Free‐radical grafting of 4‐vinyl pyridine onto nylon 6 fiber

The chemistry of free‐radical graft copolymerization initiated with peroxomonosulfate (PMS)–thioglycolic acid (TGA) redox system has been investigated by using 4‐vinyl pyridine (4VP) as a model for nylon 6 fiber in aqueous solution under nitrogen atmosphere. Effects of concentration of 4VP, PMS, TGA, nylon 6, time, and temperature on R_h and graft parameters were studied. The FTIR spectrum of nylon 6‐g‐4VP was reported. Water retention capacity (WRC) of the grafted fiber was tested. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3108–3113, 2002     

Peroxomonosulphate initiated graft copolymerization of o‐toluidine onto nylon 6 and wool fibers—A kinetic approach

Chemical polymerization of o‐toluidine (OT) in the presence of nylon 6 and wool fibers initiated by peroxomonosulphate (PMS) in an aqueous acidic medium was carried out under nitrogen atmosphere. During the polymerization process, graft copolymers were formed along with homopolymers of OT. A procedure is given for the separation of poly(o‐toluidine) (POT) grafted fiber from the homopolymer. Rate of homopolymerization (R_h), rate of grafting (R_g), percentage grafting, and percentage grafting efficiency were determined. Rate constants were evaluated from the experimental results. The chemical grafting of POT onto nylon 6 and wool fibers was confirmed through Fourier transform infrared (FTIR) spectroscopy and electrical conductivity measurements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2317–2326, 2002     

Grafting of acrylonitrile onto styrene-maleic acid copolymer by tetravalent cerium ion

The graft copolymerization of acrylonitrile (AN) onto a styrene-maleic acid copolymer (SY-MAc) with ceric ammonium nitrate (CAN) as a redox initiator in an aqueous medium has been studied. The effects of various reaction parameters, including reaction time and temperature, concentrations of initiator, nitric acid, and monomer, on the grafting yields and the rates of polymerization (R_p), graft copolymerization (R_g), and homopolymerization (R_h) were studied systematically. The results are discussed. The kinetic scheme of free-radical graft copolymerization has been proposed and the equations relating the values of R_p, R_g, and R_h are also suggested. The experimental results are found to be in good agreement with the proposed kinetic scheme. The activation energies of graft copolymerization and total polymerization are calculated. © 1995 John Wiley & Sons, Inc.     

Peroxydisulfate initiated graft copolymerization of aniline onto poly(propylene) fiber—A kinetic approach

A novel method for the preparation of electrically conducting fibers through chemical grafting of electrically conducting polymer onto poly(propylene) (PP) fiber is described. The graft copolymerization of aniline (ANI) was performed in aqueous acidic medium by using a chemical oxidant such as peroxydisulfate (PDS). Grafting occurred with simultaneous homopolymer formation. The content of polyaniline in the backbone fiber was found to vary by varying [monomer], [initiator], and amount of PP fiber. Various graft parameters such as rate of grafting (R_g), % grafting, and % grafting efficiency were evaluated. The rate of homopolymerization (R_h) was also determined. Both R_h and R_g showed first‐order dependency on [ANI], [PDS], and amount of PP fiber variation. The chemical grafting was confirmed by use of cyclic voltammetry and conductivity measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3827–3834, 2003     

Grafting onto wool

Summary In order to ascertain the role of -SH groups in graft copolymerization of vinyl monomers onto Himachali wool fiber, an attempt has been made to graft copolymerize ethylacrylate (EA) onto reduced wool, in the presence of cerie sulfate (CS) as redox initiator in aqueous medium. Reduction of wool was carried out with thioglycolic acid (TGA) in aqueous solution. Percentage of grafting and percent efficiency were determined as functions of (a) Concentration of initiator (CS), (b) Concentration of monomer (EA), (c) Concentration of Sulfuric acid, (d) Time and (e) Temperature. Reduction of wool does not promote grafting of EA. The unreduced wool during ceric ion-initiated grafting of EA was reported earlier from this laboratory to produce more grafting. In ceric ion-initiated grafting of vinyl monomer onto wool, -SH groups do not play significant role. A plausible mechanism of grafting of EA onto reduced wool in the presence of ceric ion initiator has been suggested.     

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

In 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 P_g 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     

Grafting onto wool fibers: Graft copolymerization of methyl methacrylate onto wool fibers initiated by KHSO5/Fe(III) couple

Graft copolymerization of methyl methacrylate (MMA) onto wool fibers has been carried out in an aqueous medium under deaerated condition initiated by potassium monopersulphate (KHSO₅/Fe(III) system, at varying concentration of the reactants and temperature. The effect of various salts and organic solvents on the extent of grafting has also been studied. Maximum graft percentage of 210.8% was obtained in 4 h at 40°C with the concentration of MMA (0.46 M), KHSO₅ (0.0195 M), Fe(III) (1.25 × 10^?4 M) in the presence of 50% formic acid. Various improved properties of the grafts have been studied and compared with the parent fiber.     

Synthesis and blend morphology of BA/BC-type binary graft copolymers composed of polyelectrolyte trunks

Poly(α-methylstyrene) (PMS) macromonomer having one vinylbenzyl group per polymer chain was prepared by the couplings of living PMS with p-chloromethylstyrene (CMS). Subsequently, well-defined poly[acrylic acid (AA)-g-α-methylstyrene (MS)] and poly[4-vinylpyridine (4VP)-g-MS] graft copolymers composed of polyelectrolyte trunks were prepared by radical copolymerization of PMS macromonomer with AA and 4VP monomers, respectively. Binary poly(AA-g-MS)/poly(4VP-g-MS) or poly[AA · triethyl amine (Et₃N) salt-g-MS)/poly(4VP-g-MS) graft copolymer blend films were cast from a benzene/methanol mixture. The morphological results of binary graft copolymer blends are discussed with respect to three-phase separated structures.     

Grafting onto wool. XI. Graft copolymerization of poly(vinyl acetate) and poly(methyl acrylate) onto reduced wool in presence of potassium persulfate–ferrous ammonium sulfate (KPS—FAS) system as redox initiator

In an attempt to ascertain the role of—SH groups of Himachali wool during graft copolymerization, poly(viny acetate) (PVAc) and poly(methyl acrylate) (PMA) were graft copolymerized onto reduced wool by using potassium persulfate—ferrous ammonium sulfate (KPS—FAS) redox pair in aqueous medium. Reduction of wool was carried out by sodium bisulfite solution of varying concentrations for different reaction periods. Concentration of reducing agent and the extent of reduction were found to influence grafting of vinyl monomers. Maximum grafting of methyl acrylate (MA) and vinyl acetate (VAc) occurred when wool was reduced by 1% and 0.5% NaHSO₃ solution, respectively, for 24 h. Increase in percent grafting of MA onto reduced wool compared to that of unreduced wool has been ascribed to the production of more—SH groups by reduction of—SS—groups of wool fiber.     

Grafting onto wool

Summary In order to study the role of -SH group of wool in graft copolymerization, an attempt has been made to study grafting of acrylic acid (AAc) onto reduced wool in aqueous medium using ceric ammonium nitrate (CAN) as redox initiator. HNO₃ was found to catalyze the graft copolymerization. Reduction of wool was effected with thioglycolic acid (TGA) in aqueous medium. Percentage of grafting was determined as a function of concentration of (i) CAN, (ii) vinyl monomer (AAc), (iii) nitric acid, (iv) time and (v) temperature. Under optimum conditions, poly-(acrylic acid) was grafted to the reduced wool to the extent of 9.14%, the unreduced wool under optimum conditions afforded maximum grafting of poly(AAc) to the extent of 12.24%. Reduction of wool does not promote grafting of AAc in the presence of CAN.     

Characterization and thermal stability of cellulose‐graft‐polyacryloniytrile prepared by using KMnO4/citric acid redox system

An effective condition of graft polymerization of acrylonitrile onto cellulose fiber in large volume of KMnO₄/citric acid aqueous solution was examined and the produced grafted copolymers were characterized by using SEM, NMR, FTIR, XRD, TGA, and DSC in comparison with component homopolymers. Graft yield, GY, obtained by simple weighting method was close to the value obtained by NMR analysis. Significant change of chemical structure in cellulose fiber, other than graft reaction, was not detected by NMR and FTIR measurements, whereas a decrease in the degree of crystallinity by the reaction was detected by XRD measurement. It was pointed out that thermograms for grafted samples resembles with that of cellulose at T < 370°C and become similar with that for polyacrylonitrile at T > 370°C and the mass of residue at 550°C is proportional to the content of polyacrylonitrile (GY) only. It is concluded that thermal decomposition of both polymers occurs almost independently in grafted polymers and thermal stability of cellulose fiber is not improved. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study of thermal and dyeing behavior of isotactic polypropylene fiber graft copolymerized with acrylate monomers using preirradiation method

In an attempt to modify isotactic polypropylene (IPP) fiber, grafting of acrylate monomers such as methyl acrylate (MA) and ethyl acrylate (EA) onto IPP has been carried out by preirradiation method in aqueous medium. Percentage of grafting has been determined as a function of various reaction parameters. Rate of grafting (R_g) and induction period (I_p) have been evaluated as a function of total initial monomer concentration. Methyl acrylate was found to be more reactive than ethyl acrylate toward grafting. Thermogravimetric analysis (TGA) indicates that the thermal stability of polypropylene fiber is significantly improved upon grafting. While polypropylene fiber could not be dyed by crystal violet, the grafted fiber was dyed with crystal violet, and the dye uptake has been quantitatively determined by spectrometric method. © 1994 John Wiley & Sons, Inc.     

Chemical oxidative grafting of conducting poly(N‐methyl aniline) onto poly(ethylene terepthalate)

Detailed studies on the peroxidisulfate (PDS) initiated graft copolymerization of N‐methyl aniline (NMA) with poly(ethylene terepthalate) (PET) were carried out in p‐tolene sulfonic acid medium under nitrogen atmosphere. Experiments were designed to follow the rate of formation R_h of the poly(N‐methyl aniline (PNMA), simultaneously with the rate of grafting of PNMA onto PET. Effects of concentration of NMA, PDS, PET, time, and temperature on R_h and graft parameters were followed. Kinetic equations were deduced to correlate the changes in the rate with experimental conditions. Graft copolymers were isolated and grafting of PNMA onto PET was confirmed through FTIR, thermogravimetric analysis, and conductivity measurements. Tensile measurements showed that grafting of PNMA did not alter the tensile properties of PET. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 596–605, 2005     

Graft copolymerization of 4-vinyl pyridine onto isotactic polypropylene hydroperoxide by mutual irradiation method

An attempt has been made to graft copolymerize 4-vinyl pyridine onto isotactic polypropylene hydroperoxide by mutual irradiation method in an aqueous medium. Polypropylene hydroperoxide has been prepared by irradiating recrystallized polypropylene beads from a Co⁶⁰ source in the presence of air. The resulting polypropylene hydroperoxide beads have been used as the backbone polymer and grafting of 4-vinyl pyridine has been studied as a function of various reaction parameters. Optimum conditions for maximum percentage of grafting have been evaluated. Rate of grafting (R_g) has been determined as a function of preirradiation dose and initial monomer concentration. Water has been found to affect percentage of grafting. The graft copolymers have been characterized by spectroscopic method and isolation of the grafted poly(4-VP) from the graft copolymer. A plausible mechanism is proposed to explain the mutual grafting of 4-vinyl pyridine onto polypropylene hydroperoxide. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of mica—vinyl graft copolymers

Graft copolymerization of methyl methacrylate (MMA) and acrylonitrile (AN) onto mica was carried out by the ceric ion method. Experiments were carried out both in the presence and absence of oxygen; oxygen has some detrimental effect in the grafting of AN onto mica. Mica—vinyl graft copolymers were characterized using infrared spectra after purifying the crude graft copolymers for the removal of the occluded homopolymers. The percent grafting, grafting efficiency and the ratio of R_g/R_h were determined. Mica—graft copolymers were saponified by treating with aqueous alkali to convert the nitrile groups to carboxyl groups with a view to utilize these groups for coupling to collagen substrates. Since in a chrome-tanned leather there are available coordination sites due to fixed chromium, the mica—graft copolymer could get bound, thereby resulting in a well filled-up leather.     

Grafting vinyl monomers onto polyester fibers. III. Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) using potassium permanganate–oxalic acid redox system

The use of the KMnO₄—oxalic acid redox system to initiate graft copolymerization of methyl methacrylate (MMA) onto poly(ethylene terephthalate) (PET) fiber has been investigated. The rate of grafting was determined by varying the concentrations of monomer, KMnO₄, oxalic acid, acidity of the medium, and temperature. The graft yield increases steadily with increasing KMnO₄ concentration. The graft yield is also influenced with concentration. The graft yield is also influenced with temperature. The effect of certain solvents on the rate of grafting has been investigated, and a suitable reaction mechanism has been proposed.     

A study toward the physicochemical properties of graft copolymer (partially carboxymethylated guar gum‐g‐N,N′‐dimethylacrylamide): Synthesis and characterization

Unreported graft copolymer of N,N′‐dimethylacrylamide (DMA) with partially carboxymethylated guar gum (CmgOH) has been synthesized and the reaction conditions have been optimized for affording maximum grafting using a potassium peroxymonosulphate (PMS)/thiourea (TU) redox initiators under nitrogen atmosphere. The study of graft copolymerization has been performed to observe maximum value of grafting parameters except percentage of homopolymer by varying the concentrations of DMA, PMS, and TU. The grafting parameters increase continuously on increasing the concentration of DMA from 8 × 10^?2 to 24 × 10^?2 mol dm^?3, PMS from 5 × 10^?3 to 21 × 10^?3 mol dm^?3, and TU from 1.6 × 10^?3 to 4.8 × 10^?3 mol dm^?3. The optimum temperature and time for grafting of DMA onto CmgOH were found to be 35°C and 120 min, respectively. The water‐swelling capacity of graft copolymer is investigated. Flocculation property for both coking and noncoking coals is studied for the treatment of coal mine waste water. The graft copolymer is characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Chemical and mechanical properties of methyl methacrylate-grafted wool fiber

Since it has been reported in the literature that polymer-grafted wool fibers have better acid and alkali resistances and dye uptake, the present study was carried out using KBrO₃ and substrates such as Fe (II), Co (II), cysteine, cystine, tyrosine, and urea for graft copolymerization of methyl methacrylate (MMA) onto wool. Acid and alkali resistances, dye uptake, and dry tensile strength of the resulting graft copolymers were studied.     

Grafting onto wool. XX. Graft copolymerization of vinyl monomers by use of redox initiators. Comparison of monomer reactivities

Methyl methacrylate (MMA) and ethylacrylate (EA) have been graft copolymerized onto Himachali wool in aqueous medium by using a ferrous ammonium sulfate–hydrogen peroxide (FAS? H₂O₂) system as redox initiator. Percentage of grafting has been determined as functions of concentration of monomer, molar ratio of [FAS]/[H₂O₂], time and temperature. Percentage of grafting is found to depend upon the molar ratio of [FAS]/[H₂O₂]. An attempt has been made to compare the reactivities of the acceptor monomer (MMA and EA) with that of the donor monomer (VAc) toward grafting onto wool.     

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.