Grafting onto wool. XVI. Graft copolymerization of vinyl monomers by use of TBHP–FAS as redox initiator

Methyl acrylate (MA), methyl methacrylate (MMA), and n-butyl vinyl ether (n-BVE) have been graft-copolymerized onto Himachali wool in an aqueous medium by using tertiary butyl hydroperoxide ferrous ammonium sulfate (TBHP-FAS) redox system at 40°C, 50°C, 60°C, and 70°C for various reaction periods. Percentage of grafting and percent efficiency have been determined as functions of concentration of monomers, molar ratios of [TBHP]/[FAS], time and temperture. Molar ratios of [TBHP]/[FAS] were found to influence grafting of different monomers studied. Chemical evidence indicates that a covalent bond formation occurs between grafted polymeric chain and backbone polymer. The rate of grafting (R_p) and induction period (I_p) of different monomers towards graft copolymerization were determined as function of total initial monomer concentrations. R_p and I_p of n-BVE are independent of total initial monomer concentrations while R_p and I_p of both MA and MMA were found to depend on the total initial monomer concentrations. MA, MMA, and n-BVE were found to differ in reactivity towards grafting onto wool in the presence of (TBHP-FAS) redox system; the following reactivity order was observed: MMA > MA > n-BVE.     

Grafting of methyl methacrylate onto guar gum by hydrogen peroxide initiation

Graft copolymerization of methyl methacrylate (MMA) onto guar gum (GG) in aqueous slurry has been carried out using hydrogen peroxide (H₂O₂) as initiator. The copolymers were characterized by infrared spectroscopy. The grafting parameters like percent grafting, grafting efficiency, percent add-on, and the grafting frequency were determined, and the effect of reaction time, concentration of initiator, and [GG]/[MMA] ratios on the grafting parameters have been discussed. The decrease in % add-on at increasing concentration of H₂O₂ indicated enhancement in the rate of homopolymerization of methyl methacrylate.     

Grafting onto wool. XXIII. Graft copolymerization of methyl methacrylate by use of chromium acetyl acetonate–perchloric acid system: Effect of tertiary butyl hydroperoxide

Methyl methacrylate (MMA) has been graft copolymerized onto Himachali wool in an aqueous medium by using chromium acetyl acetonate in the presence of perchloric acid at 45, 55, 65, and 75°C for various reaction periods. Percentage of grafting has been determined as functions of various reaction variables. Tertiary butyl hydroperoxide (TBHP) was found to influence grafting of MMA. Rate of grafting (R_p) and induction period (I_p) of MMA towards graft copolymerization were determined as function of total initial monomer concentrations. In the absence of TBHP, R_p does not change markedly with the increase in monomer concentration. When the graft copolymerization was carried out in the presence of TBHP, an increase in R_p and a decrease in I_p were observed.     

Grafting onto wool. XIV. Graft copolymerization of vinyl monomers by use of Mn(AcAc)3 as an initiator

Ethyl acrylate (EA), butyl acrylate (BA), and vinyl acetate (VAc) have been graft copolymerized onto Himachali wool fiber in an aqueous medium by using Mn(AcAc)₃ as an initiator. Graft copolymerization was studied at 45°, 55°, 65° and 75°C for various reaction periods. Percentage of grafting and percent efficiency were determined as functions of concentration of monomer, concentation of initiator, concentration of nitric acid, time, and temperature. Several grafting experiments were carried out in the presence of various additives which included: (i) pyridine and (ii) Et₃ N. EA, BA, and VAc were found to differ in reactivity towards grafting and followed the order: EA > BA > VAc.     

Graft polymerization of methyl methacrylate onto wool initiated by ferric acetylacetonate/dichloroacetic acid system

The graft polymerization of methyl methacrylate (MMA) initiated by ferric acetyl acetonate/dichloroacetic acid [Fe(acac)₃–Cl₂CHCOOH] system onto wool has been investigated in a mixture of water and dioxane. No grafting occurred in organic solvent; water was essential to the grafting. Both the total conversion and the percentage of grafting showed maxima when the mole ratio of Fe(acac)₃ and Cl₂CHCOOH was ¼. Increasing wool content increased the percentage of grafting, while homopolymer conversion was independent of wool content. The rate of grafting was not proportional to MMA concentration. The grafting mechanism was discussed from these results.     

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.     

Grafting onto wool. XXVIII. Effects of acids on gamma-radiation induced graft copolymerization of ethylmethacrylate onto wool fiber

Graft copolymerization of ethylmethacrylate (EMA) onto Himachali wool fiber has been investigated in aqueous medium by mutual gamma irradiation from a Co⁶⁰ source in air and in nitrogen atmosphere. Percentage of grafting has been evaluated as a function of (i) total dose, (ii) concentration of monomer, and (iii) effect of concentration of different acids such as hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, and acetic acid. Maximum percentage of grafting has been obtained in the presence of sulfuric acid. Following reactivity order of different acids towards grafting has been observed: H₂SO₄ > HCI > HNO₃ > HCIO₄ > CH₃COOH. A plausible mechanism to explain the effect of acids on percentage of grafting of EMA has been suggested.     

Synthesis of deoxy(thiosulfato)chitin as the precursor for noncatalytic photoinduced graft copolymerization

Photoinduced graft copolymerization of vinyl monomers onto deoxy(thiosulfato)chitin (S₂O₃–chitin) has been studied. Chitin was first tosylated and subsequently transformed into S₂O₃–chitin. S₂O₃–chitin has good solubility over tosyl–chitin. Graft copolymerization of S₂O₃–chitin proceeded very easily by ultraviolet irradiation without catalyst. Photolysis of S₂O₃ groups was confirmed by infrared spectra. But the photolysis occurred only in quartz, not in a Pyrex tube. Methyl methacrylate (MMA) and acrylonitrile showed good grafting activities. In the case of acrylic acid and acryl amide, homopolymer formation was predominant, and the degree of grafting was low. We chose the MMA monomer for further information. The grafting rate of S₂O₃–chitin using MMA was much faster than those of chitin and O‐acetyl–chitin. Under the appropriate conditions, the degree of grafting reached 600% only in 2 h, and the grafting efficiency was over 75% in any monomer concentration. But addition of DMSO into the polymerization system decreased the degree of grafting. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 189–195, 1999     

Synthesis and kinetics of ascorbic acid initiated graft copolymerized delignified cellulosic fiber

Graft copolymerization of delignified Grewia optiva fiber with methyl methacrylate (MMA) as vinyl monomer was attempted using ascorbic acid/H₂O₂ as redox initiator. Different reaction conditions affecting the grafting percentage (P_g) were optimized to get the maximum P_g (32.56%) of MMA onto delignified Grewia optiva fibers. Grafted and ungrafted fibers were subsequently subjected to evaluation of physico‐chemical properties such as swelling behavior and acid and alkali resistance. The rate expression for the grafting reaction (R_g = k [ASC]^0.12 [H₂O₂]^0.53 [MMA]^0.05) was evaluated and a suitable mechanism for grafting was suggested. The overall activation energy of the copolymerization reaction was found as 11.97 kJ mol^?1 at temperature range 25–65°C. Further, morphological and structural analysis of raw, delignified, and grafted Grewia optiva‐g‐poly(MMA) were studied by using Fourier‐transform Infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, and thermogravimetric analysis.The tensile properties of grafted and ungrafted fiber samples were also reported. POLYM. ENG. SCI., 55:474–484, 2015. © 2014 Society of Plastics Engineers     

Grafting onto wool,XVII. Graft copolymerization of methyl acrylate and ethyl acrylate by use of VO(acac)2 as initiator. Comparison of monomer reactivities

Graft copolymerization of acceptor monomers methyl acrylate and ethyl acrylate onto Himachali wool fiber has been studied in aqueous medium by using vanadium oxyacetyl acetonate as initiator at 40, 50, 60, and 70°C. Graft copolymerization was carried out for various reaction periods and nitric acid was found to catalyse the reaction. Percentage of grafting and percent efficiency have been determined as functions of concentration of nitric acid, concentration of initiator, concentration of monomer, time, and temperature. Under optimum conditions, methyl acrylate and ethyl acrylate afforded maximum grafting to the extent of 28.4 and 18.5%, respectively. Relative reactivities of methyl acrylate and ethyl acrylate towards grafting have been compared with those of methyl methacrylate, acrylic acid and vinyl acetate reported earlier from this laboratory. Different vinyl monomers showed the following reactivity order: MMA > MA > EA > AAc > VAc. Several grafting experiments were carried out in the presence of various additives which included tert-butylhydroperoxide (TBHP), dimethylsulfoxide, pyridine, and dimethylformamide. Only TBHP was found to enhance grafting to a considerable extent, other additives decrease percent grafting of both methyl acrylate and ethyl acrylate.     

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.     

Grafting vinyl monomers onto wool fibers: Graft copolymerization of methyl methacrylate onto wool fibers using vanadyl acetyl acetonate complex

The graft copolymerization of methyl methacrylate (MMA) onto native and reduced Indian Chokla wool fibers was studied in aqueous solution using the acetylacetonate oxovanadium (IV) complex. The rate of grafting was investigated by varying the concentration of the monomer and the complex, acidity of the medium, and the solvent composition of the reaction medium. The graft yield increases with increasing concentration of the initiator up to 8.75 × 10^?5 mol/L, of the monomer up to 0.5634 mol/L, and thereafter it decreases. MMA was found to be the most active monomer when compared to other vinyl monomers. Grafting increases with increasing concentration of HClO₄ and with increasing temperature. Reduced and oxidized wools were found to be better substrates than untreated, esterified, crosslinked, and trinitrophenylated wools. The extent of grafting was mostly dependent upon the concentration of ? SH groups in case of reduced wool. A suitable reaction scheme has been proposed and the activation energy was calculated from Arrhenius plot.     

RAFT polymerization of N‐vinyl pyrrolidone using prop‐2‐ynyl morpholine‐4‐carbodithioate as a new chain transfer agent

RAFT polymerization of N‐vinyl pyrrolidone (NVP) has been investigated in the presence of chain transfer agent (CTA), i.e., prop‐2‐ynyl morpholine‐4‐carbodithioate (PMDC). The influence of reaction parameters such as monomer concentration [NVP], molar ratio of [CTA]/[AIBN, i.e., 2,2′‐azobis (2‐methylpropionitrile)] and [NVP]/[CTA], and temperature have been studied with regard to time and conversion limit. This study evidences the parameters leading to an excellent control of molecular weight and molar mass dispersity. NVP has been polymerized by maintaining molar ratio [NVP]: [PMDC]: [AIBN] = 100 : 1 : 0.2. Kinetics of the reaction was strongly influenced by both temperature and [CTA]/[AIBN] ratio and to a lesser extent by monomer concentration. The activation energy (E_a = 31.02 kJ mol^?1) and enthalpy of activation (ΔH^?= 28.29 kJ mol^?1) was in a good agreement to each other. The negative entropy of activation (ΔS^? = ?210.16 J mol^‐1K^‐1) shows that the movement of reactants are highly restricted at transition state during polymerization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Graft copolymerization of methacrylates onto wool fibers

Grafting of butyl (BuMA), decyl (DeMA), and octadecyl methacrylate (ODeMA) onto reduced wool was carried out by using K₂S₂O₈ or K₂S₂O₈–LiBr redox system as initiator. The influence of the monomer and monomer concentration, temperature, and duration of the reaction on the percentage of grafting was studied. Evidence of grafting was provided by scanning electron microscopy, size exclusion chromatography, and infrared spectroscopy.     

Grafting onto wool. VII. Ceric ion-initiated graft copolymerization of vinyl monomers. Comparison of monomer reactivities

In an attempt to compare relative reactivities of vinyl monomers toward grafting, methyl methacrylate (MMA) and acrylic acid (AAc) were grafted separately to Himachali wool in aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Nitric acid was found to catalyze the reaction. Percent grafting was determined as a function of concentration of nitric acid, concentration of CAN, concentration of monomer, time, and temperature. Optimum conditions for maximum grafting were evaluated for each monomer and were found to depend upon the nature of the monomer. Reactivities of MMA and AAc toward grafting were compared with those of methyl acrylate (MA), ethyl acrylate (EA), and vinyl acetate (VAc) reported earlier from this laboratory and were found to follow the order MA > EA > MMA > VAc > AAc. An explanation for the observed order of reactivity of different vinyl monomers is presented.     

Radiation‐induced graft copolymerization of methylmethacrylate onto poly(tetrafluoroethylene‐co‐ethylene) film

Modification of poly(tetrafluoroethylene‐co‐ethylene), Tefzel (ETFE), film has been carried out by grafting methylmethacrylate (MMA) by radiation method including preirradiation and double‐irradiation methods. Percentage of grafting has been determined as a function of the (i) total dose, (ii) monomer concentration, (iii) amount of liquor ratio, (iv) reaction time, and (v) temperature.The effect of different alcohols such as methanol, ethanol, 2‐propanol, n‐butanol, n‐pentanol, and 2‐ethoxy ethanol on percentage of grafting of MMA was also studied. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis (TGA). Methylmethacrylate produces higher percentage of grafting by preirradiaton method than double‐irradiation method. MMA‐grafted ETFE films (S_irr), i.e., prepared by preirradiation involving single irradiation show better thermal stability than MMA‐grafted ETFE films (D_irr), i.e., prepared by double irradiation and unmodified ETFE film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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.     

Radiation‐induced graft polymerization of methyl methacrylate onto ultrahigh molecular weight polyethylene in the presence of a metallic salt and acid

An attempt was made to graft methyl methacrylate (MMA) onto ultrahigh molecular weight polyethylene preirradiated in air in the presence of a metallic salt and acid. The grafting yield increased with increasing monomer concentration. The maximum grafting yield was around a 60 vol % monomer concentration. The results showed that the inclusion of FeSO₄ · 7H₂O and sulfuric acid in MMA grafting solutions was extremely beneficial and led to a most unusual synergistic effect in the radiation grafting, much more than with only a metallic salt. However, CuSO₄ · 5H₂O led to a detrimental effect. It is believed that sulfuric acid accelerates the decomposition of hydroperoxides in the presence of metallic salts such as Fe²⁺, inhibiting homopolymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2348–2356, 2002     

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.     

Graft copolymerization of methyl methacrylate onto rubber‐wood fiber using H2O2 and Fe2+ as an initiator system

Methyl methacrylate (MMA) was successfully grafted onto rubber‐wood fiber in a free‐radical solution polymerization initiated by ferrous ion and hydrogen peroxide. The effects of the reaction parameters (reaction temperature, reaction period, influence of hydrogen peroxide, ferrous ammonium sulfate, and monomer concentrations) were investigated. The grafting percentage showed dependency on H₂O₂, Fe²⁺, and monomer concentrations, as well as reaction temperature and reaction period. The optimum reaction temperature was determined to be about 60°C and the reaction period was 60 min. The optimum concentration of H₂O₂ was 0.03M and optimum amounts of Fe²⁺ and MMA were 0.26 mmol and 2.36 × 10^?2 mol, respectively. Poly(methyl methacrylate) (PMMA) homopolymer was removed from the graft copolymer by Soxhlet extractor using acetone. The presence of PMMA on the fiber was shown by FT‐IR spectroscopy and gravimetric analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2499–2503, 2003