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1.
Chitosan beads were cross‐linked with glutaraldehyde (GA) and epichlorohydrin (EP), respectively, at variable composition. The general features of the adsorptive and textural properties of the bead systems were characterized using p‐nitrophenolate (PNP) at pH 8.5. As well, a systematic adsorption study of phosphate dianion (phosphate ( ) species was carried out in aqueous solution at pH 8.5 and 295 K. The Sips isotherm model yielded adsorption parameters for the chitosan bead systems: (i) monolayer adsorption capacity (Qm) for PNP ranged from 0.30 to 0.52 mmol g?1 and (ii) Qm values for the bead systems with ranged from 22.4–52.1 mg g?1 for these conditions. GA cross‐linked beads reveal greater Qm values for PNP while EP cross‐linked beads showed greater Qm values for , in accordance with the surface chemistry and the materials design described herein. The EP cross‐linked beads show favorable adsorption–desorption properties and represents a promising tunable adsorbent system for the effective removal of phosphate dianion species in aqueous solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42949.  相似文献   

2.
The effects of polyethylene oxide (PEO) molecular weight (Mv), and volume fraction ( ) on the morphology of electrospun sulfur free softwood lignin nanofibers were investigated. Small amounts of PEO were used during preparations of the solutions to aid the electrospinning process. It was found that tripling the PEO volume fraction resulted in a transition from semi‐dilute un‐entangled to semi‐dilute entangled solutions. Conversely, the solution remained in the semi‐dilute un‐entangled regime as the molecular weight was increased by five times. The effects of molecular weight and volume fraction of PEO both on entanglement density and fiber morphology were unified by scaling PEO viscosities as a function of . We investigated and discussed conditions that would produce smooth fibers and conditions that would produce fibers with beads. In the case of beads‐on‐a‐string formation, bead widths remained constant regardless of the molecular weight and concentration of PEO, but the bead length changed. Additionally, we observed a decrease in the diameter of the fibers and the dimension of beads (length and width of beads) with an increase in the electric field used for electrospinning. The aspect ratio of beads increased with increases to both the electric field and the PEO molecular weight or concentration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44172.  相似文献   

3.
The preparation of nonwoven mats of electrospun poly(lactic acid)/polyaniline (PANI) blend nanofibers faces some critical challenges that will be addressed in the present work. The challenges are in achieving high and adjustable content of PANI while keeping the spinnable solution nonagglomerated with no need to further filtration that might lead to wrong estimation of PANI content in the mat. We report an unprecedented content of 40% wt of PANI that is achieved using a new two‐step procedure. It is based on: (1) the preparation of the spinnable solution from a friable nonagglomerated and readily dispersible PANI: ‐TSA powder and (2) the use of an optimized mixture of ‐cresol/dichloromethane. The obtained nanofiber mats are characterized by FTIR and UV–vis spectroscopy. The morphology and the thermal stability of the nanofibers are investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The amorphous structure of the nanofibers is verified using XRD measurements. The DC‐conductivity of these blend nanofibers is found to be far larger than the published DC‐conductivity values for blend nanofibers of PANI with PLLA or with other polymers. This is attributed to the high content of PANI in the blend and to the role played by ‐cresol as a secondary dopant. The investigation of the aging effect on the DC‐conductivity reveals an exponential decrease with a characteristic time of weeks. The electrical impedance spectroscopy (EIS) shows a pure ohmic behavior of the blend mat. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43687.  相似文献   

4.
In this study, a novel and useful approach to fabricate @PVP‐CTAB@ (TPS) nanohybrid as an effective light stabilizer agent has been reported. Also, the indirect role of the Polyvinylpyrrolidone and cetyltrimethylammonium bromide on UV (ultraviolet) protection properties of nanohybrid particles was investigated. In addition, comparative studies were carried out to evaluate the photocatalytic and UV protection properties of @ (TS), commercial (US3490), synthesized nanparticles, and TPS nanoparticles. Furthermore, the UV protection property of 2‐(2H‐benzotriazol‐2‐yl)?4, 6‐bis (1‐methyl‐1‐phenylethyl) phenol, as an organic anti UV, was also compared with TPS nanoparticles. The as prepared nanohybrid was characterized by Fourier transform infrared spectroscopy, zeta potential, field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and UV‐Vis spectroscopy. FESEM and TEM micrographs show monodispersity and nano‐metric size of TPS. Rhodamine B degradation study clearly shows that TPS present the lowest photocatalytic property. Also, UV‐Vis spectroscopy results show that the TPS nanoparticles illustrate higher UV blocking ability comparing to other presented anti UV materials. TPS with convenient and useful synthesis method, high UV blocking ability, and little effect on polymer matrix can be introduced as a novel UV‐blocking agent in polyurethane matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44148.  相似文献   

5.
We prepared pressure‐sensitive adhesive (PSA)‐containing cross‐linked siloxane powders (CS) as a reservoir for a transdermal drug delivery system (TDDS) and evaluated their sustained drug‐release properties. PSA, as a patch‐type adhesive, was synthesized by a hydrosilylation reaction of vinyl‐terminated polysiloxanes with hydrogen‐terminated polydimethylsiloxanes. CS was also prepared via a hydrosilylation process with vinyl‐terminated polydimethylsiloxane, 1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinyltetracyclosiloxane ( ), hydrogen‐terminated polydimethylsiloxane, and dimethylhydrogenmethyl oligomeric siloxane copolymer. The results of release performances using ascorbic acid as a model drug showed a cumulative linear slope over a week, indicating a constant release performance. Our data suggest that this siloxane TDDS could be useful for constant drug release over a long period. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42154.  相似文献   

6.
Electrospun poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) membrane was prepared from a solution of 16 wt % of PVdF‐HFP containing acetone/N,N‐dimethyl acetamide (7:3 wt %). The prepared electrospun PVdF‐HFP membrane (esPM) was then soaked in ionic liquid electrolyte containing 0.5M LiI, 0.05M I2 , and 0.5M 4‐tert butylpyridine, 0.5M 1‐butyl‐3‐methylimidazolium iodide (BMImI) in acetonitrile to get electrospun PVdF‐HFP membrane electrolyte (esPME). The effect of various concentrations of BMImI containing esPME on ionic conductivity was studied by AC‐impedance measurements and the diffusion co‐efficients was determined by linear sweep voltammetry. The photovoltaic performance of a DSSC fabricated using 0.5M BMImI containing electrospun PVdF‐HFP membrane electrolyte (0.5M BMImI‐esPME) has power conversion efficiency (PCE) of 6.42%. But the stability of the DSSC fabricated using 0.5M BMImI‐esPME was considerably superior to that fabricated using 0.5M BMImI containing liquid electrolyte (0.5M BMImI‐LE). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42032.  相似文献   

7.
Borax (Na2B4O7, 10.5% Boron) loaded CMC‐g‐cl‐poly(AAm) hydrogel composites were prepared by in situ grafting of acrylamide on to sodium carboxymethyl cellulose in the presence of borax by free radical polymerization technique to develop slow boron (B) delivery device. The composition, morphology, and mechanical properties of synthesized composites were studied by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, texture analyser, and dynamic shear rheometer. Characterization revealed formation of borate ion ( ) from borax during polymerization reaction leading to extensive crosslinking of cellulosic chains and generation of mechanically strong composite hydrogels. Dynamic release of from the synthesized composites hydrogels followed Fickian diffusion mechanism and composites with high mechanical strength resulted in slow release of B. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43969.  相似文献   

8.
A novel adsorbent for Hg(II), mercapto‐functionalized alkali lignin (AL‐SH) was synthesized by Friedel–Crafts alkylation reaction and nucleophilic substitution reactions. The adsorbent was characterized by the techniques of Fourier transform‐infrared spectroscopy (FT‐IR), elementary analysis and thermogravimetric analysis, and N2 adsorption techniques. The effect of various parameters on Hg(II) adsorption process such as initial pH, contact time, ionic strength, initial Hg(II) concentration, temperature, and adsorbent dosage were investigated in detail through batch static experiments. The results indicated that the adsorption process of Hg(II) on AL‐SH was mainly dependent on the pH and the optimal pH value was at pH ranging from 4.0 to 6.0. The adsorption process was found to follow pseudosecond‐order kinetics and the main process was chemical adsorption, which equilibrated at 8 h. The adsorption isotherm was better described by Langmuir and Temkin isotherm equations compared to Freundlich isotherm equation and the maximum adsorption capacity obtained was 101.2 mg g?1 (pH = 4.0, 20°C, initial Hg(II) concentration was 200 mg L?1). The thermodynamic parameters of and were positive while was negative, revealed that the adsorption of Hg(II) onto AL‐SH was a spontaneous and endothermic process with increased entropy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40749.  相似文献   

9.
This article presents an experimental study on the shape memory behavior of blends of thermoplastic polyurethane (TPU) and biodegradable polylactic acid (PLA) at the PLA/TPU weight ratios of 70/30 (PT7030) and 50/50 (PT5050). The manufactured springs were studied comprehensively based on their morphological and thermal properties. Scanning electron microscopy micrographs were captured, which verified that TPU was compatible with PLA. The wide‐angle X‐ray diffraction suggested that the crystallinity of PLA was enhanced in the presence of TPU. In order to determine the shape recovery properties [shape recovery ratio (Rr), shape fixing ratio (Rf), and shape recovery force (Fr)], the samples programmed at three different temperatures (Tp) of 70, 80, and 90 ° and at various recovery temperatures (Tr) over 40 to 90 ° , were studied. In general, the spring made with PT7030 showed higher Rr, Rf, and Fr values. The highest Rr (99%) was obtained at programmed temperature (Tp) of 70 ° and recovery temperature (Tr) of 90 ° . However, the Rr value for this spring programmed at 70 ° and recovered near body temperature was 50% with Fr of 1.4 N. Furthermore, the highest Fr (15.6 N) was observed in the spring made of PT7030 programmed at 80 ° and recovered at Tr of 78 ° . © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45115.  相似文献   

10.
In this study, we focused on the synthesis, characterization, and adsorption capacity testing of aminated glycidyl methacrylate grafted rice husk (RH‐g‐GMA–Am). Our goal was to obtain a high‐performance surface for the adsorption of various anions. Glycidyl methacrylate grafted rice husk (RH‐g‐GMA) was prepared by the graft copolymerization of glycidyl methacrylate with rice husk; the product was further subjected to an amination reaction. The surface properties, sorption characteristic functional groups, isotherm and kinetic studies, pore diffusion models, and effects of the temperature and pH on the material properties were studied under batch conditions. The IR spectroscopy results show additional surface functional groups for RH‐g‐GMA–Am. The adsorptions of and on RH‐g‐GMA–Am were found to follow pseudo‐second‐order kinetics; this indicated a possible dominant role played by chemisorption. The rate‐limiting step for mass transfer was found to be boundary layer diffusion. Furthermore, the sorption isotherms for and fit the Langmuir model. The amination of RH‐g‐GMA drastically increased the removal efficiency from 3 to 82% and from 6 to 93% for and , respectively. Moreover, RH‐g‐GMA–Am exhibited a better removal efficiency in the pH range of 4–6.5. Regeneration studies revealed that the surface of RH‐g‐GMA–Am could be regenerated repetitively by simple acid washing with an insignificant decrease in the active surface for consecutive adsorptions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43002.  相似文献   

11.
The profiles of PLA/PVA filament parameters (e.g., temperature, velocity, tensile stress, and apparent elongational viscosity) along the spinline in the low‐speed melt spinning process under various spinning conditions were investigated. Owing to the combination of the filament velocity and filament temperature measurements using laser doppler velocimetry (LDV) and infrared thermography, respectively, the fiber formation zone was determined. The length of the fiber formation zone obtained from filament velocity profiles is always shorter than that obtained from the filament temperature profiles ( . Obviously, this unexpected phenomenon occurs for low spinning speeds due to the axial heat conduction effect of the filament along the spinline and the nonuniform radial temperature distribution through the cross‐sectional thick filament. Another remarkable finding is related to the Nusselt number which has been found as nearly constant along the spinline in the low‐speed melt spinning process. Thus, mathematical simulations of the filament temperature profiles will be simplified drastically. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44258.  相似文献   

12.
The present work reports the novel phenomenon of spontaneous formation of gold microplates. The effect is observed as a consequence of , , , and sorption on the Dowex M4195 resin. Therefore an attempt to explain the phenomenon mechanism is made. The research is covering sorption, kinetic and thermodynamic studies. The shapes of formed gold single plates are determined. The uptakes of Au(III), Pt(IV), Pd(II), and Re(VII) tests have been conducted using a batch method from single‐component metals solutions in 0.1M HCl. The sorption‐reduction phenomenon has been assessed by executed SEM, FTIR, XRD, and XPS studies. The greatest sorption capacity, combined with reduction‐coupled removal phenomenon, has been achieved for gold (5.5 mmol Au·g?1 at 9°C). Executed SEM and XRD analyzes prove formation of gold single crystals during present process, furthermore reduction of rhenium is indicated by XPS analysis. Based on the obtained FTIR and Raman's spectra, the reduction phenomenon is probably followed by resins’ functional groups oxidation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42425.  相似文献   

13.
Low density polyethylene films used for greenhouse covering were naturally weathered for 6 months in sub‐Saharan region (Algeria). The microstructural and morphological changes have been checked by infrared spectroscopy. The changes of the mechanical properties have been followed by tensile and creep‐recovery tests. The measurements were carried out in the two main directions of the film plane. Besides oxidation, chain scission and crosslinking are competing during all the ageing protocol, affecting thereby, the mechanical properties as well as the viscoelastic behavior revealed by creep‐recovery curves. The anisotropic character of the film is preserved during ageing. The improvement of the creep resistance via crosslinking in both directions, affects the different deformations. The short chain segments coming from chain scissions increase the crystallinity ratio (via a chemo‐crystallization process) lowering by consequence each of the minimum strain rate ( ), the instantaneous ( ), and delayed recoveries ( ) as well. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44209.  相似文献   

14.
The polypyrrole and polyaniline copolymer coating (PPy‐PAni) and PPy‐PAni doped with sodium molybdate copolymer coating ( ) were synthesized on stainless steel by cyclic voltammetry. The effect of molybdate on the passivation of stainless steel was investigated by linear sweep voltammetry in 0.2 mol L?1 of oxalic acid. The corrosion prevention performances of these copolymer coatings for stainless steel were investigated by linear sweep voltammetry, electrochemical impedance spectroscopy in 1 mol L?1 of sulfuric acid, and potentiodynamic polarization in 0.1 mol L?1 of hydrochloric acid. Copolymer coating doped with molybdate could accelerate the formation of the passive oxide film and have better corrosion prevention efficiencies than PPy‐PAni coating on stainless steel. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40602.  相似文献   

15.
Methyl acrylate/acrylonitrile copolymers (MA/AN) were reactively compatibilized as the dispersed phase into poly(ethylene) (PE) for potential hydrocarbon barrier materials. The MA/AN was made reactive by including p‐aminostyrene (PAS), yielding terpolymers (MA/AN/PAS) with pendant primary amine functionality (number average molecular weight = 65–133 kg mol?1, dispersity (?)=1.83–2.53, molar composition of PAS in copolymer FPAS = 0.03–0.14, molar composition of AN = FAN = 0.27–0.52). The non‐functional MA/AN and amino functional MA/AN/PAS were each melt blended into PE that was grafted with maleic anhydride (PE‐g‐MAnn) at 200 °C at 70:30 wt % PE‐g‐MAnn:co/terpolymer. After extrusion, the dispersed phase particle size (volume to surface area diameter, ) was coarse (12.6 μm) for the non‐reactive blend whereas it was much lower for the reactive blend ( = 1.2 μm). Coarsening after annealing at 150 °C was slow, but the domain sizes increased only slightly for both cases. The reactive blend was deemed sufficiently stable and thus was suitable as a candidate barrier material for further testing against olefins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44177.  相似文献   

16.
Wastewater containing high concentration of ammonium‐nitrogen ( ) is not effectively addressed by biological treatment and when released into water bodies can cause eutrophication. In this study, the removal of from simulated wastewater using chitosan‐coated bentonite (CCB) was investigated. The effects of salt used, pH, CCB dosage, agitation rate, and temperature on the removal of were studied. The highest removal of 67.5% was attained at the following conditions: initial pH 4.0, CCB dose of 8.0 g, agitation rate of 150 rpm, and temperature of 35 °C. Fourier transform infrared analysis indicated two mechanisms: adsorption onto CCB involving hydrogen bonding with hydroxyl groups ( OH) and ion exchange between and cations present in the interlayer of bentonite. Experimental data follows the pseudo‐second‐order kinetic model (R2 = 0.9964) and Koble–Corrigan isotherm (R2 = 0.9705). Thermodynamic studies showed that the adsorption process is spontaneous (ΔG0 < 0), endothermic (ΔH0 > 0) in nature, and leads to an increase in randomness at the solid–solution interface (ΔS0 > 0). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45924.  相似文献   

17.
Polymercaptanized soybean oil (PMSO), the product of a thiol‐ene reaction between soybean oil and hydrogen sulfide, is a material of interest as a lubricant additive and polymer precursor. We investigated with gel permeation chromatography, nuclear magnetic resonance (one‐dimensional and two‐dimensional), gas chromatography–mass spectrometry, and viscometry the changes that occur with PMSO upon heating or ultraviolet irradiation. The observed changes were due to a further thiol‐ene reaction between the thiol groups and the residual unsaturation. The formation of oligomers was a result of new sulfide bridges. Additionally, tetrahydrothiophene moieties were detected. An almost linear increase of the average molecular weight (MW) and the polydispersity index (PDI) was observed upon heat treatment [number‐average MW ( ) = 1180 Da, PDI = 1.32 for PMSO, = 1720 Da, PDI = 2.17 for PMSO that was heated for 1000 h at 130 °C]. PDI correlated best with the z‐average MW. The was the best predictor of the viscosity. For samples with close , the higher PDI corresponded to a higher viscosity index. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46150.  相似文献   

18.
A new polymeric adsorbent material based on polyethylene (PE) was prepared by photografting of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) as a positively chargeable monomer to a PE film. The effects of the experimental parameters, such as the pH value, temperature, and grafted amount on adsorption of chromium(VI) (Cr(VI)) ions were investigated for the DMAEMA‐grafted PE (PE‐g‐PDAMEMA) films. The maximum adsorption capacity was obtained at the initial pH value of 3.0 for a PE‐g‐PDMAEMA film with 1.8 mmol/g and the maximum adsorption capacity obtained was higher than or compatible to those of many of the other polymeric adsorbents prepared for Cr(VI) ions. The adsorption kinetics obeyed the mechanism of the pseudo‐second order kinetic model and adsorption of Cr(VI) ions on PE‐g‐PDMAEMA films was well expressed by the Langmuir isotherm model. A high Langmuir adsorption constant suggests that the adsorption of Cr(VI) ions occurs between protonated dimethylamino groups and ions mainly through the electrostatic interaction. Cr(VI) ions adsorbed were successfully desorbed from a PE‐g‐PDMAEMA film in solutions of NaCl, NH4Cl, NH4Cl containing NaOH, and NaOH and a PE‐g‐PDMAEMA film was regenerated and repeatedly used for adsorption of Cr(VI) ions without appreciable loss in the adsorption capacity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43360.  相似文献   

19.
Two families of acid functional styrene/acrylonitrile copolymers (SAN) for application as dispersed phase barrier materials in poly(ethylene) (PE) were studied. One type is SAN made by nitroxide mediated polymerization (NMP), which was subsequently chain extended with a styrene/tert‐butyl acrylate (S/tBA) mixture to provide a block copolymer (number average molecular weight Mn = 36.6 kg mol?1 and dispersity ? = 1.34, after which the tert‐butyl protecting groups were converted to acid groups (SAN‐b‐S/AA). The other acid functional SAN is made by conventional radical terpolymerization (SAN‐AA). SAN‐AA and SAN‐b‐S/AA were each melt blended with PE grafted with epoxy functional glycidyl methacrylate (PE‐GMA) at 160 °C in a twin screw extruder (70:30 wt % PE‐GMA:SAN co/terpolymer). The non‐reactive PE‐g‐GMA/SAN blend had a volume to surface area diameter = 3.0 μm while the reactive blends (via epoxy/acid coupling) (PE‐GMA/SAN‐b‐SAA and PE‐GMA/SAN‐AA) had = 1.7 μm and 1.1 μm, respectively. After thermal annealing, the non‐reactive blend coarsened dramatically while the reactive blends showed little signs of coarsening, suggesting that the acid/epoxy coupling was effective for morphological stability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44178.  相似文献   

20.
Porous amine‐modified MCM‐41/Nylon‐6 nanocomposite (NH2‐MCM‐41/NY6 NC) was synthesized by a facile solution casting protocol, which was used as an effective adsorbent for the removal of Cu(II) and Cd(II) from aqueous media. The physicochemical properties of NH2‐MCM‐41/NY6 NC were studied by scanning and transmission electron microscopies, thermogravimetric analysis, etc. The influence of pH, adsorbent dose, contact time and initial concentration on adsorption performance were investigated in detail. Kinetic and isotherm parameters were evaluated and the data fitted well to the pseudo‐second order and Freundlich isotherm model, respectively. The maximum adsorption capacities of Cu(II) and Cd(II) were about 35.84 and 27.5 mg·g?1, respectively. The Kd of NH2‐MCM‐41/NY6 NC for Cu(II) (> ) and Cd(II) (> ) ions uptake in aqueous solution, showed very good values. Thermodynamic parameters suggest that the adsorption is a spontaneous process with an endothermic nature. According to the results obtained, we conclude that this novel porous NH2‐MCM‐41/NY6 NC could be used for the removal of heavy metal ions from an aqueous solution. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45383.  相似文献   

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