B. C. Singh

Graft copolymerization of methyl methacrylate onto jute fiber initiated by cerium(IV)–DMSO redox initiator system

The kinetics of graft copolymerization of methyl methacrylate (MMA) onto chemically modified jute fibers initiated by the Ce(IV)–DMSO redox system was studied in the temperature range of 40–60°C. By studying the effects of the concentration of the monomer, Ce(IV), and DMSO on the rate of grafting, the optimum conditions for grafting were determined. Also, the effect of temperature, time, concentration of the acid, the amount of jute fiber, and some inorganic salts and organic solvents on the rate was investigated. A kinetic scheme was proposed on the basis of the experimental findings. Infrared spectra of chemically modified jute and grafted jute was investigated. More than 120% of grafting could be achieved with the present system. The characterization of MMA-grafted chemically modified jute by TGA and DTA studies was made. The thermal stability of the jute fibers was improved by grafting.

Characterization of poly(vinyl alcohol) grafted with acrylic acid and methylmethacrylate using a Ce(IV) glucose redox system

Poly(vinyl alcohol) (PVA) is a well-known biomedical polymer and is biocompatible. Methylmethacrylate and acrylic acid monomers were grafted onto PVA using a Ce(IV)–glucose redox system at three different temperatures (35, 45, and 55°C) under nitrogen atmosphere. More than 80% grafting could be achieved in the process. The grafted PVA was characterized through infrared spectra, thermal decomposition studies [thermogravimetric analysis (TGA) and decomposition thermal grafting (DTG)], differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The thermal stability and other properties of grafted PVA related to medical applications was found to be better than those of ungrafted PVA.

Graft copolymerization of acrylic acid onto biomedical polyvinyl alcohol initiated by Ce(IV)-glucose redox system : Part 2

Abstract Graft copolymerization of acrylic acid onto polyvinyl alcohol was carried out using a Ce(IV)-glucose redox system in an aqueous sulfuric acid medium under nitrogen atmosphere. The optimum conditions for grafting were determined by studying the effects of concentrations of metal ion, glucose, monomer, and acid on the percentage of grafting. The graft yield was influenced by reaction time, temperature, the amount of polyvinyl alcohol, some organic solvents, and inorganic salts. More than 80% graft yield could be achieved with the. present system. A suitable kinetic scheme is proposed on the basis of experimental findings. ∗ Part 1: J. T. R. Chem., 2(2), 53-60 (1995).

Effect of Toluene on the Kinetics of Ce(IV)-Ion-Initiated Grafting of Methyl Methacrylate onto Chemically Modified Jute Fibers

Abstract A study of the graft copolymerization of methyl methacrylate onto jute fiber using Ce(IV) and toluene has been carried out. The effects of concentration of monomer, Ce(IV), and toluene on graft yield have been studied. The effects of time, temperature, acid, amount of jute fiber, and some inorganic salts and organic solvents on graft yield have also been investigated. The investigation includes characterization of the grafted fiber by infrared and thermo-gravimetric studies. Grafting improves the thermal stability of jute fibers. More than 200% graft yield was achieved in the present investigation.

Radical-Initiated Homopolymerization of Acrylonitrile in the Presence of Ce(Iv)-Hippuric Acid in Iviicellar Phase: A Kinetic Study

Abstract Polymerization of acrylonitrile using Ce(IV) as initiator in the presence of hippuric acid in aqueous sulfuric acid solution catalyzed by N-cetyl trimethyl ammonium bromide (NCTAB) was studied kinetically. The polymerization experiment was carried out in the temperature range 35°-55°C. The rate of polymerization (R p) increases with increasing concentration of NCTAB and it is found to be proportional to the concentration of acrylonitrile. Comparisons were made of the effect of different organic substrates and different miceiles on the rate of polymerization. Various effects such as effects of concentration of metal ion, ernulsi-fier, monomer, sulfuric acid, organic solvents, and inorganic salts on R p were also investigated. The remarkable feature of the investigation involves the enhancement of R p in the presence of micelles; a suitable mechanism for the derivation of the rate expression is proposed and optimum conditions are predicted. From the Arrhenius plot, the energy of activation (E A) wa...

Kinetics of Retarded Polymerization: Investigation of the Retardation of Peroxydisulfate/Thiourea-Initiated Polymerization of Acrylonitrile by Phenol

Abstract The mechanism and kinetics of retardation of peroxydisulfate/thiourea-initiated polymerization of acrylonitrile (AN) by phenol have been studied in the temperature range of 40°–50°C. The effects of the concentration of retarder (phenol), monomer (M), peroxydisulfate (S2O8 2-), and thiourea (TU) on polymerization have been studied. The most remarkable observation in the present investigation is the positive intercept obtained from the plot of [M]/R p vs. 1/[M]. A reaction mechanism has been suggested and a suitable rate law has been proposed on the basis of experimental findings.

Studies on Aqueous Polymerization of Acrylqnitrile Initiated by Ce(IV)-DMSO

Abstract Aqueous polymerization of acrylonitrile initiated by the Ce(IV)-DMSO redox system was studied in the temperature range of 40°-60°C. The rate of polymerization R p was found to be approximately proportional to [M]3/2 within the range of monomer concentration of 0.32–1.2 mL-1. Effects of time and concentration of Ce(IV), DMSO, H2SO4, and salts were studied. The overall activation energy for the polymerization reaction was estimated to be 4.606 kcal/mol. A suitable kinetic scheme was proposed in the light of these experimental results. Kinetic analysis shows that the mutual termination predominates over linear termination.