Grafting onto Wool. XXVI. Graft Copolymerization of Vinyl Monomers by Use of Cr(acac)3-TBHP as Initiator

Methyl methacrylate (MMA), methyl acrylate (MA), and ethyl acrylate (EA) have been graft copolymerized onto wool fiber in aqueous medium using the chromium acetylacetonate-tertiary-butyl hydroperoxide (Cr(acac)₃-TBHP) system as initiator. The percentage of grafting has been determined as a function of the concentrations of monomer, chelate, and TBHP, and the time and temperature under optimum conditions. MMA produced a maximum grafting of 119.8%, MA produced a maximum grafting of 56%, while EA afforded maximum grafting to the extent of 41.9%. Different vinyl monomers were found to follow the following reactivity order toward grafting onto wool fiber in the presence of the Cr(acac)₃-TBHP system: MMA > MA > EA.     

Grafting onto Wool. IX. Graft Copolymerization of Vinyl Monomers by Use of Vanadium Oxyacetylacetonate as Initiator

Methyl methacrylate (MMA), acrylic acid (AAc), and vinyl acetate (VAc) were graft copolymerized onto Himachali wool in an aqueous medium by using vanadium oxyacetyl acetonate as initiator. Graft copolymerization was studied at 45, 55, 65, and 75°C for various reaction periods. The percentage of grafting was determined as functions of concentration of monomers, concentration of initiator, time, and temperature. The maximum percentage of grafting with each monomer occurred at 55°. Several grafting experiments were carried out in the presence of various additives which include HNO3, DMSO, and pyridine. Nitric acid was found to promote grafting of MMA. All these additives had adverse effects on grafting of VAc and AAc. MMA, VAc, and AAc were found to differ in reactivity toward grafting and followed the order MMA > AAc > VAc.     

Grafting onto Wool. XXVII. Graft Copolymerization of MixeD Vinyl Monomers by Use of Ceric Ammonium Nitrate as Redox Initiator

In order to ascertain the effect of a donor monomer, vinyl acetate (VAc), on the graft copolymerization of acceptor monomers, ethyl acrylate (EA) and butyl acrylate (BA), grafting of mixed vinyl monomers (EA + VAc) and (BA + VAc) was carried out on Himachali wool in aqueous medium using ceric ammonium nitrate (CAN) as a redox initiator. Graft copolymerization was carried out at different temperatures for various reaction periods. Percent grafting and percent efficiency were determined as functions of 1) concentration of mixed vinyl monomers, 2) concentration of CAN, 3) concentration of HNO₃ 4) temperature, and 5) reaction time. VAc, the donor monomer, was found to decrease percent grafting of EA and BA onto wool.     

Grafting onto Starch. IV. Graft Copolymerization of Methyl Methacrylate by Use of AIBN as Radical Initiator

Grafting of poly(methyl methacrylate) onto starch has been investigated in aqueous medium by using AIBN as radical initiator. Starch-g-PMMA has been characterized by determination of starch in the graft copolymer. Percentage of grafting has been determined as functions of concentration of monomer, concentration of initiator, reaction time, and temperature. From scanning electron microscopic studies, evidence for grafting of PMMA onto starch has been presented.     

Grafting Vinyl Monomers onto Wool Fibers. X. Graft Copolymerization of Methyl Methacrylate onto Wool Using Acetylacetonato Complex of Manganese(lII)

The graft copolymerization of methyl methacrylate onto wool fibers was investigated in aqueous solution using the acetylacetonato complex of manganese(III). The rate of grafting was determined by varying the monomer, the complex, the temperature, the acidity of the medium, the nature of the wool, and the reaction medium. The graft yield increases with increasing monomer and complex concentrations. The graft yield also increases with increasing temperature. The grafting is considerably influenced by chemical modification of wool prior to grafting. A suitable mechanism has been proposed and a rate equation has been derived.     

Graft Copolymerization of Poly(ethyl Acrylate) onto Wool in the Presence of Ceric Ammonium Nitrate as Redox Initiator

Poly(ethyl acrylate) has been grafted onto Himachali wool in an aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Copolymerization was studied at five different temperatures: 40, 45, 50, 55, and 60°C. Maximum grafting occurred at 45°C. Nitric acid was found to catalyze the graft copolymerization reactions. Percentage and efficiency of grafting were found to be dependent upon concentrations of CAN (initiator) and of monomer. Percentage of grafting has been determined as function of time, and from the slope of percent grafting versus time plot, the initial rate of graft copolymerization (R) has been determined.     

Grafting Vinyl Monomers onto Wool Fibers. VII. Graft Copolymerization of Methyl Methacrylate onto Wool Using Peroxydiphosphate-Thiourea Redox System

Graft copolymerization of methyl methacrylate onto wool was investigated in aqueous solution using the potassium peroxy-diphosphate-thiourea redox system as the initiator. The rate of grafting was determined by varying the monomer, peroxydi-phosphate ion, temperature, and solvent. The graft yield increases with increasing peroxydiphosphate ion up to 80 × 10^?-⁴ mol/L, and with further increase of peroxydiphosphate ion the graft yield decreases. The graft yield increases with increasing monomer concentration. The percentage of grafting decreases with increasing thiourea concentration. The rate of grafting increases with an increase of temperature. The effect of acid and water-soluble solvent and certain salts on graft yield has been investigated and a suitable rate expression has been derived.     

Grafting Vinyl Monomers onto Silk Fibers. V. Graft Copolymerization of Methyl Methacrylate onto Silk with Potassium Permanganate as Initiator

The graft copolymerization of methyl methacrylate onto silk fibers in aqueous solution with the use of manganese (IV) ions as initiator was investigated. The rate of grafting was determined by varying monomer, acidity of the medium, temperature, nature of silk, and the reaction medium. The graft yield increases significantly with increase of manganese (IV) concentration up to 15 meq/liter; with further increase of manganese (IV) concentration, the graft yield decreases. The effect of the increase of monomer concentration brings about a significant enhancement in the graft yield up to 7%, and with further increase of monomer concentration the graft yield decreases. The graft yield is considerably influenced by chemical modification prior to grafting. The effect of some inorganic salts and anionic surfactants on the rate of grafting has been investigated.     

Grafting Vinyl Monomers onto Wool Fibers: Graft Copolymerization of Methyl Methacrylate onto Wool Using Ferric Acetylacetonate Complex

The graft copolymerization of methyl methacrylate (MMA) onto native and reduced Indian Chokla wool fibers was studied in aqueous solution using an acetylacetonate complex of Fe(III). Perchloric acid was found to catalyze the reaction. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, and the solvent composition of the reaction medium. The graft yield increases with increasing concentration of the initiator and with increasing temperature. An increase of monomer concentration up to 0.5634 mol/L and of the HClO4 concentration up to 0.01 mol/L increases the graft yield. Reduced and oxidized wools were found to be better substrates than untreated, esterified, cross-linked, and trinitrophenylated wools. Among the various monomers studied, MMA was found to be the most active. A suitable kinetic scheme is proposed. From the activation energy data, average molecular weight, and spectral studies, the reactivity of -SH groups, and the extent of chain transfer is ascertained.     

Grafting onto Cellulose. VI. Graft Copolymerization of Vinyl Acetate by Use of Metal Chelates as Initiators

Graft copolymerization of vinyl acetate (VAc) onto cellulose has been studied in an aqueous medium in the presence of Fe(acac)₃, Al(acac)₃, and Zn(acac)₂ as initiators. Percentage of grafting has been determined as a function of concentration of initiators and monomer, reaction time, and temperature. The reactivities of different metal chelates toward grafting of VAc on cellulose have been determined and were found to follow the order: Zn(acac)₂ > Al(acac)₃ > Fe(acac)₃. A plausible mechanism for grafting involving complex formation between metal chelates and vinyl monomer has been suggested. Several grafting experiments were carried out in presence of CCl₄, CHCl₃, CH₃CH₂CH₂SH and Et₃N. All these additives with the exception of Et₃N were found to suppress grafting.     

Photoinduced Graft Copolymerization. V. Graft Copolymerization of Methyl Methacrylate onto Cellulose in the Presence of N-Bromosuccinimide as Initiator

Abstract

The photoinduced graft copolymerization of methyl methacrylate onto cellulose was studied using N-bromosuccinimide as the photoinitiator. The formation of graft copolymer increases with an increasing amount of cellulose. The graft copolymerization increases with increasing initiator concentration up to 1,25 × 10^?2 M and thereafter it decreases. The percentage of graft increases with increasing monomer concentration up to 46.9 × 10^?2 M and thereafter it decreases. The percentage graft-on increases with increasing temperature. The overall activation energy was computed to be 8.40 kcal/mol. The percentage graft was investigated using different water-miscible organic solvents. The graft copolymerization was also investigated using differently modified cellulose. A possible mechanism for the photo-graft copolymerization onto cellulose is suggested.     

Graft Copolymerization of Methyl Methacrylate onto Nylon 6 Using Thallium(III) Ions as Initiator

Abstract

Graft copolymerization of methyl methacrylate onto nylon 6 was investigated in aqueous perchloric acid medium using thallium(III) ions as initiator. The rate of grafting was evaluated by varying the concentrations of monomer, initiator, acid, and temperature. The rate of grafting was found to increase with an increase of both monomer and initiator concentrations. The graft yield was found to increase with an increase in the acid concentration up to 0.49 mL^?1, and beyond this concentration of perchloric acid the graft yield was found to decrease. It also increased with an increase of temperature. From the Arrhenius plot the overall activation energy was found to be 3.9 kcal/mol. The effects of inhibitors, various solvents, inorganic salts, and swelling agents on graft yield were studied. A suitable kinetic scheme has been proposed and a rate equation has been derived.     

Grafting Vinyl Monomers onto Cellulose. IX. Graft Copolymerization of Methyl Methacrylate onto Cellulose Using Peroxydiphosphate-Fe(ll) and Mn(ll) Redox Systems

The vacuum or inert-atmosphere condensation of diphenyl isophthalate and 2,2′,3,3′-tetraaminobiphenyl to poly-2,2′-(m-phenylene)-5,5′-bibenzimidazole has been investigated. Evidence from polymer and model compound (diphenylbibenzimidazole) spectral studies, elemental analysis, and analysis of volatile effluent indicates that the prepolymer formed at 260 to 300°C contains both benzimidazole and hydroxybenzimidazoline but is essentially free from phenoxybenzimidazole structures. A mechanism involving loss of phenol initially, followed by evolution of water to give benzimidazole structures, is established from experimental evidence. Polymerization in vacuum to 400°C gives the polybenzimidazole.     

Grafting onto Gelatin. II. Graft Copolymerization of Ethyl Acrylate and Methyl Methacrylate onto Gelatin in the Presence of Ce4+ as Redox Initiator

In order to initiate a comprehensive study of graft copolymerization of vinyl monomers onto soluble protein-gelatin, we have studied grafting of ethyl acrylate (EA) and methyl methacrylate (MMA) onto gelatin using eerie ammonium nitrate (CAN) and eerie ammonium sulfate (CAS) as the redox initiator in an aqueous medium. A small amount of mineral acid (HNO₃ with CAN and H2SO4 with CAS) was found to catalyze the graft copolymerization. Graft copolymerization reactions were carried out at different temperatures. Maximum grafting occurred at 65°C both with EA and MMA. Percentage grafting has been determined as function of 1) concentration of monomer (EA and MMA), 2) concentration of initiator (CAN and CAS), 3) concentration of acid (HNO3 and H2SO4), 4) time, and 5) temperature.     

Graft Copolymerization of Methyl Methacrylate on Potato Starch Using Potassium Trioxalatomanganate,K3[Mn(C2O4)3], as Initiator

Graft copolymerization of methyl methacrylate on potato starch was carried out in methanol-water medium at 35°C in the dark using potassium trioxalatomanganate, K₃[Mn(C₂O₄)₃], as initiator. The effect of different methanol-water ratios (v/v), the temperature of polymerization, the initiator concentration, the monomer concentration, the starch content, and the time of polymerization were studied. Percent total conversion, % grafting, and grafting efficiency (%) under different conditions were evaluated and compared. High grafting efficiency (～80%), high % total conversion (～85%), and high % grafting (-95%) were readily obtained. The reaction mechanism for graft copolymer formation is discussed.     

Grafting Vinyl Monomers onto Nylon 6 Fiber. IV. Graft Copolymerization of Ethyl Methacrylate onto Nylon 6 Fiber by Photoirradiation

Grafting of nylon 6 fiber was carried out using ethyl methacrylate (EMA) as the monomer in various water-alcohol systems (i.e., water-methanol, water-ethanol and water-n-propanol; water-alcohol ratio 1:1) at 70°C using a carbon arc lamp as the source of photochemical initiation. Percent graft add-on (% GAO) increases continuously and linearly with an increase in monomer concentration irrespective of the media used. The % GAO, however, decreases with an increase in the alkyl chain length of the alcohol used in the following order: water-methanol > water-ethanol > water-n-propanol. With an increase in the time period of grafting, % GAO and total polymer yield (% TPY) increase continuously in all three media whereas the grafting efficiency (GE) first increases and then falls after reaching a maximum level. Although a similar trend is maintained in the three systems, there is a decrease in overall % TPY and % GAO from the water-methanol system to the water-n-propanol system through the water-ethanol system.     

Grafting Vinyl Monomers onto Silk Fibers. XI. Graft Copolymerization of Methyl Methacrylate onto Silk Using Fe3+-Thiourea Redox System

The results of some investigations into the synthesis and characterization of a new class of oligomers and polymers, the polyselenoacetals, are described.     

Grafting Vinyl Monomers onto Tussah Silk Fiber. I. Graft Copolymerization of Methyl Methacrylate onto Nonmulberry Tussah Silk by Tetravalent Cerium Ion

The graft copolymerization of methyl methacrylate onto nonmulberry natural tussah silk fibers was investigated in aqueous solution using tetravalent cerium as initiator. The rate of grafting was determined by varying the monomer concentration, the cerium (IV) concentration, the temperature, and the nature of the silk. With increasing monomer concentration the graft yield increased (up to 0.657 M) and thereafter decreased. The graft yield also increased with increasing cerium (IV) concentration. The graft-on was influenced by chemical modification of the tussah silk prior to grafting. The effect of certain inorganic salts on the rate of grafting was investigated.     

Grafting Vinyl Monomers onto Poly(ethylene Terephthalate) (PET). IV. Graft Copolymerization of Methyl Methacrylate onto PET Fibers Using Acetyl Acetonate Complexes of Mn(III), Co(III), and Fe(III)

The graft copolymerization of methyl methacrylate onto poly-(ethylene terephthalate) using metal complexes of Mn³⁺, Co³⁺, and Fe³⁺ as initiators was studied. The rate of polymerization, R_p, increased with increasing complex concentrations.

The rate of polymerization was also studied by varying monomer concentrations. Increasing monomer concentrations, the rate of polymerization increases significantly. The graft yield increases with increasing temperature within the range 60–75°C. The graft yield is medium dependent. A suitable kinetic scheme has been pictured and rate equations have been derived.     

Graft Copolymerization of Methyl Methacrylate onto Chitosan Initiated by Potassium Ditelluratocuprate(III)

A novel redox system, potassium ditelluratocuprate(III) (DTC)–chitosan, was employed to initiate the graft copolymerization of methyl methacrylate (MMA) onto chitosan in alkali medium. The effects of reaction variables, such as the initiator concentration, ratio of monomer to chitosan, the pH value, as well as reaction temperature and time were investigated, and the grafting conditions were optimized. Graft copolymers with both high grafting efficiency (>90%) and percentage of grafting were obtained, and the rate of polymerization is higher, which indicated that the DTC–chitosan redox system is an efficient initiator for this graft copolymerization. The structures and the thermal property of chitosan and chitosan–g–PMMA were characterized by infrared spectroscopy (IR), X‐ray diffraction and thermogravimetric analysis (TGA). A mechanism is proposed to explain the generation of radicals and the initiation. The graft copolymer was used as the compatibilizer in blends of terpolyamide and chitosan. The scanning electron microscope (SEM) photographs indicated that the graft copolymer improved the compatibility of the blend.