Nrusingha C. Pati

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

Abstract 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 Cellulose. VI. Graft Copolymerization of Methyl Methacrylate onto Cellulose Using Potassium Permanganate as the Initiator

Abstract The graft copolymerization of methyl methacrylate onto cellulose using tetravalent manganese as the initator has been studied. AII increase in initiator concentration up to 1.0 × 10−2 M increases the graft yield. With a further increase, the graft yield decreases. The graft yield also increases with an increase of monomer concentration and temperature. There is an initial increase in graft yield with acid concentration up to 4.5 × 10−2 M after which the graft yield decreases. The effect of addition of solvents, CuSO4 concentration, and redox system on the rate of grafting has been studied and a suitable kinetic scheme has been pictured.

Grafting Vinyl Monomers onto Cellulose. VIII. Graft Copolymerization of Methyl Methacrylate onto Cellulose Using H2-O2-Cysteine Redox System

Abstract The application of the H2O2-cysteine redox system to induce graft copolymerization of methyl methacrylate onto cellulose was investigated under various conditions. The rate of grafting was determined by varying the concentrations of monomer, initiator, cysteine, acid, and temperature. The effect of some solvents was studied and a suitable reaction mechanism has been proposed.

Aqueous Polymerization of Acrylonitrile Initiated by Potassium Bromate-Thioacetamide Redox System

Abstract The polymerization of acrylonitrile initiated by potassium bromate coupled with thioacetamide was investigated in aqueous solution under nitrogen atmosphere. The effect of monomer, initiator, activator, and acid concentration on the rate of polymerization as well as on maximum conversion was evaluated. The rate of polymerization was found to increase up to 1.25 × 10−3 M of initiator concentration and thereafter it decreased. The rate of polymerization also increased with the monomer and activator concentration up to 1.5078 and 4.0 × 10−3 M, respectively, after which the rate fell. The effect of acid concentration, temperature, and solvents on rate of polymerization has been studied and a suitable kinetic scheme has been pictured.

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

Abstract The application of peroxydiphosphate coupled with bivalent metal ions like Fe(n) and Mn(II) to induce graft copolymerization of methyl methacrylate onto cellulose fibers by varying the concentrations of monomer, initiator, acid, reducing agent, solvents, and temperature has been studied. The rate of grafting increases progressively with increasing monomer and reducing agent concentrations. The rate of grafting also increases with peroxydiphosphate concentration up to 10.0 × 10−3 M and with sulfuric acid concentration up to 9.0 × 10−2 M after which it decreases. The effects of addition of some solvents and temperature on graft yield were also studied. The effect of modified cellulose on the rate of grafting was also studied. Both systems have been investigated under identical conditions. A larger percentage of grafting was observed in the case of Mn(II) than of Fe(II). A suitable kinetic scheme has been developed, and rate equations have been derived.

Polymerization of Methyl Methacrylate Initiated by Thiourea-V5+ Redox System

Abstract Kinetics of the vinyl polymerization of methyl methacrylate initiated by V5+-thiourea redox system were investigated in aqueous sulfuric acid in the temperature range of 35 to 50°C, and the rate of polymerization, V5+ disappearance, etc. were measured. From the results it was concluded that the polymerization reaction is initiated by an organic free radical arising from the V5+-thiourea reaction and terminated by V5+ ions. The effects of certain organic solvents (water miscible) and salts on the rate of polymerization have been studied. The rate parameters have been evaluated.

Vinyl Polymerization Initiated by Peroxydiphosphate. IV. Polymerization of Acrylonitrile Initiated by Peroxydiphosphate-Thioacetamide Redox System

Abstract The kinetics of the aqueous polymerization of acrylonitrile initiated by the peroxydiphosphate-thioacetamide redox system was investigated at 35, 40, and 50°C. The rates of polymerization were measured at different concentrations of oxidant, activator, and monomer. Peroxydiphosphate alone did not initiate polymerization under deaerated and undeaerated conditions. Addition of certain water-miscible organic solvents and neutral salts depress the rate and conversion. On the basis of experimental observations of the dependence of the rate of polymerization on various variables, a suitable kinetic scheme has been proposed.

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

Abstract The graft copolymerization of methyl methacrylate onto silk fibers initiated by the ferric chloride-thiourea redox system has been investigated in aqueous medium. The rate of grafting was calculated by varying the concentrations of monomer, initiator, and thiourea, the acidity of the medium, and the temperature. The rate of grafting increases significantly with an increase of [FeCl3] up to 1.25 × 10−3 M and thereafter it slows down. The rate of grafting also increases with an increase of [thiourea] and [HClO4] up to 2.5 × 10−3 and 23.325 × 10−1 M, respectively, and thereafter it decreases. The graft percezage increases with an increase of the monomer concentration. The effect of some inorganic salts, solvents, and surfactants on the rate of grafting has also been investigated.

Grafting Vinyl Monomers onto Wool Fibers. VI. Graft Copolymerization of Methyl Methacrylate onto Wool Using Tetravalent Manganese-Oxalic Acid Redox System

Abstract Graft copolymerization of methyl methacrylate onto wool induced by the permanganate-oxalic acid redox system was investigated in aqueous medium. The rate of grafting was determined by varying the concentrations of monomer, oxalic acid, permanganate, acidity of the medium, temperature, and the reaction medium. The graft yield increases significantly with increasing oxalic acid concentration up to 1.5 × 10−-2 M and thereafter it decreases. The graft yield also increases wTth an increase of the monomer concentration, initiator concentration, acid concentration, and temperature up to a certain range and then decreases. The effect of some inorganic salts and surfactants on the rate of grafting has also been investigated and a suitable reaction mechanism has been proposed.

Vinyl Polymerization Initiated by Metal Chelates. III. Polymerization of Methyl Methacrylate Initiated by Vanadium(IV) Acetylacetonate Chelates

Abstract The polymerization of methyl methacrylate initiated by the vanadium acetylacetonate complex was investigated under a nitrogen atmosphere at 50°C. The effect of concentration of monomer, complex, acid, dioxane, inhibitor, and the effect of temperature on the rate of polymerization were studied. The rate of polymerization was found to increase upon increasing the concentrations of the monomer, the initiator, and the acid. The overall activation energy has been computed from the Arrhenius plot and a suitable kinetic scheme has been proposed.