Removal of ammonium‐nitrogen from aqueous solution using chitosan‐coated bentonite: Mechanism and effect of operating parameters

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.     

Reinforcement of polysiloxane/silica elastomer composite by introduction of sacrificial bonds

It is a challenge to improve tear strength of silicone rubber, especially at high filler loading circumstances. A method is offered here to introduce sacrificial bonds into the system. In particular, amide group was introduced onto the phenyl group of monomer methyl phenyl cyclosiloxane ( first, and this functionalized monomer ( was further used for copolymerization with octamethylcyclotetrasiloxane (D₄) and 2,4,6,8‐tetravinyl‐2,4,6,8‐tetramethyl‐cyclotetrasiloxane ( ). Vulcanizates composed by this new copolymer (1A‐50) which amide group‐containing is 1 wt % and with 50 phr TS‐530 exhibit high tear strength of about 54 N ? mm^?1, which is three times higher than that composed by polydimethylsiloxane (PDMS)/TS‐530 (50 phr). The mechanical test indicates this new copolymer a promising candidate for the construction of high tear resistant silicone rubber, especially at high filler loading circumstances. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46129.     

A new method to determine monomer concentration in the polymer particles of emulsion polymerization systems by dynamic light scattering

In the published article cited above, by considering corrections made on the eq. (19) which will be discussed in the next section, Figure 6 should be replaced with a following new Figure 1. Hence, and values of 0.379 and 5.68 mol.dm^?3, respectively, on pages 1055, 1061, and 1062 should be changed to their accurate values of 0.426 and 5.29 mol.dm^?3, respectively.     

Indirect effect of polyvinylpyrrolidone and cetyltrimethylammonium bromide on UV‐blocking efficiency of TiO2@PVP‐CTAB@SiO2 core‐shell nanohybrid particles

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.     

Ageing effects on the creep‐recovery behavior of blown extruded low density polyethylene film

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.     

Spontaneous formation of gold microplates during reduction‐coupled removal of noble metals using Dowex M4195 resin

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.     

Synthesis and characterization of PEDOT derivative with carboxyl group and its chemo sensing application as enhanced optical materials

Poly(4‐(((2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐2‐yl)methoxy)methyl)benzoic acid) (PEDOT‐Ph‐COOH) was facilely synthesized by the direct electropolymerization of 4‐(((2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐2‐yl)methoxy)methyl)benzoic acid (EDOT‐Ph‐COOH) in CH₂Cl₂‐Bu₄NPF₆ (0.10 M) system, and the PEDOT‐Ph‐COOH films were systematically investigated. The results displayed that the film had excellent reversible redox activities, good electrochemical performance, and rough and compact surface. Finally, the PEDOT‐Ph‐COOH film was used as an optical chemo‐sensor for the highly selective and sensitive detection of F^?, , , , Cu²⁺, and Fe³⁺ in dimethyl sulfoxide. Satisfactory results indicated that optical chemo‐sensor based on PEDOT‐Ph‐COOH possessed an excellent sensing performance and enhanced optical response, and it might be as potential promising materials, such as electrochromic devices, supercapacitors and so on. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41559.     

Investigation and modelling of damping mechanisms of magnetorheological elastomers

Damping in MREs is considered to be ascribed to viscous flow of the rubber matrix, interfacial damping at the interface between the magnetic particles and the matrix and magnetism induced damping. In this study, individual components in MREs that contribute to material damping were investigated. A model was developed to include viscous flow of the rubber matrix, interfacial damping and magnetism induced damping to give the total damping capacity of MREs ( )It was found that depends on frequency, iron sand content, strain amplitude and is independent of the applied magnetic field over saturation magnetization. The proposed model was assessed experimentally using a series of isotropic and anisotropic MREs. Comparison between tan δ with showed that matched the experimental trends with average percentage difference of 8.1% and 21.8% for MREs with modified iron sand unmodified iron sand, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43247.     

Cross‐linked chitosan beads for phosphate removal from aqueous solution

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 (Q_m) for PNP ranged from 0.30 to 0.52 mmol g^?1 and (ii) Q_m values for the bead systems with ranged from 22.4–52.1 mg g^?1 for these conditions. GA cross‐linked beads reveal greater Q_m values for PNP while EP cross‐linked beads showed greater Q_m 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.     

Compressive shape memory behavior of spring‐shaped polylactic acid alloy type

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 (R_r), shape fixing ratio (R_f), and shape recovery force (F_r)], the samples programmed at three different temperatures (T_p) of 70, 80, and 90 ° and at various recovery temperatures (T_r) over 40 to 90 ° , were studied. In general, the spring made with PT7030 showed higher R_r, R_f, and F_r values. The highest R_r (99%) was obtained at programmed temperature (T_p) of 70 ° and recovery temperature (T_r) of 90 ° . However, the R_r value for this spring programmed at 70 ° and recovered near body temperature was 50% with F_r of 1.4 N. Furthermore, the highest F_r (15.6 N) was observed in the spring made of PT7030 programmed at 80 ° and recovered at T_r of 78 ° . © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45115.     

Synthesis of aminated glycidyl methacrylate grafted rice husk and investigation of its anion‐adsorption properties

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.     

Vibration damping characterization of linseed oil‐based elastomers for its effectiveness to attenuate structural vibration

Vibration damping properties of elastomers prepared from linseed oil were characterized by dynamic mechanical analyzer in a temperature range of ?50 to 100°C and frequency range of 5 Hz to 1 kHz. The maximum damping loss factor, varies from 0.78 to 1.32, the room temperature (25°C) loss factor, in the range of 0.56–1.08 and the temperature range ( ) for effective damping varies from 63°C to 74.4°C in different elastomers. The elastomers behave as a good vibration damper both in lower and higher frequency range. Thus these elastomers exhibit good damping behavior in a wide range of temperature and frequency, a primary requirement for practical damping applications. A modal constrained layer damping system constructed utilizing these elastomers exhibits its potentiality to attenuate structural vibrations with respect to mild steel bare plate resonator under laboratory fabricated testing methodology. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3611–3623, 2013     

Heat‐ and light‐induced thiol‐ene oligomerization of soybean oil‐based polymercaptan

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.     

Reactive compatibilization of poly(methyl acrylate‐ran‐acrylonitrile)/poly(ethylene) blends through amine–anhydride coupling

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 F_PAS = 0.03–0.14, molar composition of AN = F_AN = 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.     

Mechanism of internal and external electron donor effects on propylene polymerization with MgCl2‐supported Ziegler–Natta catalyst: New evidences based on active center counting

Two TiCl₄/Di/MgCl₂ type supported Ziegler–Natta catalysts were prepared by loading dibutylphthalate or dicyclopentyldimethoxysilane (DCPDMS) (internal donor, Di) and TiCl₄ on activated δ‐MgCl₂ in sequence, and a blank catalyst was prepared by loading TiCl₄ on the same δ‐MgCl₂ without adding Di. These catalysts have similar specific surface area and pore size distribution, thus form a suitable base for comparative studies. Propylene polymerization with the catalysts was conducted in n‐heptane slurry using triethylaluminum (TEA) as cocatalyst, and the effects of Di as well as De (external donor, in this work it was DCPDMS) on the number of active centers, the distribution of active centers among three polypropylene (PP) fractions (isotactic, medium isotactic, and atactic PP chains), and chain propagation rate constants of the PP fractions were studied by counting the number of active centers in the PP fractions using a method based on selective quench‐labeling of the propagation chains by 2‐thiophenecarbonyl chloride. When De was not added in the polymerization, introducing a phthalate type Di in the catalyst evidently changed the active center distribution by enhancing the proportion of active centers producing isotactic PP (iPP) ( ), but scarcely changed reactivities of the three groups of active centers forming the three fractions. When the De was added in the polymerization system with TiCl₄/phthalate/MgCl₂ catalyst, further shifting of active center distribution in favor of took place, meanwhile reactivities of the three groups of active centers also remarkably changed in favor of . Mutual effects of these changes led to overwhelming dominance of iPP production in the TiCl₄/Di/MgCl₂–TEA/De system (Di = phthalate, De = alkoxysilane). In contrast, though using alkoxysilane as Di also caused shifting of active center distribution in favor of when De was not added, addition of alkoxysilane De caused reverse shifting of active center distribution in favor of those producing PP of lower stereoregularity. This unfavorable change largely counteracted the reactivity changes in favor of caused by the De, rendering the catalytic system rather poor isospecificity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46605.     

Nucleation parameter and size distribution of critical nuclei for nonisothermal polymer crystallization: The influence of the cooling rate and filler

The nucleation parameter K_g of filled PP, HDPE, and PA6 is determined through nonisothermal DSC measurements. A novel method is proposed for the determination of the size distribution of critical nuclei, where the most commonly found fraction was obtained as a peak value. The models are tested at different cooling rates and different filler loadings. K_g varies up to a certain cooling rate and afterwards remains constant. The introduction of talc in PP and HDPE facilitates nucleation and thus reduces K_g. An opposite trend occurs upon the addition of bentonite in PA6. The changes of K_g and are reflected on sample morphology, as confirmed with SAXS. The ratio between the final crystal thickness and amounts to approx. 2 and thus agrees well with the one listed in literature. The simple linear correlations of the obtained K_g are established with Young's modulus and yield stress. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41433.     

Copolymers from methyl methacrylate and butyl acrylate with hyperbranched architecture

This is a first report of the synthesis and characterization of acrylic copolymers from methyl methacrylate (MMA) and butyl acrylate (BA) with hyperbranched architecture. The copolymers were synthesized using a free radical polymerization (Strathclyde method) in emulsion technique. Divinyl benzene was used as the brancher which acted as a comonomer and 1‐dodecanethiol was used as a chain terminating agent. A linear copolymer from MMA and BA was also synthesized for comparison. The hyperbranched architecture was established from spectroscopic and rheological measurements. The gel permeation chromatography showed all hyperbranched copolymers were low molecular weight with lower polydispersity index (PDI) ( 23,000, PDI ～ 2.00) compared to the linear grade ( 93,000, PDI ～ 2.20). They were more spherical and achieved lower viscosity (yet higher solubility, >90%) than the linear grade (<50%) which was mostly open ended. Lower viscosity at equivalent solid content made the hyperbranched polymers a potential binder for adhesive and coating application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45356.     

A novel porous nanocomposite of aminated silica MCM‐41 and nylon‐6: Isotherm,kinetic, and thermodynamic studies on adsorption of Cu(II) and Cd(II)

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 K_d 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.     

Detecting at‐Most‐m Changes in Linear Regression Models

In this article, we provide a new procedure to test for at‐most‐ changes in the time‐dependent regression model , that is, β ₁ =  β ₂ = ? =  β _T under the no‐change null hypothesis against the alternative if and β ^(j) ≠  β ^(?) for some with . Our procedure is based on weighted sums of the residuals, incorporating the possibility of changes. The weak limit of the proposed test statistic is the sum of two double‐exponential random variables. A small Monte Carlo simulation illustrates the applicability of the limit results in case of small and moderate sample sizes. We compare the new method to the cumulative sum control chart (CUSUM) and standardized (weighted) CUSUM procedures and obtain the power curves of the test statistics under the alternative. We apply our method to find changes in the unconditional four‐factor capital asset pricing model.     

Viscoelastic properties of borax loaded CMC‐g‐cl‐poly(AAm) hydrogel composites and their boron nutrient release behavior

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.