Grafting vinyl monomers onto silk fibers. X. Graft copolymerization of methyl methacrylate onto silk using hydrogen peroxide–thiourea redox system

The graft copolymerization of methyl methacrylate onto silk fibers initiated by a hydrogen peroxide–thiourea redox system was investigated under various conditions. The effects of monomer, initiator, temperature, acidity of the medium, and solvent on the rate of grafting were studied. The graft yield increases with the increase of monomer and initiator concentration. The graft yield also increases with the increase of acid concentration upto 22.50 × 10^?2M and thereafter it decreases. The effect of some inorganic salts on the rate of grafting has also been investigated, and a suitable mechanism has been suggested.     

Grafting vinyl monomers onto silk fibers IV. Graft copolymerization of methyl methacrylate onto silk using bromate-thiourea redox system

The use of a bromate-thiourea redox system to initiate graft copolymerization of methyl methacrylate onto silk has been investigated. The rate of grafting has been determined by varying the concentration of bromate ion, monomer, thiourea, the temperature and the solvent. The graft yield increases with increasing the bromate ion concentration up to 20 mmo1/1. With further increase of oxidant the graft yield decreases. The percentage of grafting increases with increase of hydrochloric acid up to 40 mmo1/1. Thereafter it decreases. The effect of increasing thiourea concentration up to 15 mmo1/1. is to bring about an increase in the graft yield. Above this concentration grafting decreases sharply. The rate of grafting increases with increase of temperature. The use of various water soluble solvents effects the percentage of grafting considerably. The alkali solubility of the grafted fiber has been investigated.     

Graft copolymerization of an itaconic acid/acrylamide monomer mixture onto poly(ethylene terephthalate) fibers with benzoyl peroxide

A mixture of acrylamide (AAm) and itaconic acid (IA) was grafted onto poly(ethylene terephthalate) (PET) fibers with benzoyl peroxide in aqueous media. The effects of polymerization conditions such as the temperature, polymerization time, initiator concentration, and monomer mixture ratio on grafting were investigated. The maximum graft yield was 76.1% with an AAm/IA mixture ratio of 90/10 (mol/mol). The graft yield was as low as 3% in the single grafting of IA, whereas the use of AAm as a comonomer increased the amount of IA that entered the fiber structure to 33.5%. An increase in the temperature from 65 to 85°C increased the grafting rate and saturation graft yield. However, an increase in the temperature above 85°C decreased the saturation graft yield. The graft yield increased up to an initiator concentration of 1.0 × 10^?2 M and decreased afterwards. The grafting rate was 0.65th‐ and 0.74th‐order with respect to the initiator and AAm concentrations, respectively. The densities, diameters, and moisture‐regain values of the AAm/IA‐grafted PET fibers increased with the graft yield. Similarly, there was an increase in the dyeability of the AAm/IA‐grafted fibers with acidic and basic dyes. The grafted fibers were characterized with Fourier transform infrared and thermogravimetric analysis, and their morphologies were examined with scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1795–1803, 2005     

Grafting vinyl monomers onto silk fibers,VII. Graft copolymerization of methyl methacrylate onto silk using peroxydiphosphate as initiator

Graft copolymerization of methyl methacrylate onto silk was investigated in aqueous solution using potassium peroxydiphosphate as initiator. The rate of grafting was determined by varying monomer, peroxydiphosphate ion, temperature, and solvent. The graft yield increased with increasing peroxydiphosphate ion upto 8 × 10^?3 mol/1 and with further increase of peroxydiphosphate ion the graft yield decreased. The graft yield increased with increasing monomer concentration upto 9 wt.-% and with further increase of monomer the graft yield decreased. The rate of grafting increased with the increase of temperature. The effect of acid and water soluble solvents and salts on graft yield was investigated and a suitable rate expression was derived.     

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.     

Grafting vinyl monomers onto silk fibers: Graft copolymerization of methyl methacrylate onto silk using acetylacetonate Mn(III) complex

The graft copolymerization of methyl methacrylate onto Mulberry silk fibers was studied in aqueous solution using Mn(acac)₃ as initiator. Perchloric acid was found to catalyze the reaction. The rate of grafting was investigated by varying the concentration of the monomer and the complex, acidity of the medium, the solvent composition of the reaction medium, the surfactants, and the inhibitors. The graft yield increases with increasing concentration of Mn(acac)₃ up to 0.01 mol/L, decreasing thereafter. Increase of MMA concentration up to 0.56 mol/L increases graft yield, and thereafter it decreases. Among the various vinyl monomers studied, MMA was found to be most suitable for grafting. Grafting increases up to 7.5 × 10^?3 mol/L of HClO₄ concentration, and thereafter it decreases. A suitable reaction scheme has been proposed and a rate equation has been derived. The energy of activation has been calculated from the Arrhenius plot. The chain transfer constants for various chain transfer solvents have been evaluated from the average molecular weight (M?) of grafted poly(methyl methacrylate).     

Grafting vinyl monomers onto silk fibers. VIII. Graft copolymerization of methyl methacrylate onto silk using tetravalent manganese–oxalic acid redox system

The graft copolymerization of methyl methacrylate onto silk fibers was investigated in aqueous solution using the Mn(IV)–oxalic acid redox system. The copolymerization reaction was carried out under a variety of conditions such as different monomer, initiator, oxalic acid, acid concentrations, and temperatures. The graft yield increases with increasing initiator concentration up to 5 × 10^?2M, and with further increase of the initiator concentration it decreases. The graft yield also increases with increasing sulfuric acid concentration up to 15 × 10^?2M, and decreases thereafter. The rate of grafting also increases with increase in oxalic acid concentration up to 1.5 × 10^?2M and 84.592 × 10^?2M, respectively, and thereafter the rate of grafting shows down. The effect of temperature, solvents, and salts on graft yield has also been investigated and a plausible rate expression has been derived.     

Grafting vinyl monomers onto wool fibers. VIII. Graft copolymerization of methyl methacrylate onto wool using peroxydiphosphate–fructose redox system

The graft copolymerization of methyl methacrylate onto wool fibers was investigated in aqueous solution using the peroxydiphosphate–fructose redox system. The rate of grafting was determined by varying monomer, acidity of the medium, temperature, nature of wool, and reaction medium. The graft yield increases with increase in peroxydiphosphate concentration. With increase in concentration of fructose up to 7.5 × 10^?4 mole/l., there is a significant increase in graft yield; and with further increase in concentration of fructose the graft yield decreases. The graft yield increases with increase in monomer concentration up to 65.72 × 10^?2 mole/l. and decreases thereafter. The grafting is considerably influenced by chemical modification prior to grafting. The effect of acid, temperature, and solvent on the rate of grafting has been investigated and a suitable rate expression has been derived.     

Grafting vinyl monomers onto silk fibers. II. Graft copolymerization of methyl methacrylate onto silk by hexavalent chromium ion

The feasibility of chromium(VI) to induce graft polymerization of methyl methacrylate onto silk was investigated. The rate of grafting was determined by varying monomer concentration, chromium(VI) concentration, temperature, acidity of the medium, nature of the silk, reaction medium, and redox system. The graft yield increased with increasing monomer concentration up to 0.65M, and with further increase of monomer the graft yield decreased. The graft yield increased with increasing chromium(VI) concentration. The grafting is considerably influenced by chemical modification of silk prior to grafting. The graft yield is influenced by thiourea concentration, decreasing with increasing thiourea concentration. The effect of certain inorganic salts and anionic surfactants on the rate of grafting was investigated.     

Grafting of poly(ethylene terephthalate) fibers with methacrylic acid using benzoyl peroxide

The graft copolymerization of methacrylic acid onto poly(ethylene terephthalate) fibers, by the aid of benzoyl peroxide, have been investigated. The graft yield increased up to 85°C, and then decreased with the further increase in temperature. The maximum graft yield was obtained at benzoyl peroxide concentration of 4.0 × 10^?3 mol/L. The increase in the concentration of monomer was found to increase the graft yield. The change in the graft yield was followed by the experiments carried out using different water/solvent mixtures. Also, the change in the properties of polye (thylene terephthalate) fibers grafted with methacrylic acid such as moisture regain, density, and diameter were investigated.     

Grafting vinyl monomers onto polyester fibers. VI. Graft copolymerization of methyl methacrylate onto PET fibers using tetravalent cerium as initiator

The graft copolymerization of methyl methacrylate onto polyester fibers (PET) was investigated using tetravalent cerium as the initiator. The rate of grafting was found to increase progressively with the initiator and monomer concentrations up to 2.5 × 10^?2M and 70.41 × 10^?2M, respectively. The reaction was found to be catalysed by acid up to 15.0 × 10^?2M. The graft yield increased by increasing temperature. The effect of addition of some solvents and thiourea on the rate of grafting was also investigated. A suitable kinetic scheme has been pictured, and rate equations have been derived.     

Graft copolymerization of 2‐acrylamido‐2‐methyl‐1‐propanesulphonic acid onto carboxymethylcellulose (sodium salt) using bromate/thiourea redox pair

Unreported graft copolymer of 2‐acrylamido‐2‐methyl‐1‐propanesulphonic acid (AMPS) with sodium carboxymethylcellulose (Na‐CMC) was synthesized and reaction conditions were optimized using a bromate/thiourea redox pair under an inert atmosphere at 40°C. Grafting ratio, add on, and conversion increase as the concentration of thiourea and [H⁺] increases up to 3.6 × 10^?3 and 0.6 × 10^?2 mol dm^?3, respectively, while on increasing the concentration of bromate ion and Na‐CMC, grafting ratio, add on, and conversion decrease. The samples of Na‐CMC and grafted Na‐CMC with AMPS were subjected to thermogravimetric analysis, with the objective of studying the effect of grafting of AMPS on the thermal stability of graft copolymer. The graft copolymer was found to be more thermally stable than pure Na‐CMC. Comparing the IR spectra of pure with grafted Na‐CMC confirm the evidence of grafting. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 100: 26–34, 2006     

Grafting of methyl methacrylate (MMA) onto Antheraea assama silk fiber

Graft copolymerization of methyl methacrylate (MMA) onto nonmulberry silk fiber Antheraea assama was investigated in aqueous medium using the KMnO₄–oxalic acid redox system. Grafting (%) was determined as a function of the reaction time, temperature, and monomer and initiator concentrations. The rate of grafting increased progressively with increase of the reaction time up to 4 h and then decreased. The extent of grafting was maximum at 55°C. The extent was also dependent upon monomer and initiator concentrations up to 75.5 × 10^?2 and 6 × 10^?3 M, respectively. The grafted products were evaluated by infrared spectroscopy and their thermal decompositions were studied by TG and DTG techniques in static air at 20°C min^?1 and 30°C min^?1 in the range 30–800°C. The kinetic parameters for ungrafted and grafted fibers were evaluated using the Coats and Redfern method. The grafted products were found to be thermally more stable than were those of the ungrafted fibers. The surface characteristics of the ungrafted and grafted fibers were evaluated by scanning electron microscopy. The water‐retention values (WRVs) of the grafted fibers were in decreasing order with increase in the grafting (%). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2633–2641, 2001     

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.     

Grafting vinyl monomers onto silk fibers III. Graft copolymerization of methyl methacrylate onto silk using tetravalent cerium as initiator

The use of tetravalent ceric ions to initiate graft-copolymerization of methyl methacrylate onto silk has been investigated. The rate of grafting has been determined by varying monomer, cerium (IV), temperature, and nature of silk. The graft yield increases with increasing monomer concentration up to 0.65 mol/l and with further increase of monomer, the graft yield decreases. The percentage of grafting increases with increasing ceric ion concentration up to 0.03 mol/l and thereafter it decreases. The rate of reaction is temperature dependent, with increasing temperature, the graft yield increases. The grafting is considerably influenced by chemical modification prior to grafting. The effect of different species of ceric ion and CuSO₄ on the rate of grafting has also been investigated.     

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.     

Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers using thallium(III) ions as initiator

Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers was investigated in aqueous perchloric acid medium using thallium(III) ions as initiator. The rate of grafting was evaluated varying the concentrations of monomer, initiator, and acid and the temperature. The rate of grafting was found to increase with increase in monomer and initiator concentrations. The graft yield was found to increase with increase in the acid concentration up to 0.49 mL^?1, and beyond this concentration it was found to decrease. Increase in temperature resulted in increase in graft yield. From the Arrhenius plot the overall activation energy was found to be 3.76 kcal/mol. The effect of additives such as swelling agents, inorganic salts, different solvents, and inhibitors on graft yield was studied. A suitable kinetic scheme is proposed and a rate equation derived.     

4-Vinylpyridine and 2-hydroxyethylmethacrylate monomer mixture graft copolymerization onto poly(ethylene terephthalate) fibers using benzoyl peroxide

Summary Poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of 4-VP/HEMA onto PET fibers. 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 maximum graft yield was obtained 280%. The optimum temperature and polymerization time was found to be 85 °C and 100 min. respectively. The rate of grafting was found to be proportional of the 1.5 and 0.3 powers of 4-VP/HEMA and Bz₂O₂ concentrations, respectively. The grafted PET fibers were characterized by thermo gravimetric analysis and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity, intrinsic viscosity and diameter were determined. The dye ability of the PET fibers increased with an increase in grafting with diazo and basic dyes.     

Grafting vinyl monomers onto wool fibers. I. Graft copolymerization of methyl methacrylate onto wool using V5+–thiourea redox system

The graft copolymerization of methyl methacrylate in wool fibers was investigated in aqueous solution using V⁵⁺—thiourea redox system. The rate of grafting was determined by varying monomer, thiourea, acidity of the medium, temperature, nature of wool, different acrylic monomers, and reaction medium. The graft yield increases significantly by increasing reaction time in the initial stages of the reaction but it does slow down on prolonging the duration of grafting. The effect of increasing monomer concentration brings about a significant enhancement in the graft yield. The graft yield increases with increasing thiourea concentration, but beyond 0.0075M, the percentage graft yield decreases. The graft yields are considerably influenced by chemical modification prior to grafting. Wool reduced with thioglycolic acid is more susceptible to grafting than untreated wool; the opposite effect is noted in the case of trinitrophenylated and esterified wools. A suitable kinetic scheme has been proposed and the rate equation has been evaluated.     

Kinetics of swelling assisted grafting of 4-vinyl pyridine onto poly(ethylene terephthalate) fibers using a benzoyl peroxide initiator

Summary Poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) using benzoyl peroxide (Bz₂O₂) as initiator. Fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of 4-VP onto PET fibers. Variations of graft yield with time, temperature, initiator and monomer concentrations were investigated. Percent grafting was enhanced significantly by increasing Bz₂O₂ concentration up to 2 × 1 0 ^-3 mol/L and then decreased upon further increase in initiator concentration. Increasing the 4-VP concentration up to 0.6 mol/L improves the graft yield significantly. The optimum temperature and polymerization time was found to be 50 °C and 2 h respectively. Further changes in properties of grafted PET fibers such as moisture absorption capacity and intrinsic viscosity were determined. Grafted PET fibers were charactarized by thermogravimetric analysis and scanning electron microscopy (SEM). Molar mass of the grafted chains was also determined.