Potassium permanganate/thioureadioxide redox system-induced grafting of methacrylic acid onto loomstate cotton fabric

Graft polymerization of methacrylic acid (MAA) to loomstate cotton fabric using the KMnO₄/thioureadioxide system as the initiator was studied under different polymerization conditions. The polymerization reaction was assessed with respect to graft yield, homopolymer, total conversion, and graft efficiency. The magnitude of each of these characteristics was found to depend upon parameters such as concentrations of KMnO₄, thioureadioxide, and MAA as well as liquor ratio, reaction time, and temperature of polymerization. Based on a detailed investigation of these parameters, the optimal condition for grafting is KMnO₄ 0.045 g/L, thioureadioxide 0.03 g/L, material to liquor ratio 1 : 30, MAA 100% (owf), temperature 80°C, and time 60 min. A reaction mechanism for the polymerization reaction is also reported. © 1995 John Wiley & Sons, Inc.     

Graft polymerization of acrylic acid onto starch using potassium permanganate acid (redox system)

Graft polymerization of acrylic acid (AA) onto rice starch using postassium permanganate/acid redox system as initiator was investigated. When starch was reacted with KMnO₄ solution, MnO₂ was deposited onto starch. The dependence of MnO₂ amount deposited was directly related to KMnO₄ concentration. Subjecting the MnO₂-containing starch to a solution consisting of monomer (AA) and acid (citric, tartaric, oxalic and hydrochloric acid) formed poly(AA)–starch graft copolymers. The graft yield, expressed as meq COOH/100 g starch, was measured by the amount of MnO₂ deposited, AA concentration, material-to-liquor ratio, kind and concentration of acid, as well as temperature and duration. Finally, the newly prepared poly(AA)–starch graft copolymers were applied to cotton textiles to determine their suitability as sizing agents. The highest graft yield was obtained with citric acid and the least with hydrochloric acid, with tartaric and oxalic acid in between. The graft yield increased by increasing the concentration of acid to a certain concentration beyond which grafting leveled off. A similar trend was observed when the magnitude of grafting was related to the amount of MnO₂ deposited. The graft yield increased by increasing the polymerization temperature from 30° to 50°C. Increasing the temperature to 60°C is accompanied by decreased grafting. On the other hand, fabric samples sized with poly(AA)–starch graft copolymers acquire higher tensile strength, elongation at break, and abrasion resistance than that sized with native rice starch, i.e., poly(AA)–starch graft copolymers serve as good sizing agents for cotton textiles. A tentative mechanism for grafting rice starch with AA using the KMnO₄/acid redox system was elucidated. © 1995 John Wiley & Sons, Inc.     

Peroxydiphosphate–metal ion–cellulose thiocarbonate redox system‐induced graft copolymerization of vinyl monomers onto cotton fabric

The grafting of methacrylic acid (MAA) and other vinyl monomers onto cotton cellulose in fabric form was investigated in an aqueous medium with a potassium peroxydiphosphate–metal ion–cellulose thiocarbonate redox initiation system. The graft copolymerization reaction was influenced by peroxydiphosphate (PP) concentration, the pH of the reaction medium, monomer concentration, the duration and temperature of polymerization, the nature of vinyl monomers, and the nature and concentration of metallic ions (activators). On the basis of a detailed investigation of these factors, the optimal conditions for the grafting of MAA onto cotton fabric with the said redox system were as follows: [Fe²⁺] = 0.1 mmol/L, [PP] = 2 mmol/L, [MAA] = 4%, pH‐2, grafting time = 2 h, grafting temperature = 70°C, and material/liquor ratio = 1 : 50. Under these optimal conditions, the graft yields of different monomers were in the following sequence: MAA ? acrylonitrile > acrylic acid > methyl acrylate > methyl methacrylate. The unmodified cellulosic fabric (the control) had no ability to be grafted with MAA with the PP–Fe²⁺ redox system. The percentage of grafting onto the thiocarbonated cellulosic fabric was more greatly enhanced in the presence of iron salts than in their absence. This held true when the lowest concentrations of these salts were used separately. A suitable mechanism for the grafting processes is suggested, in accordance with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1879–1889, 2003     

Modification of carbohydrate polymers via grafting of methacrylonitrile onto pregelled starch using potassium monopersulfate/Fe2+ redox pair

The graft copolymerization of reactive pregelled starch (PGS) with methacrylonitrile (MAN) was performed and the reaction conditions were optimized using potassium monopersulfate (PMPS) in the presence of ferrous ion redox pair as initiator. Emphasis was directed towards increasing the graft formation and decreasing homopolymerization. The grafting parameters were studied with respect to graft yield and graft reaction efficiency percent. In addition, the newly prepared polymethacrylonitrile (polyMAN)‐pregelled starch graft copolymers were applied to cotton textiles to see their suitability as a new sizing agent. Based on the results obtained, appropriate conditions for grafting MAN onto pregelled starch was established and the graft yield was higher under the following conditions: using 0.004 mol l^?1 potassium monopersulfate as initiator, 0.005 mol l^?1 ferrous ion concentration, 0.003 mol l^?1, sulfuric acid, 50 % MAN concentration (based on weight of substrate), material to liquor ratio 1:2.5, reaction time 60 min, and polymerization temperature 40 °C. Finally, fabric samples sized with polyMAN‐pregelled starch graft copolymers acquired higher tensile strength and abrasion resistance than that sized with original pregelled starch, while elongation at break was unaltered. Copyright © 2004 Society of Chemical Industry     

Improved synthesis of poly(MAA)–starch graft copolymers

Graft copolymerization of methacrylic acid (MAA) onto starch using a potassium persulfate/sodium thiosulfate redox initiation system was investigated. Emphasis was placed on the promotion of graft formation while minimizing homopolymerization. This could be achieved through a thorough investigation into the major factors affecting the polymerization reaction such as the state of the starch, redox ratio of the initiator, monomer and initiator concentrations, time and temperature of polymerization, and material-to-liquor ratio. The results obtained imply that the magnitude of the polymer yield including total conversion, graft yield, and homopolymer are determined by these factors. The yield is favored under the influence of higher temperature, longer time, short liquor, and increased monomer and initiator concentrations. A poly-(MAA)–starch graft copolymer is the main product of the polymerization reactions only when starch was preswelled (through cooking prior to grafting). Moreover, this grafted product could be precipitated by more dilution with water and easily separated by filtration. Hence, the results of the current work formed the basis of a novel method for the synthesis of poly(MAA)–starch graft copolymers. The mechanisms involved in the synthesis are reported. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1709–1715, 1998     

Grafting of acrylic acid onto flax fibers using Mn(IV)‐citric acid redox system

When the flax fibers (machine tow) were treated with KMnO₄ solution, MnO₂ was deposited over‐all the fiber surface. The amount of MnO₂ deposited relied on the KMnO₄ concentration. Subjecting the flax‐containing MnO₂ to a solution consisting of monomer (acrylic acid, AA) and citric acid, CA (or any acid used in this work) resulted in formation of poly(AA)‐flax graft copolymer. Dependence of the polymer criteria, namely, the total percentage conversion (%TC) and the carboxyl content of the grafted flax fibers on various grafting parameters, viz., concentrations of the redox pair as well as AA, material‐to‐liquor ratio (M/R), duration and temperature of polymerization, kind of the acid and kind of the flax fibers pretreatment was studied systematically. The results indicated that the polymerizability of AA molecules, expressed as %TC (i.e., counting both grafting and homopolymerization) and thence the carboxyl content (i.e., evaluating the extent of AA grafting along the flax backbone) was optimized with the following conditions: [AA], 100% (based on weight of flax fibers, owf); [CA], 0.4 meq/1 g flax; [MnO₂], 0.4 meq/1 g flax; polymerization temperature, 40°C; polymerization time, 30 min; and the M/R, 1 : 50. A tentative mechanism for grafting of flax fibers with AA using MnO₂‐acid redox system was elucidated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3028–3036, 2006     

Synthesis and Flocculation Characteristics of Konjac Glucomannan-g-Polyacrylamide

A flocculant was synthesized by graft copolymerization of acrylamide onto konjac glucommannan using potassium permanganate/thiourea redox system as an initiator. The effects of the concentration of monomer, initiator, H₂SO₄, as well as reaction time and temperature on the graft copolymerization were studied. The optimum synthesis conditions were: the concentrations of acrylamide, KMnO₄ and H₂SO₄ were 2.0 mol.L^-1, 20 mmol.L^-1and 3.0 mmol.L^-1, respectively, and the molar ratio of KMnO₄/thiourea was 2/1 at 60 °C for 3 h. Compared with polyacrylamide, the graft copolymer had better flocculating effect on the kaolin suspensions, as well as the local Qinjiang river water and the machine water in paper making.     

Synthesis and characterization of cellulose ion exchangers. I. Polymerization of glycidyl methacrylate,dimethylaminoethyl methacrylate,and acrylic acid with cotton cellulose using thiocarbonate-H2O2 redox system

Polymerization of glycidyl methacrylate (GMA), dimethylaminoethyl methacrylate (DMAEMA) and acrylic acid (AA) with cotton fabric using a cellulose thiocarbonate-hydrogen peroxide redox system as an initiator was investigated under different conditions. This includes the nature and concentration of the initiator and monomer, polymerization time and temperature, and liquor ratio. The percent of polymer add-on is generally favored by increasing monomer and H₂O₂ concentration, as well as duration and temperature of the polymerization, but with the certainty that the percent of polymer add-on follows the following order: GMA > DMAEMA > AA. On the other hand, the percent of polymer add-on increases by decreasing the liquor ratio. Incorporation of Fe²⁺ or Cu²⁺ ion in the polymerization system enhances the percent of polymer add-on significantly. Replacing the H₂O₂ by other oxidants such as Cr⁶⁺ or Mn⁴⁺ is made, and the capability of such cations to expedite polymerization of the said monomers with cotton cellulose is studied. Also studied is the synthesis of cation exchanger via reaction of poly(GMA)-cellulose copolymer with hexamethylene tetramine. Furthermore, the ion exchange characteristics of the cellulosic copolymers obtained with this as well as with other monomers are reported. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1029–1037, 1997     

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.     

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.     

Amidoximated Sunflower Stalks (ASFS) as a New Adsorbent for Removal of Cu (II) from Aqueous Solution

A sunflower stalk graft copolymer was prepared by the reaction of ground sunflower stalks (SFS) with acrylonitrile (AN) in aqueous solution initiated by KMnO₄-citric acid (CA) system. It has been shown that the grafting parameters, such as concentration of KMnO₄, AN, and CA, have a significant effect on graft copolymerization. The temperature as well as the duration time of the reaction were studied and also showed a significant effect on the graft copolymerization reaction. The possible reaction was deduced by estimation of nitrogen content. Amidoximation of the grafted stalks was performed by the reaction of grafted SFS with hydroxylamine hydrochloride in alkaline medium to obtain amidoximated sunflower stalks (ASFS). The obtained amidoximated product was detected by FT-IR spectra. The effects of pH and concentration of the adsorbent, ASFS, on adsorption of Cu (II) were studied. The study shows that the ASFS was effectively used in adsorption of Cu (II) ions from aqueous solution. The adsorption data obeyed Langmuir and Freundlich isotherms.     

Preparation of high PMMA grafted particle SiO2 using surface initiated free radical polymerization

In this work, a convenient surface-initiated free radical graft-polymerization method, by which polymethacrylic acid (PMAA) with a high grafting density was grafted on silica gel particles, was put forward, and it was feasible and effective. The coupling agent γ-aminopropyltrimethoxysilane (AMPS) was first bound onto the surfaces of silica gel particles, obtaining the modified particles AMPS-SiO₂. So a redox initiation system was constituted with the amino groups on the surfaces of AMPS-SiO₂ particles and ammonium persulphate in the solution. A great deal of primary free radicals on the surfaces of AMPS-SiO₂ particles is produced via the redox initiating reaction, so that the surface-initiated free radical graft- polymerization of methacrylic acid (MAA) on the silica gel particles was realized, giving the grafted particles PMAA/SiO₂ with a high grafting degree (about 30 g/100 g) of PMAA. The effects of the main factors on the surface initiated graft polymerization were examined and the corresponding mechanism was investigated in depth. The experimental results show that for this surface-initiated free radical graft-polymerization of MAA, the suitable temperature is 40 °C. If the temperature is over 40 °C, the graft polymerization will be affected negatively, and the grafting degree of PMAA will decline because of the intense heat decomposition of ammonium persulphate. During the graft polymerization, the grafted polymer layer that has formed is a hindrance to the subsequent graft polymerization. The used amount of initiator and the monomer concentration affect the graft polymerization greatly. The appropriate reaction conditions are as follows: reaction time of 10 h, initiator persulphate amount of 1.1% (it implies the mass percent of the monomer), and monomer MAA concentration of about 5% (it drives at the mass percent of the solution).     

Grafting of N-methylolacrylamide onto flax/polyester fabric using ferrous cellulose thiocarbonate/H2O2 redox system

Graft copolymerization of N-methylolacrylamide onto flax/polyester blend fabric using ferrous cellulose thiocarbonate/H₂O₂ redox system was investigated under different conditions including hydrogen peroxide concentration (1?60 mmol/l), ferrous ammonium sulphate concentration (1?50 mmol/l), N-methylolacrylamide concentration (5?200%, based on weight of sample), polymerization time (10?90 min), temperature (20?50°C), and pH of the medium (1.1?11). The nitrogen content and/or the methylol content were used for calculation of graft yields. Results obtained indicated that graft yields, derived from nitrogen analysis, are higher the greater the H₂O₂ concentration increases till 40 mmol/l, then level off. On the other hand, graft yields derived from methylol content exhibit maximum value at 10 mmol/l H₂O₂. The results indicate also that grafting was highly favoured when it was carried out using 1 mmol/l ferrous ammonium sulphate and pH 4.4 at 30°C for 60 min. The apparent activation energy of the copolymerization reaction amounts to 9.74 kJ/mol. Furthermore, the graft yield increases by increasing N-methylolacrylamide concentration within the range studied. The work was further extended to include a comparison between the polymerization efficiencies of the ferrous cellulose thiocarbonate/H₂O₂ redox system and the ferrous/H₂O₂ redox system in inducing grafting of N-methylolacrylamide onto flax/polyester blend fabric. For this reason, the two systems were studied with respect to graft yield, homopolymer proportion, total conversion, graft efficiency, and homopolymer efficiency.     

Polymerization of glycidyl methacrylate,methacrylic acid,acrylamide and their mixtures with cotton fabric using fe2+-thioureadioxide-H2O2 redox system

Polymerization of glycidyl methacrylate (GMA), methacrylic acid (MAA), acrylamide (Aam) and their binary mixtures with cotton cellulose fabrics using Fe²⁺-thioureadioxide-H₂O₂ redox system was investigated under a variety of conditions. While temperatures of 50, 80, 65, and 95°C constituted the optimal polymerization temperature for GMA, MAA, Aam and GMA/MAA (8:2), respectively, maximum polymerization of GMA/MAA (2:8), Aam/MAA (8:2) and Aam/MAA (2:8) occurred at 75°C. The polymerization reaction proceeded initially very fast then levelled off irrespective of the monomer or monomer mixtures used. However, the magnitude of the polymer add-on at levelling off of polymerization followed the order GMA > GMA/MAA (2:8) ≥ GMA/MAA (8:2) > Aam/MAA (2:8) ≥ MAA ≥ Aam/MAA (8:2) > Aam. The polymer add-on enhanced by increasing the H₂O₂ concentration up to a certain limit and then decreased. The same situation was encountered with respect to thioureadioxide concentration. The involvement of the epoxy ring of GMA with MAA during polymerization of their mixture with cellulose occurred only at a higher ratio of GMA in the mixture. Also a significant contribution of Aam in the polymer add-on obtained with a Aam/MAA mixture could only be achieved at a higher ratio of Aam in this mixture.     

Graft polymerization of methyl methacrylate onto wool using dimethylaniline/copper(II) system

Dimethylaniline (DMA)/Cu^II-induced grafting of methyl methacrylate (MMA) onto wool fibres was studied under different conditions. The grafting reaction was found to be influenced by Cu^II, DMA, and MMA concentrations as well as polymerization temperature, reaction time, and polymerization medium. While the graft yield increased by increasing the amount of MMA from 100 to 500 mmol/L, maximum grafting occurred at 0.5 mmol/L CuSO₄, 10 mmol/L DMA. The graft yield increased by increasing the reaction time from 15 to 150 min and by raising the polymerization temperature from 60 to 80°C. Using dimethylformamide/water and ethyl alcohol/water mixture as a medium for grafting decreased the graft yield, while using isopropyl alcohol/water mixtures increased the graft yield as compared to pure aqueous medium.     

Graft copolymerization of methyl methacrylate and other vinyl monomers onto cotton fabric using ferrous cellulose thiocarbonate–N-bromosuccinimide redox initiation system

The cellulose thiocarbonate, in the fabric from, was treated first with a freshly prepared ferrous ammonium sulphate (FAS) solution. The sotreated fabric formed, with N-bromosuccinimide (NBS), an effective redox system capable of initiating grafting of methyl methacrylate (MMA) and other vinyl monomers onto the cotton fabric. The effect of the polymerization conditions the polymer criteria, namely, graft yeild, homopolymer, total conversion, and grafting efficiency, was studied. These polymer criteria were found to depend extensively upon concentrations of the Fe²⁺ ion (activator), NBS (initiator), and MMA; pH of the polymerization medium, and duration and temperature of polymerization. Based on detailed investigation of these factors, the optimal conditions for grafting were as follows: Fe²⁺, 1 × 10⁻³ mol/L; NBS, 1 × 10⁻² mol/L; MMA, 4%; pH, 2: polymerization time, 150 min; polymerization temperature, 60°C; material/liquor ratio, 1: 100. Under these optimal conditions, the rates of grafting of different vinyl monomers were in the following sequence: methyl methacrylate ≫ methyl acrylate > acrylonitrile. Other vinyl monomers namely, acrylic acid, and methacrylic acid have no ability to be grafted to the cellulosic fabric using the said redox system. A tentative mechanism for the polymerization reaction is suggested. © 1996 John Wiley & Sons, Inc.     

Effect of graft copolymerization of 2-hydroxyethyl methacrylate on the properties of polyester fibers and fabric

Graft copolymerization of hydroxyethyl methacrylate (HEMA) onto poly(ethylene terephthalate) (PET) fibers using benzoyl peroxide (BP) as initiator was carried out in water and in water/organic solvent as a reaction medium. The effect of initiator concentration, reaction time, temperature, and reaction medium as well as addition of FeSO₄ to the polymerization medium was studied. Percent grafting was enhanced significantly by increasing BP concentration up to 0.016 mol/L and then decreased upon further increase in initiator concentration. Increasing the monomer (HEMA) concentration up to 0.48 mol/L improves significantly the graft yield. Raising the polymerization temperature up to 85°C causes a significant increase in grafting yield; further increase in temperature leads to decrease in graft yield. Incorporation of Fe⁺² ions in the polymerization system decrease the graft yield. The same situation is encountered when water/solvent mixture is used as reaction medium. Solvent employed were methanol, toluene, and benzene.     

Graft copolymerization of acrylonitrile onto cotton cellulose by potassium permanganate–thioacetamide redox system

The graft copolymerization of acrylonitrile onto cotton, initiated by the KMnO₄–thioacet-amide redox system in an aqueous medium, has been investigated. The percentage graft yield was determined by varying the concentrations of KMnO₄, acrylonitrile, thioacetamide, and temperature. The percentage graft yield increased initially and then decreased with increasing concentrations of KMnO₄ and thioacetamide, with an optimum yield not greater than 21%. The percentage graft yield, however, was greatly enhanced with a value of up to 66% as the concentration of acrylonitrile was increased. The percentage graft yield increased with temperature in the range of 35–70°C with a calculated activation energy of 8.33 Kcal/mol. The effects of solvents and amines on the percentage graft yield were also investigated. © 1994 John Wiley & Sons, Inc.     

Chemical grafting of 2‐ethyl methacrylate phosphoric acid onto nylon 6 fabric

Graft copolymerization of 2‐ethyl methacrylate phosphoric acid (EMPA) onto nylon 6 fabric is carried out using the K₂S₂O₈/CuSO₄ system as reaction initiators. The most important factors affecting the graft yield are monomer concentration, reaction time and temperature. It was found that the graft yield increased with increasing EMPA concentration, grafting time, and temperature. The grafted nylon 6 fabric shows an increase in moisture regain to reach a maximum of 8.01% with increasing the graft yield to 35.6%. Also, the dyeability with the basic dye was significantly increased due to grafting with EMPA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1357–1361, 2000     

Silk grafting with methacrylamide: A near‐infrared spectroscopy study

The grafting of methacrylamide (MAA) onto silk has taken importance not only as weighting process but also as finishing operation to improve the properties of the silk fibers. It was confirmed that the MAA monomer concentration, the initiator amount, and the liquor ratio are the major parameters affecting the yield of the reaction. Varying these parameters, a large number of samples, i.e., silk yarns with different grafting yields and exhaust grafting baths with different residual MAA concentrations, were obtained. Near infrared (NIR) spectroscopy was used for the quantitative determination of MAA in silk yarns and MAA in exhaust baths after grafting. A correlation between silk yarns grafting yield and NIR spectra of MAA grafted yarns was obtained. This correlation shows a coefficient of determination (R²) of 0.96 and a standard error of calibration (SEC) of 8.37 w/w for a mean value (M) of 31.82% w/w. A second correlation between MAA in exhaust grafting baths and NIR spectra was obtained. This correlation shows a R² of 0.95 and a SEC of 2.93 g/L for a M of 17.16 g/L. Previous correlations were improved using silk samples cleaned by extraction of sizing agents and detergents which could interfere with MAA grafting and modify absorption spectra of bath solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011