Binary Vinyl Monomer Mixtures Research Articles

Sorption of Pb(II), Cu(II), Fe(II) and Cr(VI) metal ions onto cross-linked graft copolymers of chitosan with binary vinyl monomer mixtures

Novel adsorbents for sorption of Pb(II), Cu(II), Fe(II) and Cr(VI) metal ions from waste water were synthesized by simultaneous cross-linking and graft copolymerization of chitosan (Ch) with N-isopropyl acrylamide (NIPAM) and its binary comonomers acrylic acid, acrylamide and acrylonitrile in presence of azo-bis(isobutyronitrile) (AIBN) as free radical initiator and N,N′-methylene bisacrylamide (MBA) cross-linker. FTIR, XRD, SEM and TGA/DTA techniques were used to describe the structural aspects of cross-linked graft copolymers. The improvement in swelling properties of the synthesized hydrogels was utilized to explore their potential for sorption of toxic metal ions from aqueous solutions. Metal ion sorption by synthesized cross-linked adsorbents was studied as a function of the change in contact time, pH, temperature and concentration of metal ions from a solution of individual metal ions. Selective sorption of metal ions was performed by immersing polymeric samples in a solution containing four metal ions in the same concentration. Candidate polymers showed preferential sorption of metal ions in order of Cu(II)>Pb(II)>Fe(II)>Cr(VI) ions. Cross-Ch-g-poly(NIPAM-co-AAc), Cross-Ch-g-poly(NIPAM-co-AAm) and Cross-Ch-g-poly(NIPAM), showed best results for sorption of all ions from single and four component solutions.

Selective sorption of Fe(II) ions over Cu(II) and Cr(VI) ions by cross-linked graft copolymers of chitosan with acrylic acid and binary vinyl monomer mixtures

Low-cost and environment-friendly polymeric adsorbents for sorption of heavy metal ions were synthesized by simultaneous graft copolymerization and cross-linking of acrylic acid alone and with comonomers glycidyl methacrylate, acrylamide and acrylonitrile onto chitosan using free radical initiator and cross-linker in aqueous medium. Structural aspects of cross-linked graft copolymers have been characterized by FTIR, SEM, TGA/DTA, XRD and swelling behavior at pH 2.2, 7.0 and 9.4. An attempt has been made to study sorption of Cr(VI), Cu(II) and Fe(II) ions on cross-linked graft copolymers by equilibration method and to establish a relationship between structural aspects of graft copolymers and metal ion uptake efficiency and selectivity. Solutions of individual ions were used for non-competitive sorption onto synthesized bio-adsorbents as a function of change in contact time, temperature, pH and metal ion concentration in feed. Competitive sorption investigation was performed from an aqueous solution of ternary metal ions by batch equilibration at 25°C and at 7.0pH. Cross-linked graft copolymers showed better results than unmodified chitosan and showed preferential sorption of Fe(II) ions than Cu(II) and Cr(VI) ions.

Application of Sorghum Starch for Preparing Superabsorbent

Starch was extracted from Sorghum bicolor grains by alkali steeping method and was utilized for the production of absorbent material by grafting and crosslinking with binary mixtures of vinyl monomers viz. acrylic acid and acrylamide. Both unmodified and modified starches were characterized with Thermogravimetric analysis, Infra-Red spectroscopy, Scanning electron microscopy and X-ray diffraction analysis, to ascertain the modification of the starch. The parameters of the reaction system viz. initiator concentration, monomer concentration, starch to monomer ratio, etc. were optimized. The modified starch showed enhanced water absorption in the range of 49–85 g/g. Absorbency of the products increased after treatment with aqueous alkali solution due to saponification at higher temperature. The saponified products showed increased water absorption level in the range of 245–400 g/g. The product thus obtained using optimized condition of grafting, on saponification found to be highly superabsorbent displaying the water absorbency of 400 g/g. The influence of pH on absorption of water was also tested and best results were obtained at pH 7–8.

Synthesis and characterization of PET fibers grafted with binary mixture of 2-methylpropenoic acid and acrylonitrile by free radical: its application in removal of cationic dye

Grafting of binary vinyl monomer mixtures such as 2-methylpropenoic acid (MPA) and acrylonitrile (AN) onto poly (ethylene terephthalate) fibers (PET) was achieved in an aqueous medium with using benzoyl peroxide like free radical initiator. A new reactively fibrous adsorbent was used for removal of dye such as methylene blue (MB) from aqueous media through batch sorption method. Fibers adsorbent was swelled in solution to support the graft and the subsequent polymerization of MPA/AN onto polyester fibers. Optimum conditions for grafting were discovered and reactive fiber were characterized. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 8 × 10−3 mol/L. The percentage of grafting rose steadily with the vinyl monomer mixture monomer concentration (50 %). The optimum temperature and polymerization time were found to be 80 °C and 120 min, respectively. The use of AN and MPA monomers together in grafting produce a significant increased in the graft yield. Experimental studies showed that the percentage removal of MB was a great higher on the MPA/AN grafted PET (MPA/AN-g-PET) fibers than on the original PET fibers. The adsorbed quantity of MB improved with pH and basic pH was appropriate for the elimination of MB. MPA/AN-g-PET fibers removed 98 % of cationic dye when initial concentration diverse from 10 to 80 mg L−1 at pH 9.0. Almost all of the adsorbed cationic dye was eluted by ethanoic acid in methanol. Ten removal–desorption cycles indicated that the reactive fibers were favorable for repetitive use without notable change in removal capacity. Consequently, the MPA/AN-g-PET fibers have demonstrated potential as an effective adsorbent for the extremely effective removal of cationic dyes from aqueous media.

Microwave induced synthesis of graft copolymer of binary vinyl monomer mixtures onto delignified Grewia optiva fiber: application in dye removal.

Grafting method, through microwave radiation technique is very effective in terms of time consumption, cost effectiveness and environmental friendliness. Via this method, delignified Grewia optiva identified as a waste biomass, was graft copolymerized with methylmethacrylate (MMA) as an principal monomer in a binary mixture of ethyl methacrylate (EMA) and ethyl acrylate (EA) under microwave irradiation (MWR) using ascorbic acid/H2O2 as an initiator system. The concentration of the comonomer was optimized to maximize the graft yield with respect to the primary monomer. Maximum graft yield (86.32%) was found for dGo-poly(MMA-co-EA) binary mixture as compared to other synthesized copolymer. The experimental results inferred that the optimal concentrations for the comonomers to the optimized primary monomer was observed to be 3.19 mol/L × 10−1 for EMA and 2.76 mol/L × 10−1 for EA. Delignified and graft copolymerized fiber were subjected to evaluation of physicochemical properties such as swelling behavior and chemical resistance. The synthesized graft copolymers were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffraction techniques. Thermal stability of dGo-poly(MMA-co-EA) was found to be more as compared to the delignified Grewia optiva fiber and other graft copolymers. Although the grafting technique was found to decrease percentage crystallinity and crystallinity index among the graft copolymers but there was significant increase in their acid/base and thermal resistance properties. The grafted samples have been explored for the adsorption of hazardous methylene dye from aqueous system.

Surface Modification Of Ramie Fibers Using Microwave Assisted Graft Copolymerization Followed By Brevibacillus Parabrevis Pretreatment

Ramie fibers usually display poor interfacial adhesion when reinforced in hydrophobic polymer matrices. Hydrophilic nature of natural fibers becomes the most crucial issue in composites engineering. Surface modification of natural fibers has been found to be very effective in improving the fiber-matrix adhesion. In the present paper, we have reported the microwave assisted grafting of binary vinyl monomer mixtures on to ramie fibers (Boehmeria nivea) and bacterial cellulase assisted pre-treatment of ramie fibers using bacteria Brevibacillus parabrevis. The effects of these pretreatments on some properties of ramie fibers are discussed in the present paper. The modified fibers were characterized by scanning electron microscopy (SEM), X-ray diffraction, and TGA/DTA techniques to determine their morphology, crystallinity and thermal stability. Surface of ramie fiber becomes rough on grafting with synthetic polymers, whereas biologically modified ramie fibers showed the enhanced softness and smooth appearance due to the removal of gum materials and other impurities from the surface of fibers. Both the treatments have slightly changed the thermal stability and crystallinity of ramie fibers.

Development and assessment of the advanced graft copolymers obtained from Hibiscus sabdariffa biomass

AbstractIn this article, the morphological transformation in Hibiscus sabdariffa stem fiber through graft copolymerization with effective ethyl acrylate (EA) and its binary vinyl monomeric mixtures using ceric ammonium nitrate—nitric acid initiator system has been reported. Different reaction parameters such as temperature, time, initiator concentration, monomer concentration, and pH were optimized to obtain the maximum graft yield (117.3%). The optimized reaction parameters were then used to screen the additive effect of EA with n‐butyl acrylate (BA), acrylic acid (AA), and 4‐vinyl pyridine (4‐VP) in binary vinyl monomer mixtures on percentage grafting, properties, and the behavior of the fiber. The graft copolymers were characterized by FTIR, SEM, XRD, TGA, and DTA techniques and evaluated for physico‐chemical changes. With increase in the Pg a significant physico‐chemico‐thermal resistance, miscibility in organic solvents, hydrophobicity were found to increase, whereas crystallinity, crystallinity index, dye‐uptake, and hydrophylicity decreased, however, the cellulose form I remained unchanged. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Microwave‐enhanced synthesis of graft copolymer of binary vinyl monomer mixtures onto acetylated Saccharum spontaneum L and characterization

AbstractSynthesis of graft copolymer under the influence of microwave radiation is a rapid, efficient, clean, cheap, convenient, energy‐saving, and green method. Grafting of methylmethacrylate (MMA) + acrylamide (AAm), MMA + acrylonitrile (AN), and MMA + acrylic acid (AA) binary mixtures onto acetylated Saccharum spontaneum L was carried out under the influence of microwave radiation (MWR), and maximum graft yield 94.5% was found with MMA + AAm binary mixture. Synthesized graft copolymers were characterized with FT‐IR, scanning electron microscopy, TGA/DTA/DTG, and X‐ray diffraction techniques. Thermal stability of Ss‐g‐poly(MMA + AAm) was found to be more than that of acetylated S. spontaneum fiber and other graft copolymers. Although on grafting, percentage crystallinity and crystallinity index decreased but graft copolymers were found to exhibit more moisture, chemical, and thermal resistance. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 30: 122–137, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20209

Synthesis of graft copolymers of binary vinyl monomer mixtures onto acetylated Saccharum spontaneum L and characterization

AbstractMethylmethacrylate (MMA) + acrylamide (AAm), MMA + acrylonitrile (AN), and MMA + acrylic acid (AA) binary vinyl monomer mixtures were graft copolymerization onto acetylated Saccharum spontaneum L, was carried out and maximum graft yield (185.6 %) was found with MMA+AAm binary mixture. Synthesized graft co‐polymers were characterized with FT‐IR spectrophotometry, scanning electron microscopy (SEM), thermal analysis TGA/DTA/DTG, and X‐ray diffraction (XRD) techniques. Thermal stability of Ss‐g‐poly(MMA + AAm) was found to be more than that of natural, acetylated S. spontaneum fiber and other graft copolymers. Although on grafting, percentage crystallinity and crystallinity index were found to decrease but graft copolymers were found to exhibit more moisture, chemical, and thermal resistance. Also, it can be observed that the surface of the grafted fibers is highly rough in comparison with the ungrafted fiber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Induction of Morphological Changes in Hibiscus sabdariffa Fiber on Graft Copolymerization with Binary Vinyl Monomer Mixtures

Various reaction parameters of the graft copolymerization of Hibiscus sabdariffa fiber with methyl acrylate as principal monomer and its binary mixture with acrylonitrile, acrylic acid, and acrylamide were optimized. The graft copolymers obtained were characterized by XRD, TGA-DTA, SEM, and FT-IR techniques and were evaluated for different physicochemical changes like moisture absorption and chemical resistance against 1 N NaOH and 1 N HCl. The percentage crystallinity and crystallinity index were found to decrease with increase in grafting, while there was reduction in moisture absorption and increase in chemical and thermal resistance of the graft copolymers.

A Study of Crystallinity of Graft Copolymers of Flax Fiber with Binary Vinyl Monomers

AbstractThe present paper deals with graft copolymerization of binary vinyl monomer mixtures onto flax fiber. Maximum grafting (86.02 %) has been found with MMA+EA binary mixture. Percentage crystallinity and crystallinity index of graft copolymers were measured with X-ray diffraction (XRD) technique. Crystallinity of flax decreases on grafting with binary vinyl monomer mixtures. Flax showed the highest value of percentage crystallinity (76.96 %) and crystallinity index (0.7005) in comparison to Flax-g-copolymers.

Synthesis and Characterization of Graft Co-Polymers of Flax Fiber with Binary Vinyl Monomers

Grafting of flax fiber with binary vinyl monomer mixtures such as methylmethacrylate (MMA)/ethyl acrylate (EA), MMA/acrylonitrile (AN), and MMA/acrylic acid (AA) was carried out. At a pressure of 8 Kg/cm2 under optimum reaction conditions 41.74% grafting resulted. Maximum grafting (109.9%) was found with MMA + EA binary monomer mixture. Synthesized graft co-polymers were characterized with FT-IR spectroscopy, scanning electron microscopy (SEM), TGA/DTA techniques, and X-ray diffraction (XRD). Thermal stability of flax-g-poly(MMA/AA) was found to more than that of flax fiber and other graft co-polymers. On grafting, percentage crystallinity decreases rapidly with reduction in its stiffness and hardness. Flax fiber showed the highest value of percentage crystallinity (76.96 %) and crystallinity index (0.7005) in comparison to flax-g-co-polymers.

Free-radical copolymerization of binary mixtures of vinyl monomers of various compositions: Initiation rate constants

For a number of vinyl monomers (styrene, butyl acrylate, vinyl acetate, and methyl-, butyl-, and lauryl methacrylates) and their mixtures with a divinyl (network-forming) monomer—triethylene glycol dimethacrylate—with the molar ratio of binary mixture components varying from 0 to 100%, initiation rate constants have been measured through the inhibition method with the use of 2,2,6,6-tetramethyl-1-piperidinyloxy as a counter of free radicals. Viscosities at various temperatures and activation energies for the viscous flow of the monomers under study have been estimated. The relationship between the initiation rate constants and the viscosity of the medium has been established. On the basis of this relationship, the mechanism for the exit of radicals from the cage has been interpreted within the framework of the Franck-Rabinowitch model with allowance made for effects associated with formation of intermolecular associates in the systems under study.

Selective properties of polyester and cotton/polyester fabrics gamma radiation grafted with different binary mixtures of vinyl monomers

Radiation graft copolymerization of individual and comonomer mixtures of vinyl monomers onto polyester and cotton/polyester fabrics by the mutual method has been investigated. The effect of factors that may affect the grafting yield, such as solvent composition, comonomer mixture composition and radiation dose, have been examined. Suitable conditions that gives the highest graft yield without altering the original properties of the substrates are reported briefly. An attempt was made to determine the graft yield fraction from each monomer in the final graft copolymer in the case of grafting comonomer mixtures by using elemental analysis of nitrogen. Moreover, the results of elemental analysis were used to determine the reactivity ratios of the vinyl monomers. Some selective properties of the graft copolymers of polyester and cotton/polyester with the individual and comonomer mixtures have been investigated. The studied properties are the dye affinity for various dyestuffs and the mechanical properties in terms of tensile strength, elongation at break and Young's modulus. In general and regardless of the system used, grafting improves the dyeability of polyester and cotton/polyester with basic, vat, acid and disperse dyes. Also, it was found that improvement in dyeing and mechanical properties depends essentially on the composition of the graft copolymer and not on the composition of the feed comonomer solution or the total graft yield. © 1999 Society of Chemical Industry

Investigation of synergism during radiation graft copolymerization of binary mixtures of vinyl monomers onto different textile fabrics by a dyeing method

Radiation-induced graft copolymerization of binary mixtures of acrylic acid (AAc) and styrene (S) onto cotton, cotton/polyester’ and viscose rayon has been investigated. The different factors that may affect the total graft yield (the sum of polyacrylic acid (PAAc) fraction and polystyrene (PS) fraction, such as solvent composition, comonomer mixture, and irradiation dose were studied. It was found that there is always a certain solvent composition of (MeOH and H2O) and comonomer mixture at which a maximum value of total graft yield (TGY) was obtained. Moreover, the TGY was greatly influenced by other factors such as radiation dosage. An attempt was made to investigate synergism during graft copolymerization, i.e. the effect of each monomer on the other and their participation in the resulting graft copolymer. In this respect, the PAAc and PS graft fractions in the resulting graft copolymers of the different textile fabrics under investigation were determined approximately by dyeing with basic dye (Sandocryl Blue) and disperse dye (Samaron Blue FBL). By this method, it was possible to determine each fraction in the graft copolymer. It was also observed that the graft copolymerization increased the dye affinity for such dyestuffs to a great extent. The accuracy and validity of the dyeing method applied was supported by the estimation of the carboxyl group content by analytical technique based on acid–base volumetric titration. ©1997 SCI

Grafting onto polyester fibers. IV. Synergism during graft copolymerization of binary mixtures of vinyl monomers onto polyester fibers

AbstractGraft‐copolymerization reactions of binary mixtures of vinyl monomers (acrylamide–acrylic acid and acrylonitrile–acrylic acid) with polyester fibers have been studied by chemical initiation technique using benzoyl peroxide as an initiator. The total graft add‐on was determined gravimetrically, while the modified Kjeldahl's method for N‐estimation was employed to determine acrylamide and acrylonitrile grafts in their mixtures with acrylic acid grafts. Synergism of very high order was noticed during the graft‐copolymerization reactions. In the case of the acrylamide–acrylic acid system a very high order of synergism (129.15%) was noticed at equimolar proportions of the monomers in the grafting bath. Both acrylamide and acrylic acid showed synergistic influence over each other during graft‐copolymerization reactions. In the case of the acrylonitrile–acrylic acid system, however, the presence of acrylonitrile reduced the graft yield of the acrylic acid component showing a negative synergism; but acrylic acid enhanced the acrylonitrile graft yield to a considerable extent. The results have been explained in terms of reactivity ratios of the monomers. The conductivity results of the monomer mixtures also supported the experimental results.

Long‐lived polymer radicals. IV. Reactions of poly(N‐methylacrylamide) and poly(N‐methylmethacrylamide) radicals with binary mixtures of vinyl monomers

AbstractN‐methylacrylamide (NMAAm) and N‐methylmethacrylamide (NMMAm) were polymerized to give polymer microspheres containing living propagating radicals. The microsphere polymer radicals were allowed to react with some binary mixtures of vinyl monomers including alternating copolymerization combinations. The reaction processes were investigated by ESR spectroscopy. In the poly(NMMAm) radical/methyl methacrylate (MMA)/styrene (St) system, the propagating radical from MMA was mainly observed at the higher MMA concentration, while polySt radical prevailed at the lower MMA concentration. In the poly(NMMAm) radical/α‐methylstyrene (α‐MeSt)/diethyl fumarate system, the α‐MeSt radical was exclusively observed, while the maleic anhydride (MAn) radical was predominantly observed in the α‐MeSt/MAn system. In the MAn/diphenylethylene system, the propagating radicals from both monomers were observed at comparable concentrations. The poly(NMAAm) microsphere radical behaved differently in the reaction with the MMA/St mixture. The poly(NMAAm) microsphere was found to incorporate preferentially St, leading to formation of the St radical. The St preference was enhanced in the St/cyclohexyl methacrylate (CHMA) system. These results were in agreement with those of block copolymerization via the reaction of poly(NMAAm) radical with the MMA/St or CHMA/St mixture, where the compositions of the resulting polymers were analyzed by pyrolysis gas chromatography.