Vanadium-cyclohexanone–initiated graft copolymerization of methyl methacrylate onto jute fibers

Graft copolymerization of methyl methacrylate (MMA) was carried out on jute fibers using a V⁵⁺ -cyclohexanone redox initiator system. The effect of the concentration of acid, monomer, and V⁵⁺ on graft yield have been studied. In order to obtain optimum conditions of grafting, the effects of temperature, acid, reaction medium, solvent, and some inorganic salts on graft yield have been investigated. The most remarkable features of the investigation include the proposition of a mechanism and derivation of rate expression for the grafting process. More than 100% grafting could be achieved with the present system.     

Graft copolymerization of acrylonitrile onto acetylated jute fibers

Graft copolymerization of acrylonitrile (AN) onto acetylated chemically modified jute was carried out in the temperature range 40–60°C using V⁵⁺-cyclohexanone redox initiator system. The effects of temperature, time, concentrations of metal ion (V⁵⁺), monomer (AN), cyclohexanone, some inorganic salts, and organic solvents on percent grafting have been studied. IR spectra of acetylated chemically modified jute and grafted jute have been taken, and their characteristic bands have been identified. Grafting has improved the thermal stability and also the lightfastness rating of jute fibers dyed with basic dyes.     

A study on graft copolymerization of methyl methacrylate onto jute fiber

A kinetic study of the graft copolymerization of methyl methacrylate onto jute fiber using KMnO₄–malonic acid redox initiator system has been made. Effects of the concentrations of malonic acid, monomer, and KMnO₄ on graft yield have been studied. Besides, the effects of temperature, acid, and reaction medium, some inorganic salts on graft yield have been investigated. The most remarkable features of the investigation include the proposition of a mechanism, derivation of rate expression for the grafting process, and characterization of the grafted fiber by thermogravimetric analysis.     

Chemically induced graft copolymerization of acrylonitrile onto lignocellulosic fibers

The grafting of vinyl monomers is an important method for replacing hydrophilic hydroxyl groups present on the surface of natural fibers by hydrophobic polymer chains. It improves the compatibility of natural fibers with polymer matrixes during the fabrication of natural‐fiber‐reinforced polymer composites. This article deals with the graft copolymerization of acrylonitrile onto Agave americana fibers in air in the presence of ceric ammonium nitrate as a redox initiator. A maximum percentage grafting of 24% was obtained after the optimization of various reaction parameters, including the reaction time, temperature, and concentrations of nitric acid, initiator, and monomer. The graft copolymers obtained under the optimum conditions were then subjected to the evaluation of different physicochemical properties, including swelling behavior in different solvents, moisture absorption behavior under different humidity levels, and chemical resistance. The graft copolymers were further characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermal analysis (thermogravimetric analysis/differential thermal analysis), and X‐ray diffraction techniques. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of glycine on the kinetics of the graft copolymerization of acrylonitrile onto jute fibers initiated by ceric ion

A study of the influence of glycine on the graft copolymerization of acrylonitrile (AN) onto jute fiber using ceric ion has been made. The effect of concentrations of monomer, Ce (IV), and glycine on graft yield have been studied. In addition, the effect of time, temperature, acid, and the amount of jute fiber on graft yield has been investigated. On the basis of experimental findings, a qualitative reaction mechanism has been proposed and the optimum condition for effective grafting has been suggested.     

Chemically induced graft copolymerization of vinyl monomers onto cotton fibers

We investigated the chemically induced graft copolymerizations of acrylic acid (AA), acrylamide, crotonic acid, and itaconic acid (IA) onto cotton fibers. Benzoyl peroxide was used as an initiator. The effects of grafting temperature, grafting time, and monomer and initiator concentrations on the grafting yields were studied, and optimum grafting conditions were determined for the sample material. The maximum grafting yield value obtained was 23.8% for AA. Swelling tests, Fourier transform infrared spectroscopy, and scanning electron microscopy analyses of grafted and ungrafted fibers were also performed to characterize fiber properties. IA‐grafted fibers were measured as the most swollen fibers, with a swelling value of 510%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2343–2347, 2006     

Grafting of vinyl monomers onto silk fibers: Trivalent-manganese-initiated graft copolymerization of acrylamide onto silk fibers

Graft copolymerization of acrylamide (AM) onto silk fibers, using Mn(III)–sulphate as initiator, has been investigated, in aqueous sulphuric acid in the temperature range of 30–55°C. Grafting reaction has been studied by varying the concentration of monomer, Mn(III), sulphuric acid, temperature, and also with the modified silk. The graft yield increases significantly with increase of monomer concentrations to the extent of 0.85M, after which the rate falls. With increase in Mn(III) concentration and H⁺ ion concentration the graft yield increases, but after an optimum concentration a depression in the graft yield is noticed. The rate of the reaction is temperature-dependent; with increase of temperature the graft-on increases. Among the solvent composition studied a solvent/water mixture containing 10% of the solvent seems to constitute the most favorable medium for grafting, and a further increase of solvent composition decreases the graft yield. The effect of various additives such as transition metal salts, aromatic and heterocyclic amines on grafting reaction has been studied. A suitable mechanism for grafting has been proposed. Finally physical characterization such as thermal analysis (TGA) of the grafted samples has been carried out in order to ensure grafting and to study the change in the properties of the fibers.     

Ce(IV)-N-acetylglycine initiated graft copolymerization of acrylonitrile onto chemically modified pineapple leaf fibers

Graft copolymerization of acrylonitrile (AN) onto chemically modified pineapple leaf fiber (PALF) was studied using Ce(IV) and N-acetylglycine (NAG) combination as initiator in the temperature range 40–60°C. The effects of concentration of monomer, Ce(IV), and NAG on graft yield have been studied. Besides the effects of time, temperature, acid, amount of PALF, some inorganic salts and organic solvents on graft yield have been investigated. FTIR and scanning electron microscopy of PALF and grafted PALF have been studied. Grafting has improved the thermal stability of PALF. © 1996 John Wiley & Sons, Inc.     

Influence of N-acetylglycine on the kinetics of the ceric ion-initiated graft copolymerization of acrylonitrile and methyl methacrylate onto jute fibers

The influence of N-acetylglycine on the kinetics of graft copolymerization of acrylonitrile (AN) and methyl methacrylate (MMA) onto chemically modified jute fibers was studied in the temperature range 40–60°C. The optimum conditions for grafting have been determined by studying the effects of concentrations of monomers, Ce(IV), and N-acetylglycine on the rate of grafting. Besides the effect of time, temperature, and concentration of the acid, the amount of jute fibers and some organic solvents and inorganic salts on the rate of grafting has been investigated. On the basis of experimental findings, a kinetic scheme has been proposed. Infrared spectra of chemically modified jute and grafted jute have been investigated. More than 185% graft yield could be achieved with the present system. Grafting has improved the thermal stability of jute fibers. © 1994 John Wiley & Sons, Inc.     

Influence of dimethyl sulfoxide on the kinetics of the graft copolymerization of acrylonitrile onto the jute fibers initiated by ceric ion

A study of the influence of dimethyl sulfoxide (DMSO) on the graft copolymerization of acrylonitrile (AN) onto jute fiber using ceric ion has been made. The effect of concentrations of monomer, Ce(IV) and DMSO on graft yield have been studied. Besides, the effect of time, temperature, acid, and the amount of jute fiber on graft yield has been investigated. On the basis of experimental findings, a reaction mechanism has been proposed and optimum condition for effective grafting has been suggested.     

Trivalent manganese chelate-initiated graft copolymerization of methyl methacrylate onto silk fibers

The graft copolymerization of methyl methacrylate onto silk fibers was investigated in aqueous solution using Mn³⁺ acetyl acetonate [Mn(acac)₃] as initiator. The rate of grafting was determined by varying monomer, acidity of medium, temperature, and reaction medium. The graft yield increases significantly with increase of [Mn(acac)₃] concentration up to 0.01M, and with further increase of [Mn(acac)₃] the graft yield decreases. The effect of the increase of monomer concentration brings about a significant enhancement in the graft yield, and with further increase the graft yield decreases. The rate of reaction is temperature dependent; with increasing temperature, the graft yield increases. Among the solvent composition studied, a water/solvent mixture containing 10% of the solvent seems to constitute the most favorable medium for grafting, and, with further increase of solvent composition, the graft yield decreases. The effect of some inorganic salts, organic solvents, and complexing agents has been investigated.     

Studies on graft copolymerization of methyl methacrylate onto chemically modified tussa silk fibers. Peroxydisulfate-thiourea redox system

The graft copolymerization of methyl methacrylate (MMA) onto chemically modified tussa silk fibers in aqueous media using potassium peroxodisulfate-thiourea redox initiator system was studied at 60°C. The effects of time of reaction, concentrations of oxidant, thiourea (TU), monomer (M), amount of silk fibers on graft yield have been studied. The effects of reaction medium, acid concentration, and some inorganic salts and organic solvents on grafting have also been investigated. A significant increase in percent of grafting was observed with increasing monomer concentration to 65.86 · 10^?2 mol · 1^?1; a further increase of monomer concentration is associated with the decrease of graft yield. The graft yield increases with an increase of thiourea concentration up to 10 · 10^?1 mol · 1^?1, beyond which it decreases very significantly. A measurable increase of the graft yield was also observed with an increase of the oxidant concentration up to 0.08 mol · 1^?1 beyond which the graft yield decreased. The graft yield was medium dependent. The reaction mechanism of the grafting process has been proposed and a rate expression has been derived on the basis of experimental findings. IR spectra of the grafted fiber and original fiber have been taken and their characteristic bands have been identified. The thermal behaviour of the original and grafted silk fibers has been studied by TGA and DTG analysis. Grafting has improved thermal stability as well as the light fastness of silk dyed with Rhodamine B.     

Graft copolymerization of glycidylmethacrylate onto modified nylon‐6 fibers

The graft copolymerization of glycidylmethacrylate (GMA) onto modified nylon‐6 fibers containing polydiallyldimethylammonium chloride (PDADMAC) groups in the presence of (Cu ²⁺–K₂S₂O₈) as a redox initiating system was carried out, with very high extent and almost without homopolymer formation. The mechanism of the graft polymerization induced by this system was suggested. The rate of grafting was determined by varying the monomer, K₂S₂O₈, and cupric ion concentrations as well as the amount of PDADMAC. The kinetic investigation revealed that the rate of grafting (Rp) of GMA onto modified nylon‐6 fibers is proportional to [GMA]^1.83, [CuSO₄·5H₂O]^0.46, [PDADMAC]^0.4, and [K₂S₂O₈]^1.43. The overall activation energy was 134.7 kJ/mol. The fine structure and thermal properties of the grafted nylon‐6 fibers were investigated. investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 613–618, 2006     

Chemical modification of jute fibers. II: A study on the Fe2+/H2O2-initiated graft copolymerization of methyl methacrylate,acrylonitrile, and acrylamide onto jute fibers

The study of graft copolymerization of methyl methacrylate, acrylonitrile, and acrylamide onto both defatted and bleached jute fibers using the ferrous ammonium sulfate / H₂O₂ redox initiator system has been made. To determine the optimum conditions of grafting, the effects of concentrations of ferrous ammonium sulfate, monomer, H₂O₂; time and temperature on percentage of graft yield have been studied. Acrylamide was found to graft onto the fiber only at a fixed ferrous ammonium ion concentration (5 × 10^?4M). Kinetic studies showed that the rates of grafting follow the second-order mechanism. The activation energies of the reactions were found to be 3.351 and 2.53 kcal/mol in the methyl methacrylate and acrylonitrile systems, respectively. The grafted fibers have been characterized by thermogravimetric analysis, IR spectroscopy, and XRD studies.     

Redox-initiated vinyl graft copolymerization onto wool with thiourea as the reductant. III. Di-tert.-butyl peroxide thiourea system

Graft copolymerization of wool with methyl methacrylate (MMA) induced by di-tert.-butyl peroxide (DTBP)/thiourea (TU) system in acid medium was studied. The rate of the copolymerization reaction depends on concentrations of DTBP, TU and MMA, temperature as well as kind of acid and solvent used. The graft yield increases by increasing the concentration of DTBP and MMA. Increasing the temperature enhances also the graft formation; 60°C produces higher grafting than 50°C. Carrying out the graft polymerization reaction in acid medium by using nitric acid has proved to be the best in comparison with sulphuric and formic acid. There is an optimal concentration of TU (0.4 M); lower grafting is achieved below and above this concentration. A mixture of isopropanol/water at a ratio of 10:90 constitutes the most favourable reaction medium since increasing the solvent content is accompanied by a reduction in the graft yield. The kind of solvent does affect the graft yield: for the solvent studied, the graft yield follows the order: isopropanol < acetone < dimethylsulphoxide. Incorporation of an acid dye in the polymerization system to affect concurrent dyeing and grafting was carried out and the properties of the products so obtained were examined. The changes in alkali solubility of wool by grafting was also investigated. In addition, a reaction mechanism based essentially on complexes formed between DTBP and wool and/or DTBP and TU and their subsequent dissociation to give wool macroradicals was suggested.     

Radiation-induced graft copolymerization of methacrylic acid onto polypropylene fibers VI. Dyeing behavior

The dyeing behavior of polypropylene-g-polymethacrylic acid fibers prepared by graft copolymerization of methacrylic acid onto polypropylene fibers by gamma-ray irradiation was evaluated for their dyeability characteristics using two basic dyes, rhodamine B and methylene blue. An increase in the dye uptake and moisture regain with the increase in graft content was observed. Such behavior has been attributed to the hydrophilicity imparted to polypropylene fiber by the presence of polar carboxyl groups in polymethacrylic acid grafts. The dependence of rate of dyeing on the percentage graft was evaluated. The diffusion coefficient of the fiber showed an increase with the increase in graft content and has been related to the structural changes occurring during grafting.     

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

Graft-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.     

Radiation-induced graft copolymerization of methacrylic acid onto polypropylene fibers. III. Characterization

Polypropylene-g-polymethacrylic acid graft copolymer, prepared by simultaneous-irradiation technique, was characterized to determine the structural changes, occurring in the copolymer. The presence of polymethacrylic acid graft in the copolymer was ascertained by infrared spectroscopy. Crystallinity of the grafted fibers, as deduced from X-ray diffraction pattern, showed a decrease with the increase in graft level in the fiber. Such a behavior has been attributed to the dilution of crystalline fraction of polypropylene by the incorporation of amorphous polymethacrylic acid chains in the fiber matrix, without disrupting the original crystallites of the backbone polymer. The density of the grafted samples showed a continuous increase with the increase in percent graft. However, the diameter did not change up to 16% graft content, beyond which an increase in the diameter was observed. This increase in diameter has been related with the sharp increase in disperse dye uptake of the grafted fiber at higher levels of grafting.     

Radiation-Induced graft copolymerization of methacrylic acid onto polypropylene fibers. V. Mechanical properties

Mechanical properties of polypropylene-g-poly(methacrylic acid) fibers, prepared by graft copolymerization of methacrylic acid onto polypropylene fiber using simultaneous gamma ray irradiation technique, were evaluated. In general, an improvement in the mechanical behavior of the polypropylene fiber by grafting was observed. Denier and initial modulus of the fiber showed a linear increase with the percent graft, and elongation showed an opposite trend. The results have been explained in terms of reinforcing effect of poly(methacrylic acid) grafts and reduction in the segmental mobility of the polymeric chains. Tenacity also increases up to certain graft level, beyond which a sharp decrease occurs, probably due to the influence on the compactness of the macromolecular chains with the further grafting.     

Radiation-Induced graft copolymerization of methacrylic acid onto polypropylene fibers. IV. Thermal behavior

Thermal behavior of polypropylene-g-poly(methacrylic acid) fibers prepared by graft copolymerization of methacrylic acid onto polypropylene fibers, using simultaneous-irradiation technique, was evaluated by thermogravimetric analysis, differential scanning calorimetry, and limiting oxygen index measurements. In general, the thermal properties of polypropylene fiber were markedly improved by the grafting of methacrylic acid. The inherent crystallinity of polypropylene, as deduced from DSC, did not show any change in the grafted fibers, suggesting that the grafting occurs in the amorphous region, without disrupting the crystalline part of the polymer. The LOI of grafted fibers showed an increase over the original fiber.