Effects of dodecyl amine functionalized graphene oxide on the crystallization behavior of isotactic polypropylene

Dodecyl amine functionalized graphene oxide (DA‐GO)/isotactic polypropylene (iPP) nanocomposites were prepared via solution mixing method. Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and X‐ray photoelectron spectroscopy (XPS) verified that the DA was successfully grafted onto the surface of graphene oxide. The crystallization behavior of iPP/DA‐GO nanocomposites was investigated by differential scanning calorimetry (DSC) and polarized optical microscope (POM). The DSC results of both isothermal and non‐isothermal crystallization process indicated that the addition of DA‐GO can decrease the half‐time crystallization (t_1/2) and elevate crystallization peak temperature (T_p) of iPP. The results of isothermal crystallization kinetics showed that the overall crystallization rates of iPP/DA‐GO nanocomposites, especially with higher DA‐GO content, were much faster than that of neat iPP. During the non‐isothermal crystallization process, the nucleation ability (Φ) of nanocomposites containing 0.05, and 0.5 wt % DA‐GO were 0.83 and 0.69, respectively. And the crystallization activation energy of iPP decreased from 348.7 (neat iPP) to 309.2 and 283.1 kJ/m 2 by addition of 0.05 and 0.5 wt % DA‐GO, respectively. The decrease of Φ and indicated DA‐GO has strong heterogeneous nucleation effect and can promote the crystallization of iPP significantly. Additionally, POM micrographs showed the DA‐GO in iPP matrix can form more nucleation sites for the spherulite growth. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40000.     

Ultrasound assisted continuous‐mixing for the preparation of PP/SEBS/OMMT ternary nanocomposites

Polypropylene (PP)/polystyrene‐block‐poly(ethylene‐co‐butylenes)‐block‐polystyrene (SEBS)/organo‐montmorillonite (OMMT) nanocomposites of varying concentrations of maleic anhydride‐grafted polypropylene (PP‐g‐MA) were prepared by continuous mixing assisted by ultrasonic oscillation. The structure and morphology of nanocomposites were investigated by X‐ray diffraction (XRD), transmission electron microscopy, and scanning electron microscopy. It was found that both PP‐g‐MA and ultrasonic oscillation could enhance the intercalation and exfoliation of OMMT in PP matrix. Meanwhile, the formation of PP could be induced by ultrasonic irradiation at a power of more than 540 W. Rheological properties including complex viscosity, storage, and loss modulus of nanocomposites were increased after adding PP‐g‐MA or ultrasonic treatment. The results of mechanical properties showed that PP‐g‐MA could improve the tensile strength and tensile modulus of nanocomposites, but with the sacrifice of impact strength. This problem could be improved by ultrasound due to the reduced particle size of SEBS. However, the mechanical properties would be reduced by ultrasonic treatment with higher intensity due to the polymer degradation. Therefore, the synergistic effect of both compatibilizer and ultrasound should account for the balance between toughness and stiffness of PP/SEBS/OMMT ternary nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41202.     

Electrical properties and the role of inhomogeneities at the polyvinyl alcohol/n‐inp schottky barrier interface

In this work, we have investigated the electrical properties of Au/n‐InP contacts with a thin layer of polyvinyl alcohol (PVA) as an interlayer. The current–voltage (I–V) and capacitance–voltage (C–V) measurements are carried out in the temperature range of 175–425 K. The Au/PVA/n‐InP Schottky structure show nonideal behaviors and indicates the presence of a nonuniform distribution of interface states. The temperature dependent interface states densities (N_SS), ideality factor and barrier height are obtained. An abnormal decrease in zero‐bias barrier height (BH) and increase in the ideality factor ( ) with decreasing temperature have been explained on the basis of the thermionic emission theory with Gaussian distribution (GD) of the BHs due to the BH inhomogeneities. The experimental I–V characteristics of Au/PVA/n‐InP Schottky diode has revealed the existence of a double GD with mean BH values of ( ) of 1.246 and 0.899 eV and standard deviation ( ) of 0.176 and 0.137 V, respectively. Consequently, the modified conventional activation energy versus plot gives and Richardson constants ( ) and the values are 1.17 and 0.71 eV and 9.9 and 6.9 A/cm² K², respectively, without using the temperature coefficient of the BH. The effective Richardson constant value of 9.9 A/cm² K² is very close to the theoretical value of 9.4 A/cm² K² for n‐InP. The discrepancy between Schottky barrier heights estimated from I–V and C–V measurements is also discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39773.     

Modeling of tensile strength in polymer particulate nanocomposites based on material and interphase properties

In this work, a simple model is presented to determine tensile/yield strength in polymer nanocomposites containing spherical nanofillers based on material and interphase properties. The accuracy of the proposed model is estimated by comparing with the experimental strength of several samples from the literature. In addition, the effects of thickness (t) and tensile strength (σ_i) of the interphase as well as the radius (R) and volume fraction ( ) of the nanoparticles on the tensile strength are explained according to the proposed model. The high level of nanoparticle strength (more than 100 GPa) commonly leads to overestimates of the tensile strength of nanocomposites, whereas the assumption of correct interphase properties produces accurate calculations. The tensile strength of nanocomposites does not change at σ_i < 38 MPa, while it increases by 140% at t = 20 nm and σ_i = 90 MPa. However, a maximum 14% growth in tensile strength is obtained with the optimum values of = 0.04 and R = 10 nm. Therefore, the concentration and size of the nanoparticles have minor effects on the tensile strength of nanocomposites, but the major influences of interphase thickness and strength are pronounced. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44869.     

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.     

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.     

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.     

The physical and mechanical properties of beta‐nucleated polypropylene/montmorillonite nanocomposites

Polypropylene (PP) and polypropylene/polypropylene‐g‐maleic anhydride/ organomontmorillonite (PP/PP‐g‐MA/OMMT) nanocomposites were modified with 0.05 to 0.3% (w/w) of the aryl amide β‐nucleator to promote the formation of hexagonal crystal modification (β‐phase) during melt crystallization. The nonisothermal crystallization behavior of PP, PP/PP‐g‐MA/OMMT and β‐nucleated PP/PP‐g‐MA/OMMT nanocomposites were studied by means of differential scanning calorimetry. Structure‐property relationships of the PP nanocomposites prepared by melt compounding were mainly focused on the effect and quantity of the aryl amide nucleator. The morphological observations, obtained from scanning electron microscopy, transmission electron microscopy and X‐ray diffraction analyses are presented in conjunction with the thermal, rheological, and mechanical properties of these nanocomposites. Chemical interactions in the nanocomposites were observed by FT‐IR. It was found that the β‐crystal modification affected the thermal and mechanical properties of PP and PP/PP‐g‐MA/OMMT nanocomposites, while the PP/PP‐g‐MA/OMMT nanocomposites of the study gained both a higher impact strength (50%) and flexural modulus (30%) compared to that of the neat PP. β‐nucleation of the PP/PP‐g‐MA/OMMT nanocomposites provided a slight reduction in density and some 207% improvement in the very low tensile elongation at break at 92% beta nucleation. The crystallization peak temperature (T_cp) of the PP/PP‐g‐MA/OMMT nanocomposite was slightly higher (116°C) than the neat PP (113°C), whereas the β‐nucleation increased the crystallization temperature of the PP/PP‐g‐MA/OMMT/aryl amide to 128°C, which is of great advantage in a commercial‐scale mold processing of the nanocomposites with the resulting lower cycle times. The beta nucleation of PP nanocomposites can thus be optimized to obtain a better balance between thermal and mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

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.     

Isothermal crystallization kinetics of poly(lactic acid)/synthetic mica nanocomposites

The isothermal crystallization kinetics of PLA/fluoromica nanocomposites was studied. Three types of synthetic mica at three concentrations (2.5, 5.0, and 7.5 wt % mica) were used and the effect of these micas on the crystallization and thermal properties of PLA was investigated by differential scanning calorimetry (DSC). The Avrami and Hoffman‐Weeks equations were used to describe the isothermal crystallization kinetics and melting behavior. Addition of these micas to the PLA matrix increased the crystallization rate, and this effect depended on the mica type and concentration. While the nonmodified Somasif ME‐100 exerted the smallest effect, the effect observed for the organically modified Somasif MPE was the most pronounced. The lower half‐time of crystallization t_1/2 was around 3 min for the PLA/Somasif MPE nanocomposites containing 7.5 wt % of filler at 90°C, which is about 16 min below that found for neat PLA. The equilibrium melting temperature ( ) of PLA were estimated for these systems, showing an increase in the composites and an increase with increasing loading, except for PLA/Somasif MPE, in which the increase of the mica content decreased about 5°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40322.     

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.     

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.     

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.     

Preparation and characterization of polysiloxane networks containing metallic platinum particles

Polysiloxane networks obtained via cross‐linking of D₄/V₄ polysiloxane served as matrices for incorporation of metallic Pt particles. D₄/V₄ polymer used in the crosslinking was synthesized by equilibrium cationic ring‐opening polymerization of the corresponding cyclotetrasiloxane monomers. Linear (^HMM^H) or cyclic ( ) hydrosiloxanes, at different hydrosiloxane to D₄/V₄ molar ratios, were applied as crosslinking agents. Platinum species were introduced into the crosslinked products from PtCl₄ solution in THF or in isopropyl alcohol via the reduction of Pt⁴⁺ to Pt⁰ in the presence of active Si‐H sites. Various analytical techniques: UV‐vis and FTIR spectroscopy, swelling measurements, XRD, SEM, and thermogravimetric analysis were applied to control the progress of the reaction or to characterize the intermediate or final products. IR spectroscopy allowed to determine the efficiency of cross‐linking process and to investigate the consumption of un‐reacted Si‐H groups accompanying the reduction of platinum ions. XRD studies confirmed the incorporation of metallic platinum into all systems. Good thermal stability of obtained products was found using thermogravimetric analysis. According to SEM investigations, the applied network as well as the solvent used in the reduction process influenced the dispersion of metallic particles on the surface of the matrices. The obtained Pt‐systems exhibited mainly redox activity in catalytic isopropyl alcohol conversion used as a test reaction. Significant differences in catalytic properties between systems containing different matrices were observed. The promoting effect on the catalytic activity was found in the case of C‐P type support, i.e. the polysiloxane network obtained using the cyclic hydrosiloxane as the crosslinking agent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43096.     

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.     

Influence of 2,2′,6,6′‐tetramethyl biphenol‐based anion‐exchange membranes on the diffusion dialysis of hydrochloride acid

Quaternary ammonium functionalized poly(arylene ether) (QPAE‐Br) membranes based on 2,2′,6,6′‐tetramethyl biphenol for diffusion dialysis (DD) were designed and successfully fabricated via nucleophilic substitution polycondensation, bromination, film casting, and quaternization. The structures, thicknesses, ion‐exchange capacities (IECs), water uptakes, swelling ratios, ion conductivities, and mechanical properties of QPAE‐Br were used to characterize the membranes. The influence of the membrane structures on the DD performances was investigated by DD tests of simulated industrial pickling wastewater (1 mol/L HCl, 0.1 mol/L FeCl₂). The DD results show QPAE‐a (IEC = 1.51 mmol/g) as the best DD candidate. Predialysis treatments further improved the DD performances of QPAE‐Br. QPAE‐a exhibited an excellent proton diffusion coefficient ( ) of 0.033 m/h and a high separation factor (S) of 95.45 after the predialysis treatment at room temperature; these values were much higher than those of the commercial DF‐120B membrane (0.004 m/h for and 24.3 for S at 25 °C) and other reported DD membranes. QPAE‐a has great potential for acid recovery via DD. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45333.     

Effect of Ca2+ induced crosslinking on the mechanical and barrier properties of cast alginate films

The use of alginate as a coating material for packaging applications is currently limited due to its difficult processability and high moisture sensitivity. Therefore, this study addresses the crosslinking and scale‐up to a continuous application. Three different crosslinking agents were applied: CaCl₂ with ethylene diamine tetraacetic acid and two low soluble salts (CaHPO₄ and CaCO₃). Those were incorporated by internal setting in an alginate matrix with varying Ca²⁺ concentration ( ) and ratio. With the addition of Ca²⁺, the tensile strength and elongation at break of the cast alginate films increased. This was optimal for a of 0.010–0.015 g (g alginate)^?1 dependent on the crosslinking agent. The decrease in water vapor and oxygen permeability due to crosslinking was independent of the crosslinking agent. However, the optimal aiming to decrease permeability was different for the crosslinking agents: CaHPO₄ showed best results at a of 0.010 g (g alginate)^?1, CaCl₂ at 0.012 g (g alginate)^?1, and CaCO₃ at 0.027 g (g alginate)^?1. Upon all analyzed properties CaHPO₄ was the most promising crosslinking agent for alginate. Moreover, selected alginate formulations were successfully processed in a continuous lacquering plant. The produced two‐layer systems have very low oxygen permeabilities which can be further reduced by crosslinking. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45754.     

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.     

Sorption and thermal properties of strongly basic cross‐linked ionic polymer modified with Cr(III) compounds

AV‐17(Cr) material was prepared by modifying a commercial polymer AV‐17 (initially bearing R4N⁺ functional groups) with Cr(III) compounds was investigated. Comparative isotherms characterizing the and ion sorption from solution with pH values of 3 and 8, respectively, at 19°C and 60°C, were obtained using the raw AV‐17(Cl) and the modified AV‐17(Cr) material. The sorption process on AV‐17(Cr) takes place through the coordination of Cr(VI) ions with Cr(III) ions, while on AV‐17(Cl) it is due to an ion exchange mechanism. The sorption isotherms obtained in pH 8 solutions fit perfectly the Langmuir model. The thermodynamic functions ΔG, ΔH, and ΔS characteristic to the adsorption of ions from K₂CrO₄ solutions with pH = 8 were calculated. The active sites belonging to the AV‐17(Cr) material were identified as jarosite type compounds of Cr(III). SEM images show that the Cr(III) compounds are present in the form of ultrafine particles located on the surface and within the bulk phase of the polymer granules. Comparative thermal degradation process of both the AV‐17(Cr) and the AV‐17(Cl) material was conducted in air and in an inert atmosphere (He). The thermal degradation mechanism of sorbent AV‐17(Cr) and exchanger AV‐17(Cl) is proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41306.     

Adsorption of Hg(II) in aqueous solutions using mercapto‐functionalized alkali lignin

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.