA), o‐methoxyaniline (methoxy AA) and o‐ethoxyaniline (ethoxy AA) with 3‐aminobenzenesulfonic acid (3‐ABSA) blended with low‐density polyethylene (LDPE) were investigated in the presence of external dopant p‐toluenesulfonic acid (PTSA). Blending of copolymers with LDPE was carried out in a twin‐screw extruder by melt blending by loading 1.0 and 2.0 wt% of conducting copolymer in the LDPE matrix. The conductivity of the blown polymers blended with LDPE was in the range 10^?12–10^?6 S cm^?1, showing their potential use as antistatic materials for the encapsulation of electronic equipment. The DC conductivity of all self‐doped homopolymers and PTSA‐doped copolymers was measured in the range 100–373 K. The room temperature conductivity (S cm^?1) of self‐doped copolymers was: poly(3‐ABSA‐co‐AA), 7.73 × 10^?4; poly(3‐ABSA‐co‐methoxy AA), 3.06 × 10^?6; poly(3‐ABSA‐co‐ethoxy AA), 2.99 × 10^?7; and of PTSA‐doped copolymers was: poly(3‐ABSA‐co‐AA), 4.34 × 10^?2; poly(3‐ABSA‐co‐methoxy AA), 9.90 × 10^?5; poly(3‐ABSA‐co‐ethoxy AA), 1.10 × 10^?5. The observed conduction mechanism for all the samples could be explained in terms of Mott's variable range hopping model; however, ESD properties are dependent upon the electrical conductivity. The antistatic decay time is least for the PTSA‐doped poly(3‐ABSA‐co‐AA), which has maximum conductivity among all the samples. © 2013 Society of Chemical Industry     

Dynamic adsorption behaviors between Cu2+ ion and water‐insoluble amphoteric starch in aqueous solutions

Dynamic adsorption behavior between Cu²⁺ ion and water‐insoluble amphoteric starch was investigated. The sorption process occurs in two stages: external mass transport occurs in the early stage and intraparticle diffusion occurs in the long‐term stage. The diffusion rate of Cu²⁺ ion in both stages is concentration dependent. In the external mass‐transport process, the diffusion coefficient (D₁) increases with increasing initial concentration in the low‐ (1 × 10^?3‐4 × 10^?3M) and high‐concentration regions (6 × 10^?3‐10 × 10^?3M). The values of adsorption activation energy (k_d1) in the low‐ and high‐concentration regions are 15.46–24.67 and ?1.80 to ?11.57 kJ/mol, respectively. In the intraparticle diffusion process, the diffusion coefficient (D₂) increases with increasing initial concentration in the low‐concentration region (1 × 10^?3‐2 × 10^?3M) and decreases with increasing initial concentration in the high‐concentration region (4 × 10^?3‐10 × 10^?3M). The k_d2 values in the low‐ and high‐concentration regions are 9.96–15.30 and ?15.53 to ?10.71 kJ/mol, respectively. These results indicate that the diffusion process is endothermic in the low‐concentration region and is exothermic in the high‐concentration region for both stages. The external mass‐transport process is more concentration dependent than the intraparticle diffusion process in the high‐concentration region, and the dependence of concentration for both processes is about equal in the low‐concentration region. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2849–2855, 2001     

Characterization of polymeric LB thin films for sensor applications

The Quartz Crystal Microbalance (QCM) system is utilized to investigate the relationship between mass uptake and associated swelling for Langmuir‐Blodgett (LB) organic thin films obtained from pyrene end‐capped polystyrene (PS). The study was carried out using three different molecular weights of polymeric chains. The changes in resonance frequency associated with mass changes can be attributed to the swelling behavior of polymeric thin films during vapor absorption. This swelling is due to the capturing of organic vapor molecules in the sensor environment. To quantify real‐time QCM data for swelling, early‐time Fick's law of diffusion was adopted to fit the results, and a good linear relationship was observed between the mass uptake and square root of the swelling time. The diffusion coefficients for swelling were thus obtained from the slopes of the fitting curves and was found to be correlation with the amount of organic vapor content in the cell. It was also observed that diffusion of the organic vapor into higher molecular weight polystyrene thin films are much faster than low molecular weight ones in sensor applications. Diffusion coefficients were found to be 0.2–3.0 × 10^?16, 5.0–13 × 10^?16, and 1.0–1.6 × 10^?15 cm²/s for PS1, PS2, and PS3 LB thin films, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Electrical conduction mechanism in plasma polymerized 2‐(diethylamino)ethyl methacrylate thin films

Thin films of different thicknesses were prepared through glow discharge of 2‐(diethylamino)ethyl methacrylate (DEAEMA) using a capacitively coupled reactor. Current density–voltage (J–V) characteristics for plasma polymerized (PP) DEAEMA thin films of thicknesses 100, 200, 250, and 300 nm in aluminum/PPDEAEMA/aluminum sandwich configuration were studied over the temperature range from 298 to 423 K. J–V curves reveal that in the low‐voltage region, the conduction current obeys Ohm's law while in the high‐voltage region the behavior attributed to be space charge‐limited conduction in PPDEAEMA thin films. The carrier mobility was calculated to be about 6.80 × 10^?19 to 2.38 × 10^?18 m^?2 V^?1s^?1 for various thicknesses. The free carrier density was found to be about 1.78 × 10²³ to 2.04 × 10²³ m^?3, and the trap density was found to be about 6.93 × 10²³ to 15.9 × 10²³ m^?3 for different thicknesses. The activation energies were estimated to be about 0.005–0.016 eV for 2 and 30 V of PPDEAEMA thin films of different thicknesses. The low‐activation energies indicate that the thermally activated hopping conduction is operative in PPDEAEMA thin films. POLYM. ENG. SCI., 55:2729–2734, 2015. © 2015 Society of Plastics Engineers     

Electrochemical method for quantitative determination of trace amounts of disperse dye in wastewater

The electrochemical behaviour of Disperse Red 13 dye at a glassy carbon electrode was investigated in both organic and aqueous organic mixtures. Best results were obtained in N,N‐dimethylformamide/Britton–Robinson buffer (1:1, v/v), which displays a well‐defined peak at ‐0.40 V (vs Ag/AgCl) owing to reduction of the protonated nitro group. This method can be successfully applied to the electroanalytical determination of Disperse Red 13 in a very simple and inexpensive way. All the differential pulse voltammetry parameters were optimised by using a glassy carbon electrode modified with poly(glutamic acid) films. The targeted analytical method presented a linear response from Disperse Red 13 concentrations between 2.5 × 10^?7 and 3 × 10^?6 mol l^?1 (r = 0.997), with a detection limit of 1.5 × 10^?8 mol l^?1 and recoveries of 89.7–95.10% in water samples. Disperse Red 13 was successfully determined in textile industry wastewater by means of the proposed method after pre‐extraction in a solid‐phase extraction cartridge.     

Methylene blue adsorption from aqueous solutions to flexible poly(vinyl chloride) silica composites

Methylene blue (MB) adsorption studies were performed with poly(vinyl chloride)‐(dioctyl phthalate)‐silica composites, which were obtained by using plastisol‐plastigel technology. The films were flexible, having elastic modulus of 1.0–1.5 GPa. Diminishing MB concentration in the aqueous phase was followed as the adsorption process advanced by using visible spectroscopy. Contributions of the individual components of the composites to adsorption were also investigated. Although the MB adsorption capacity was extensively high for silica, it was moderate for the composite, most likely owing to the occlusion of pores of silica by plasticizer to some extent. The improvement of MB adsorption capacity of the composites as the silica ratio increased was explicitly deduced from the optical microscopy photographs. The diffusion coefficients of MB through the composites were 5 × 10^?13, 6 × 10^?13, and 3 × 10^?13 m² s^?1 with regression coefficients of 0.73, 0.89, and 0.88 for 0, 2, and 16% silica‐containing composites, respectively. Because of the slow diffusion of MB in poly(vinyl chloride)‐silica composites, using them as dynamic column adsorbent was not practical. However, these versatile plastics can be used as plastic labels, colored clothing, leather substitutes, antimicrobial medical devices, and laser printable surfaces. J. VINYL ADDIT. TECHNOL., 21:42–50, 2015. © 2014 Society of Plastics Engineers     

Effect of polymer–clay interaction on solvent transport behavior of fluoroelastomer–clay nanocomposites and prediction of aspect ratio of nanoclay

Diffusion and sorption of methyl ethyl ketone and tetrahydrofuran through fluoroelastomer‐clay nanocomposites were investigated in the temperature range of 30–60°C by swelling experiments. Slightly non‐Fickian transport behavior was found for these nanocomposites, having variation of type of nanoclay and loading. Different transport parameters depend on the size and shape of the penetrant molecules. The results were used to study the effect of nanoclay on the solvent transport‐properties of nanocomposites and their interactions with solvents. The diffusion coefficient of methyl ethyl ketone at 30°C for neat rubber was 1.43 × 10^?8 cm² s^?1, while those of the unmodified and the modified clay filled samples at 4 phr loading were 0.24 × 10^?8 and 0.50 × 10^?8 cm² s^?1, respectively. At 8 and 16 phr loading of the unmodified clay, it was found to be 0.44 × 10^?8 and 0.64 × 10^?8 cm² s^?1, respectively. The samples were also reswelled after deswelling. Surprisingly, transport behavior became Fickian on reswelling. Interestingly, ratio of diffusion coefficients of the filled system to the neat system was found to be almost same for the first time swelling and reswelling experiments. The results showed that better polymer‐clay interaction in the case of the unmodified‐clay filled nanocomposites is responsible for enhanced solvent‐resistance property. From the permeation data, for the first time, aspect ratio of nanoclays in different composites was calculated and found to have good correlation with the morphology data obtained from transmission electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Migration of phthalate and non‐phthalate plasticizers out of plasticized PVC films into air

The aim of the present work is to provide information about the migration of phthalate and non‐phthalate plasticizers generally used in flexible polyvinyl chloride (PVC) applications. Plastisols (pastes) were prepared by mixing PVC, plasticizer, and thermal stabilizer. The plasticized PVC (p‐PVC) films are obtained by gelation at 160°C for 15 min. The p‐PVC films were heat treated at 50, 85, 100, 130, and 160°C up to 420 min to follow the mass loss to find out diffusivity of plasticizer out of films into air and to determine related activation energies. The films having di‐octyl terephthalate (DOTP) and di‐isononyl 1,2‐cyclohexanedicarboxylic acid (DINCH) exhibited the lowest mass loss in general, among the phthalate and non‐phthalate plasticizer having p‐PVC films, respectively, as confirmed by FTIR investigation. The same tendency was observed for diffusion coefficients and for the activation energies of migration. The diffusion coefficients were found to be around 3.5 × 10^?18–2.1 × 10^?17 m²/sec for the studied plasticizers in PVC at 50°C and around 4.0 × 10^?15–9.9 × 10^?14 m²/sec at 160°C. The activation energies for 85–160°C interval were determined to be between 70 and 153 kJ/mol (0.72–1.58 eV) for the plasticizers used herein those could be treated as a homologous series as deduced from the related compensation factors. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Study on physiochemical structure and in vitro release behaviors of doxycycline‐loaded PCL microspheres

This study aimed to develop drug delivery system of doxycycline‐loaded polycaprolactone (PCL) microspheres. The investigated microsphere formulation can be considered for local application in bone infections and degenerative joint diseases, which generally require long‐term treatments via systemic drugs. PCL‐14 kDa and 65 kDa were used in microsphere preparation. Before release, the microspheres were characterized by scanning electron microscopy, differential scanning calorimetry, and X‐ray photoelectron spectroscopy. The mean particle size of microspheres was in the range of 74–122 µm and their drug loadings ranged between 10 and 30%. In vitro release profiles were described using the Higuchi and the Korsmeyer–Peppas equations. Diffusion model was applied to experimental data for estimating diffusion coefficients of microspheres; calculated as between 4.5 × 10^?10 and 9.5 × 10^?10 cm²/s. Although long‐term release from microspheres of PCL‐14 kDa obeyed diffusion model, PCL‐65 kDa microspheres showed this tendency only for some period. Modeling studies showed that the drug release mechanism was mainly dependent on loading and molecular weight differences. Release behavior of PCL‐65 kDa microspheres, however, might be better represented by derivation of a different equation to model for the total release period. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41768     

Transport and dielectric properties of poly(ethylene terephthalate) as determined via electrochemical techniques

The electrochemical impedance spectroscopy (EIS) technique was used to evaluate the water transport (diffusion and equilibrium water uptake) and the dielectric properties of free-standing poly(ethylene terephthalate) (PET) membranes at 40°C. Permeability and diffusion coefficients were also obtained using the Payne cup method and the MacBain quartz spring balance to assess the reliability of the EIS method when compared to other techniques. In addition, an electromigration (dc) technique was used to estimate the NaCl diffusion coefficient across PET films. Results obtained indicate that PET is highly permeable to water and much less permeable to salt. The water diffusion coefficient, D, varies from 2.11× 10^?9 to 9.97× 10^?9 cm²s^?1 for thicknesses between 22 and 205μm, whereas the equilibrium water uptake, W, varies from 0.54 to 0.95 wt % for the same given range of thicknesses. The average calculated dielectric constant of the free-standing PET films is 3.6. An estimate of the NaCl diffusion coefficient, D_s, is 9.34× 10^?14 cm²s^?1. Transport properties results obtained via the electrochemical technique are in reasonable agreement with those obtained with the classical gravimetric method. © 1993 John Wiley & Sons, Inc.     

Water sorption behaviors of the BPDA‐based polyimide films depending upon the structural isomers of diamine

For the biphenyltetracarboxylic dianhydride (BPDA)‐based polyimide thin films, the water sorption behaviors were gravimetrically investigated by using a thin film diffusion analyzer. The water sorption behaviors of the polyimide thin films are quite different and strongly dependent upon the sort of polyimide. The diffusion coefficients of the polyimide thin films vary in the range of 1.6 × 10⁻¹⁰ to 12.4 × 10⁻¹⁰cm²/s and the water uptakes vary from 1.52 to 5.25 wt %. Both the diffusion coefficient and water uptake of the polyimide thin films are in the increasing order: BPDA‐pPDA < BPDA‐p,p′ODA < BPDA‐p,m′ODA < BPDA‐mPDA ∼ BPDA‐p,p′DDS < BPDA‐m,m′DDS. Specifically, the polyimide films with para‐oriented linkages in backbone structure showed relatively lower diffusion coefficient and water uptake than the corresponding polyimide films with meta‐oriented linkages because of the well‐developed crystalline structure and good intermolecular chain ordering. In addition, the polyimide thin films having higher chain order showed relatively lower diffusion coefficient and water uptake. The crystallinity and intermolecular chain ordering in the morphological structure are critical parameters in controlling the water sorption behaviors of the polyimide thin films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2121–2127, 2001     

Effect of hydrophobic hexafluoroisopropylidene group on the water sorption behaviors of rigid poly(p‐phenylene pyromellitimide) polyimide thin films

We prepared poly(p‐phenylene pyromellitimide) (PMDA–PDA), poly(p‐phenylene 4,4′‐hexafluoroisopropylidene diphthalimide), and their copolyimides with various compositions to explore the relationship between the water sorption and structure. The water sorption behaviors were gravimetrically investigated as a function of composition and temperature and interpreted with a Fickian diffusion model in films. Overall, the water sorption behaviors were strongly dependent on the changes in morphological structure, which originated from the variations in composition. When the content of the bulky hexafluoroisopropylidene group (6FDA) was increased, the water uptake decreased from 5.80 to 3.18 wt %, whereas the diffusion coefficient increased from 3.6 × 10^?10 to 11.3 × 10^?10 cm²/s. The relatively high water uptake in the PMDA–PDA polyimide film was successfully healed by the incorporation of 6FDA, which may have resulted from the increases in the intermolecular packing order and hydrophobicity. The degree of orientation and crystallinity, which are in‐plane characteristics, were directly correlated to the diffusion coefficient and activation energy in the polyimide film. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3442–3446, 2003     

Diffusivities of dichloromethane in poly(lactide‐co‐glycolide)

Diffusion of dichloromethane in poly(lactide‐co‐glycolide) (PLGA), the rate‐limiting step in the later stages of drying of microparticles formed in common encapsulation processes, was studied by the step‐change sorption technique in a dynamic vapor sorption apparatus. Methods were developed to create films of polymer with the appropriate thicknesses for accurate diffusion determination over a wide range of solvent composition. Mutual diffusivities were measured at 5, 25, and 35°C from 10 to 70 wt % solvent. Values range from 2 × 10^?10 m²/s at high solvent compositions to as low as 1 × 10^?13 m²/s at solvent compositions just above the glass transition of the mixture. Equilibrium sorption isotherms were measured in the same apparatus and agreed favorably with Flory‐Huggins theory using a value of χ = 0.31. The glass transition temperatures of the system were measured over the range of 0–11 wt % solvent content by modulated differential scanning calorimetry. The composition dependence was fit to the Fox equation, which estimated values of the pure polymer and the solvent T_g to be 39.3 and ?131°C, respectively. These values, along with the diffusivity data, were used to deduce the free‐volume parameters specific to PLGA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Oxo‐biodegradability of high‐density polyethylene films containing limited amount of isotactic polypropylene

Limited amount of isotactic polypropylene (iPP) is added to high‐density polyethylene (HDPE) containing 1% w/w an oxo‐biodegradable additive and extruded and converted to films. The films are put under UV irradiation for different periods of time. Irradiation of the films for 6 weeks imposes remarkable effects on viscosity average molecular weight (M_v) and carbonyl index (CI) of them. M_v decreases from 3.4 × 10⁵ to 4.7 × 10⁴ g mol^?1 for neat HDPE films; from 3.1 × 10⁵ to 3.3 × 10⁴ g mol^?1 for the films containing oxo compound, and from 1.5 × 10⁵ to 2.6 × 10⁴ g mol^?1 for the films containing oxo compound and 1% w/w iPP. Carbonyl index of the neat HDPE films increases from 4 to 8.7 while for the sample containing only the oxo compound it increases from 4.5 to 7.3 and for the sample containing both oxo compound and iPP it decreases from 12.0 to 8.8. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicate more cracks and uniform degradation in the samples containing iPP and oxo compound. Thermogravimetric analysis (TGA/DTG) of the samples shows that the samples containing iPP and oxo compound have lower decomposition temperature after UV irradiation. Finally, it can be said that the presence of iPP in HDPE matrix containing oxo compound can improve HDPE oxo‐biodegradablity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45843.     

Permeability of small molecules through vapor deposited polymer membranes

Free‐standing, thin films of poly(2‐hydroxyethyl methacrylate), p(HEMA), membranes deposited by initiated chemical vapor deposition (iCVD) technique are presented. Systematic studies of permeation of model dye molecules through these free‐standing thin films are performed and effects of process parameters on the permeability and selectivity of the membranes synthesized using an all‐dry process are demonstrated for the first time. Permeation studies of model dye molecules show that the diffusion of large dye molecules through the membrane is faster than the smaller dye molecules, due to loss of conformation entropy. Mesh sizes of the membranes are controlled by tuning the crosslink ratio of the polymer and diffusion coefficients of alizarin yellow model dye molecules are obtained as 0.44 × 10^?7 and 1.71 × 10^?7 cm²/s for high and low crosslinked membranes, respectively. Selectivity of the membranes is also demonstrated by the permeation studies of dyes with similar sizes but different polarities and the permeability coefficient of the hydrophilic dye is observed to be 30 times larger than that of the hydrophobic dye of similar size. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42453.     

Studies on Micellar Behavior of PEO‐PBO or PEO‐PBO‐PEO Copolymers,or Surface Active Amphiphilic Ionic Liquids in Aqueous Media and Exploration of the Micellar Solutions for Solubilization of Dexamethasone and its Delayed Release

The aggregation behavior of a di‐ and tri‐block copolymers of type PEO‐PBO, PEO‐PBO‐PEO, surface‐active ionic liquid (SAIL) of type 4‐dodecyl‐4‐methylmorpholinium chloride [C₁₂mmor][Cl], and 1‐dodecyl‐1‐methylpyrrolidinium chloride [C₁₂mpyrr][Cl]) in water as well as in 10 mM of a poorly water soluble dexamethasone (dex) aqueous solution was studied by determining the critical micelle concentrations using drug solubilization, surface tension, and isothermal titration calorimetry (ITC) methods. ITC measurements were also made on solutions prepared by mixing the micellar aqueous solutions of copolymers and simple aqueous solutions of SAIL across the mole fractions at three different temperatures (298.15, 308.15, and 318.15 K). The thermodynamic parameters, namely Gibbs free energy (ΔG_m), enthalpy (ΔH_m), and entropy (ΔS_m), of micellization were calculated, and it was observed that the negative ΔG_m and positive ΔS_m for the mixture solutions increase with the increase in mole fraction of SAIL. Otherwise, the micellization is reported to be a spontaneous and highly entropy‐driven process. The dex‐solubilized micellar solutions were mixed with agar to obtain standing gels. The gel samples were dry‐cast into thin films, and the release of dex from films by simple dilution was monitored by UV measurements. The drug release data was fitted to several mechanistic models, and it was inferred that the release mechanism for dex from thin films is non‐Fickian for mixtures and Fickian in copolymer or SAIL micellar aqueous solutions. The transport of dex is diffusion‐controlled with diffusivities of 5.8–12 × 10^?11 m² s^?1 for copolymer micelles, 5–11 × 10^?11 m² s^?1 for micelles of SAIL, and 3–14 × 10^?11 m² s^?1 for the mixed micelles of copolymer and SAIL in aqueous media.     

The preparation,characterization, and cure reactions of new bisbenzocyclobutene‐terminated aromatic imides

Several new bisbenzocyclobutene‐terminated aromatic imides, 2,2′‐bis(N‐4‐benzocyclobutenyl) phthalimide, 2,2′‐bis[4‐(N‐4‐benzocyclobutenylphthalimide)]‐ether, 2,2′‐bis[4‐(N‐4‐benzocyclobutenylphthalimide)]‐ketone, and 2,2′‐bis[4‐(N‐4‐benzo cyclobutenylphthalimid‐4‐oxy) phenyl]‐propane, have been synthesized in high yields and characterized by FTIR, MS, EA, and ¹H NMR spectroscopy. The polymers cured from benzocyclobutene‐terminated imides have high glass transition temperature and good thermal stabilities. The cure reaction of an imide was studied by FTIR‐ATR (attenuated total reflection) and DSC techniques. Apparent kinetic parameters of the cure reaction are obtained. The apparent cure reaction order, activation energy, and pre‐exponential factor determined by isothermal DSC method are 1, 143.4 kJ/mol, and 3.88× 10¹³ min^?1, and by nonisothermal DSC methods 1, 139.4 kJ/mol, and 2.27× 10¹³ min^?1, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1705–1719, 2006     

Bending-beam measurement of solvent diffusions in polyimides: Theoretical and experimental

A general formula correlating the bending curvature variation ratio of a layered structure caused by solvent-induced swelling in its polymer overcoat with diffusion time under case II diffusion has been presented. In the event of case II diffusion, the diffusion front velocity, v, can be calculated by using this formula and measured by a bending-beam apparatus. At room temperature, the diffusion of n-methyl-pyrrolidone (NMP) solvent in the film of pyromellitic phenylene diamine (PMDA-PDA) is case II. While in PMDA-B (-benzidine) and benzophenone tetracarboxylic dianhydride (BPDA-PDA), no diffusion progress can be observed. But, the diffusion in 6F-dianhydride- (6FDA-PDA) is case I with D = 0.85 × 10^?9 cm²/s. It becomes anomalous when mixing with 25% PMDA-B, but becomes case II diffusion with more PMDA-B. The preabsorbed moisture in the films does not affect the v value. In PMDA-PDA, v = 7.3 × 10^?8 cm/s. In the 25/75 and 50/50 6FDA-PDA/PMDA-B blends, v = 6.3 and 11.3 × 10^?8 cm/s.     

Adsorption of butanol from aqueous solution onto a new type of macroporous adsorption resin: Studies of adsorption isotherms and kinetics simulation

BACKGROUND: Owing to the rapid depletion of petroleum fuel, the production of bio‐butanol has attracted much attention. However, low butanol productivity severely limits its potential industrial application. It is important to establish an approach for recovering low‐concentration butanol from fermentation broth. Experiments were conducted using batch adsorption mode under different conditions of initial butanol concentration and temperature. Batch adsorption data were fitted to Langmuir and Freundlich isotherms and the macropore diffusion, pseudo‐first‐ and second‐order models for kinetic study. RESULTS: The maximum adsorption capacity of butanol onto KA‐I resin increase with increasing temperature, ranged from 139.836 to 304.397 mg g^?1. The equilibrium adsorption data were well fitted by the Langmuir isotherm. The adsorption kinetics was more accurately represented by the macropore diffusion model, which also clearly predicted the intraparticle distribution of the concentration. The effective pore diffusivity (D_p) was dependent upon temperature, but independent of initial butanol concentration, and was 0.251 × 10^?10, 0.73 × 10^?10, 1.32 × 10^?10 and 4.31 × 10^?10 m² s^?1 at 283.13, 293.13, 303.13 and 310.13 K, respectively. CONCLUSION: This work demonstrates that KA‐I resin is an efficient adsorbent for the removal of butanol from aqueous solutions and available for practical applications for future in situ product recovery of butanol from ABE fermentation broth. Copyright © 2012 Society of Chemical Industry     

Electroanalytical studies on electrically conducting polyaniline:polyethyleneterephthalate composite films

Polyaniline (PANI):polyethyleneterephthalate (PET) composite was prepared by chemical polymerization of aniline diffused in the PET matrix. Thus prepared composite films were characterized by fourier‐transform infrared spectroscopy and scanning electron microscopy and their electrical properties and the thermo‐oxidative stability was studied by thermogravimetry and differential thermal analysis. The stability in terms of DC electrical conductivity retention was studied in an oxidative environment by two slightly different techniques viz. isothermal and cyclic techniques. DC electrical conductivity of composite films was found to be stable up to 90°C for most of the composites under ambient conditions. The composite films were employed as cathode material in secondary cells containing 1M ZnCl₂ solution. The studies were carried out on the charge/discharge cycles under a constant current load 140 mA. The composite films showed similar behavior in electrolyte solution and cell response is reversible. To determine the diffusion coefficient for the chloride ions diffusion into the composite films electrochemically, galvanostatic pulse method was used. The diffusion coefficient was estimated to be ～ 3.28 × 10^?12 cm² s^?1. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010