Graft Copolymerization Reaction Research Articles

Synthesis and characterization of carboxyl terminated poly(methacrylic acid) grafted chitosan/bentonite composite and its application for the recovery of uranium(VI) from aqueous media

A novel adsorbent poly(methacrylic acid)-grafted chitosan/bentonite (CTS-g-PMAA/Bent) composite was prepared through graft copolymerization reaction of methacrylic acid and chitosan in the presence of bentonite (Bent) and N,N′- methylenebisacrylamide as a crosslinker. The composite was well characterized using FTIR, XRD, XPS, SEM-EDS, surface area and zeta potential analyzers. The adsorption behavior of the composite toward uranium(VI) from aqueous media was studied under varying operating conditions of pH, concentration of U(VI), contact time, adsorbent dose and temperature. The optimum pH range for U(VI) adsorption was 5.5 at 30 °C. Concentration and temperature dependent rate constants were evaluated using pseudo-second-order kinetic model. The equilibrium data were correlated with the Langmuir isotherm model with an endothermic behavior. The equilibrium U(VI) sorption capacity was estimated to be 117.2 mg g−1 at 30 °C. For the quantitative recovery of 100 mg L−1 U(VI) from 1.0 L simulated nuclear industry wastewater, a minimum adsorbent dosage of 2.0 g CTS-g-PMAA/Bent was required. The calculated energy of activation (Ea = 47.83 kJ/mol) was positively correlated with chemical adsorption process. The values of enthalpy, entropy and free energy of activation were calculated to explain the nature of adsorption process. Adsorption–desorption experiments over four cycles illustrate the feasibility of the repeated uses of this composite for the extraction of U(VI) from aqueous solutions.

Thorium(IV) Removal and Recovery from Aqueous Solutions using Tannin-Modified Poly(glycidylmethacrylate)-Grafted Zirconium oxide Densified Cellulose

A novel adsorbent, tannin-modified poly(glycidylmethacrylate)-grafted zirconium oxide-densified cellulose (TMPGZDC) was synthesized by graft copolymerization reaction of glycidylmethacrylate onto z...

Graft Copolymerization of Methyl Acrylate onto Cellulosic Biofibers: Synthesis, Characterization and Applications

Graft copolymerization of cellulosic biopolymers with synthetic polymers is of enormous interest because of its application in biofiltration, biosorption, biomedical, biocomposites and various other eco-friendly materials. Synthesis of graft copolymers of methyl acrylate onto mercerized Grewia optiva biofibers using ferrous ammonium sulfate–potassium per sulfate as redox initiator in air was carried out. Different reaction parameters such as amount of solvent, monomer concentration, initiator molar ratio, reaction time and reaction temperature were optimized to get the maximum percentage of grafting. The graft copolymers thus formed were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis and differential thermogravimetric techniques. A plausible mechanism for explanation of the graft copolymerization reactions pattern shown is offered. The effect of grafting percentage on the physico–chemical properties of raw as well as grafted Grewia optiva biofibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance. Green polymer composites were also successfully prepared through compression molding technique by using grafted Grewia optiva biofibers as reinforcement.

Effect of surfactant on porosity and swelling behaviors of guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite superabsorbent hydrogels

Novel fast-swelling porous guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite (GG-g-P(NaA-co-St)/APT) superabsorbent hydrogels were prepared by simultaneous free-radical graft copolymerization reaction of guar gum (GG), partially neutralized AA (NaA), styrene (St) and attapulgite (APT) using N,N'-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution and the surfactant self-assembling templating pore-forming technique. Fourier transform infrared (FTIR) spectroscopy confirmed that the surfactant could be removed from the final hydrogel product by methanol/water (8:1, v/v) washing process and the surfactant only act as micelle template to form pores. The effect of surfactant type on the porous microstructure of the hydrogel was assessed by field emission scanning electron microscope (FESEM). It was shown that incorporation of proper amount of anionic surfactant sodium n-dodecyl sulfate (SDS) in the gelling process of the hydrogel can obviously enhance the swelling capacity and initial swelling rate. The salt-sensitivity of the SDS-added hydrogel in distilled water and 15 mmol/L NaCl, CaCl(2) solution or 15 mmol/L NaCl and CaCl(2) solution was investigated, and it was found that the swelling-deswelling capability is quite reversible. A similar reproducible on-off switching behavior was observed in the 1 mmol/L solution of phosphate buffer at pH 2.1 and 7.4.

Synthesis and characterization of a novel graft copolymer containing carboxyl groups and its application to extract uranium(VI) from aqueous media

AbstractA novel poly(methacrylic acid)‐grafted‐cellulose/bentonite (Cellu‐g‐PMAAc/Bent) superabsorbent composite was prepared through graft copolymerization reaction among cellulose, methacrylic acid, and bentonite in the presence of N,N′‐methylenebisacrylamide as a crosslinker and potassium peroxydisulphate as an initiator. The structural and morphological characteristics of the graft copolymer were determined using Fourier transform infrared spectra, scanning electron microscope‐energy dispersion analysis, and X‐ray diffraction. The effectiveness of the Cellu‐g‐PMAAc/Bent, as adsorbent for the removal and recovery of uranium(VI) from aqueous media, was studied. The effects of pH, contact time, and initial sorbate concentration were studied to optimize the conditions for maximum adsorption. The adsorption process, which was pH dependent, shows maximum removal (>99.0%) at pH 6.0. Kinetic study showed that 180 min of contact at 100 mg/L could adsorb about 99.2% of U(VI) onto Cellu‐g‐PMAAc/Bent. A pseudosecond‐order kinetic model successfully described the kinetics of sorption of U(VI). Adsorption equilibrium data were correlated with the Langmuir, Freundlich, and Redlich–Peterson isotherm models. The best fit was obtained with Freundlich model. Desorption of U(UI) was studied by using 0.1M HCl. Adsorption/desorption for more than six cycles showed the possibility of repeated use of this graft copolymer for the recovery of U(VI) from aqueous solutions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The Compounding and Application Mechanism of Polycarboxylate-Based Superplasticizers in the Self-Compacting Concrete

Polycarboxylate-based superplasticizers are synthesized by radical graft copolymerization reaction, and the products are divided into ester series (PC-1) and ether series (PC-2) on the basis of different big monomers. This article studies on influence of the different composition and dosages of the synthetic superplasticizers in the self-compacting concrete (SCC). The results show that the requirements of SCC workability can be achieved through simple adjustment kinds and dosages of the synthetic superplasticizers under the given mix proportions and the raw materials. And the main mechanism of the polycarboxylate-based superplasticizers is steric hindrance effect.

Graft copolymerization of methyl methacrylate onto cellulosic biofibers

AbstractIn this article, we have used the potassium persulfate to initiate the graft copolymerization of methyl methacrylate onto cellulosic biofibers in aqueous medium. Different reaction parameters, such as reaction time, initiator molar ratio, monomer concentration, amount of solvent, and reaction temperature, were optimized to get the maximum percentage of grafting (50.93%). The graft copolymers thus formed were characterized by Fourier transform infrared, scanning electron microscopy, X‐ray diffraction, and thermogravimetric, differential thermal analysis, and derivative thermogravimetric techniques. A mechanism is proposed to explain the generation of radicals and the initiation of graft copolymerization reactions. On grafting, percentage crystallinity decreases with reduction in its stiffness and hardness. The effect of grafting percentage on the physicochemical properties of raw as well as grafted fibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Utilization of starch and montmorrilonite for the preparation of superabsorbent nanocomposite

AbstractStarch and montmorrilonite (MMT) were used as raw materials for synthesizing starch‐graft‐poly[acrylamide (AM)–acrylic acid (AA)]/MMT superabsorbent nanocomposite by graft and intercalation copolymerization reaction of starch, AM, and AA in the presence of organic MMT micropowder in aqueous solution. Major factors affecting water absorbency such as weight ratio of monomers to starch, weight ratio of AM to AA, neutralization degree of AA, amount of crosslinker, initiator, and MMT were investigated. The superabsorbent nanocomposite synthesized under optimal synthesis conditions exhibits absorption of 1120 g H2O/g sample and 128 g H2O/g sample in deionized water and in 0.9 wt % NaCl solution, respectively. IR spectra showed that the graft copolymerization between OH groups on MMT and monomers took place during the reaction, and that crystal interlayer was pulled open in the superabsorbent nanocomposite. X‐ray diffraction analysis showed that the crystal interlayer of MMT was pulled open to 2.73 nm, and thus formed nanometer exfoliation composite material. Thermogravimetric analysis showed that starch‐graft‐poly (AM–AA) superabsorbent nanocomposite (8 wt % MMT) has good thermal stability. This superabsorbent nanocomposite with excellent water absorbency and water retention, being biodegradable in nature, economical and environment friendly, could be especially useful in industry, agricultural, and horticultural applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Mathematical modeling of the graft reaction between polystyrene and polyethylene

Polystyrene (PS) and polyethylene (PE) are two major components of household plastic waste whose blends are immiscible. Recycling them together is an attractive option that requires a compatibilization process to improve the blend mechanical properties. If a PE/PS copolymer is added or formed in situ, it may act as compatibilizer. The structure and molecular properties of this copolymer are key factors to assure its effectivity as a compatibilizer. In this work, we study the graft copolymerization reaction between polystyrene and polyethylene using the catalytic system composed of AlCl3 and styrene. We develop a model of this process which considers that PE/PS grafting and PS degradation occur simultaneously. We propose a kinetic mechanism for the whole process and apply the method of moments to solve the mass balance equations. The model is able to calculate average molecular weights as well as the amount of grafted PS. It accurately describes the available experimental data, constituting a valuable tool for simulation and optimization purposes.

Investigation on Poly(methacrylic acid)-Grafted Cellulose/Bentonite Superabsorbent Composite: Synthesis, Characterization, and Adsorption Characteristics of Bovine Serum Albumin

Investigation on adsorption behavior of bovine serum albumin (BSA) on superabsorbent composite is critical for many analytical and biomedical applications. In this study, a novel poly(methacrylic acid)-grafted cellulose/bentonite (PMAA-g-Cell/Bent) superabsorbent composite was synthesized by graft copolymerization reaction of methacrylic acid on cellulose (Cell) in the presence of bentonite (Bent) using N,N′-methylenebisacrylamide as a cross-linker. The original Cell and Bent and composite were analyzed using FTIR, XRD, SEM, TG, and potentiometric titrations. The ability of the composite to adsorb BSA from aqueous solutions has been studied at different optimized conditions. The optimum pH range for the maximum uptake of BSA was 4.5. Maximum adsorption of the BSA, i.e., 99.7%, was achieved from an initial concentration of 10.0 mg/L using 1.0 g composite at pH 4.0. The equilibrium time of adsorbing BSA was about 3 h. Experimental kinetic data were tested with pseudo-first-order and pseudo-second-order kine...

Poly(vinylidene fluoride)-graft-poly(2-hydroxyethyl methacrylate): a novel material for high energy density capacitors

We report the graft copolymerization synthesis of novel high dielectric constant HEMA (2-hydroxyethylmethacrylate)-graft-poly(vinylidene fluoride) (PVDF) copolymers for potential applications in high energy density capacitors. In the present study the graft copolymerization reaction was introduced by irradiation (electron beam) treatment of the PVDF polymer powder. The chemical changes in the PVDF polymers after HEMA grafting were monitored and the results were evaluated by FTIR, DSC, TGA and contact angle measurement. An analysis is presented on the effectiveness of this approach as a function of electron beam operating variables including radiation dose, reaction time, reaction temperature, monomer concentration and effect of solvent. The PHEMA-g-PVDF copolymers demonstrate improved dielectric properties such as high dielectric constant, lower leakage and low dielectric loss as compared to pristine PVDF. Correlation of dielectric properties with the graft copolymerization reaction mechanism was discussed.

Polystyrene grafted polyvinylidenefluoride copolymers with high capacitive performance

Electroactive materials are of great interest for high performance capacitive behavior due to their relaxed ferroelectric properties. In this work, we studied the dielectric properties of poly(vinylidene fluoride) (PVDF) grafted with polystyrene (PS) by electron beam radiation induced free radical graft copolymerization reaction in solution. The dielectric constant of polystyrene grafted PVDF copolymers reaches about 90 at 100 Hz at room temperature representing more than seven times increment compared with the pristine PVDF matrix. The dielectric loss of 0.005 at 1 KHz can be achieved. Correlation of the dielectric properties with the graft copolymerization reaction mechanism was discussed. This route represents one of the most effective techniques to synthesize potential graft copolymers with desirable dielectric properties in a wide frequency range for energy storage applications.

Graft polymerization of acrylonitrile onto paper and characterization of the grafted product

The chemical graft copolymerization reaction of acrylonitrile (AN) onto paper sheet was performed. The effect of initiator concentration, monomer concentration, and temperature on the reaction rate was studied. The reaction rate equation of the graft copolymerization reaction is found to be RP = K2 [initiator]0.54[monomer]1.13. The apparent activation energy (Ea) of the copolymerization reaction is found to be 35.99 KJ/mol. The infrared characteristic absorption bands for cellulosic paper structure and the paper gr-AN are studied. Tensile break load, porosity, and burst strength were measured for the grafted and pure paper sheet. It was found that the mechanical properties are improved by grafting. The chemical resistance of the graft product against strong acid (HCl), strong alkali (NaOH), polar and nonpolar solvents was investigated. It was found that the resistance to these chemicals is enhanced by grafting. From the TGA and DTA data, it is clear that the grafted paper sheet is more thermally stable than pure paper sheet. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation of agriculture residue based adsorbents for heavy metal removal

Guava seeds, a byproduct produced during guava juice processing, are currently of no economic value. In the present work two different types of adsorbents have been prepared from raw guava seeds, namely chemically activated guava seed carbon (AGSC) using zinc chloride and chemically modified guava seeds (MGS) through graft co-polymerization reaction. The adsorption capacity of both adsorbents towards Ni(II) has been investigated. It has been found that the equilibrium adsorption capacity is a function of initial pH, contact time, initial nickel(II) concentration, and adsorbent dosage. The optimum pH for both adsorbents was found to be 6. Both Langmuir and Freundlich models best describe the equilibrium experimental data. The maximum adsorption capacities for AGSC and MGS are 18.05 and 32.05 mg/g respectively. The kinetic experimental data were fitted well by the second-order model. The natures of the main functional groups which may be present on raw guava seeds and MGS have been investigated by infrared (IR) studies.

Kinetics of Grafting Polymerization of Chloroprene Latex with Methyl Methacrylate by Emulsion Polymerization

Grafting of methyl methacrylate (MMA) onto chloroprene latex was carried out by emulsion polymerization.FTIR and 1H NMR confirmed that the grafted polymer was formed.Effects of the reaction temperature,the emulsifier concentration,the initiator concentration and the monomer concentration on the apparent polymerization rates were investigated.The results showed that the monomer conversion and the grafting efficiency could reach 99.1%,54.9%,respectively,under the conditions where the reaction temperature was 50 ℃,the dosage of initiator tert-butyl hydroperoxide/tetraethylenepentamine(t-BHP/TEPA) was 0.5% (based on the mass of dry chlorene rubber latex(CRL)),mass ratio of monomer to polymer was 3:5,and the amount of emulsifier sodium dodecylbenzenesulfonate(DSB) was 1% (based on the mass of monomer).The kinetics equation Rp=Kc(E) 0.15c(I) 0.30c(MMA) 1.41,where K is a constant,was obtained.The overall activation energy for the polymerization process was 60.2 kJ/mol within 40 ～ 55 ℃.The graftcopolymerization reaction follows the free radical mechanism generally.

Kinetic investigations of graft copolymerization of sodium styrene sulfonate onto electron beam irradiated poly(vinylidene fluoride) films

Graft copolymerization of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films was investigated to find out a simple preparation process for sulfonic acid proton exchange membranes with respect to monomer concentration, absorbed dose, temperature, film thickness and storage time. The reaction order of the monomer concentration and absorbed dose of grafting was found to be 2.84 and 1.20, respectively. The overall activation energy for graft copolymerization reaction was calculated to be 11.36 kJ/mol. The initial rate of grafting was found to decrease with an increase in the film thickness. The trapped radicals in the irradiated PVDF films remained effective in initiating the reaction without considerable loss in grafting level up to 180 days, when stored under −60 °C. The presence and distribution of polystyrene sulfonate grafts in the obtained membranes were observed by Fourier transform infrared (FTIR) spectroscopic analysis, scanning optical microscope and scanning transmission electron microscopy (STEM) coupled with X-ray energy dispersive (EDX), respectively.

Synthesis and characterization of fluorescent graft fluorene-co-polyphenol derivatives: The effect of substituent on solubility, thermal stability, conductivity, optical and electrochemical properties

A series of fluorene Schiff bases and their oligophenol derivatives were successfully synthesized using the condensation and graft copolymerization reactions, respectively. The synthesized compounds were good soluble in common organic solvents. Photoluminescence (PL) properties of the synthesized materials were determined in solution forms. As to the fluorene copolymers (FPs), higher PL intensities were obtained when compared with the monomeric models. Solvent effects on the fluorescence spectra and possible usages in spectrofluorometric ion sensors of the FPs were discussed. Optical and electrochemical band gaps of the polymers were lower than those of the Schiff bases indicating the more conjugated structures of the FPs. The oxidized states of the novel fluorene compounds were also examined by cyclic voltammetry (CV) technique. The solid state conductivity measurements showed that the synthesized FPs were semiconductors and when exposed to the iodine vapour their conductivities could be increased up to four orders of magnitude. The polymer having the lower band gap (FP-3) had also the highest undoped conductivity. Thermal characterizations of the synthesized compounds were carried out by TG-DTA and DSC methods. The initial degradation temperatures of the FPs were found quite high in the range of 220–300 °C.

Adsorptive removal of thorium(IV) from aqueous solutions using poly(methacrylic acid)-grafted chitosan/bentonite composite matrix: Process design and equilibrium studies

A novel composite matrix, poly(methacrylic acid) -grafted composite/bentonite (PMAA-g-CTS/B) was prepared through graft copolymerization reaction of methacrylic acid and chitosan in the presence of bentonite and N,N′-methylenebisacrylamide as cross linker. The composite was well characterized using FTIR, XRD, XPS, SEM, TG/DTG, surface area analyzer and zeta potential measurements. The adsorption behavior of the composite towards thorium(IV) from water and sea water was studied under varying operating conditions of pH, concentration of Th(IV), contact time, and temperature. The effective range of pH for the removal of Th(IV) was 5.0–6.0. Kinetic data followed a pseudo-second-order model. The equilibrium data were correlated with the Langmuir isotherm model. The equilibrium Th(IV) sorption capacity was estimated to be 110.5 mg/g at 30 °C. For the quantitative removal of 100 mg/L Th(IV) from 1.0 L simulated sea water, a minimum adsorbent dosage of 2.0 g PMAA-g-CTS/B was required. Adsorption–desorption experiments over four cycles illustrate the feasibility of the repeated uses of this composite for the extraction of Th(IV) from aqueous solutions. Counter current process design was done by using operational lines.

Vanadium(V)/mandelic acid initiated graft copolymerization of acrylamide onto guar gum in an aqueous medium

AbstractThe graft copolymerization reaction of acrylamide onto guar gum with a vanadium(V)/mandelic acid redox pair was carried out in an N2 atmosphere. The optimum concentrations of vanadium(V), mandelic acid, hydrogen ions, acrylamide, and guar gum for the maximum percentage of grafting were 6.0 × 10−3, 2.0 × 10−2, 55.0 × 10−2, and 20.0 × 10−2 mol/dm3 and 110.1 × 10−2 g/dm3, respectively. The optimum time and temperature of reaction were 90 min and 35°C, respectively, and during the study of [H+] variation, a prompt change in the value of the grafting parameters was observed. The maximum percentage of swelling of the graft copolymer was achieved at room temperature in 1 h. Studies of the flocculation, viscosity, and metal‐ion absorption capacity were also performed. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analyses, which showed that the grafted guar gum was thermally more stable than the ungrafted guar gum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Preparation and characterization of poly(acrylic acid)/pillared clay superabsorbent composite

Pillared clay-based superabsorbents (PILC-SA) were synthesized by using Al pillared-montmorillonite K10 and KSF via graft copolymerization reaction of acrylic acid (AA). Swelling behavior of pillared clay-based superabsorbent films in distilled water and at different pH values were investigated at room temperature. It was also obtained that Al-KSF and Al-K10 based superabsorbents were pH dependent and showed a reversible swelling behavior. Water absorbency of Al-KSF based superabsorbent was higher than that of Al-K10 based one. SEM, FTIR, and XRD analysis were conducted for further characterization of the PILC-SA. FTIR analyses lead to ester formation between PILC and SA. XRD revealed the basal spacing of the pillared clays before and after in situ incorporation indicating that the morphology of the superabsorbent was exfoliated and the layers of clay dispersed on the composite.