H. C. Trivedi

Ceric-induced grafting of acrylate monomers onto sodium alginate

Abstract The graft copolymerization of methyl acrylate (MA) and methyl methacrylate (MMA) onto sodium alginate (SA) with ceric ammonium nitrate (CAN) as a redox initiator in an aqueous medium has been studied. The optimized reaction conditions affording the maximum percentage of grafting of MA and MMA onto SA are determined by varying the concentrations of nitric acid, ceric ammonium nitrate, SA, MA and MMA, and also temperature and time. A comparison of the reactivity of the acrylate monomers with that of acrylonitrile has been made.

Ceric-induced Grafting of Acrylonitrile onto Sodium Alginate

Acrylonitrile (AN) was grafted onto sodium alginate (SA) using ceric salt as initiator. The optimized reaction conditions affording the maximum percentage of grafting are determined by varying the concentrations of nitric acid, ceric ammonium nitrate, SA and AN, and also temperature and time. The results are discussed and the efficiency of ceric salt is compared with that of Fentons reagent.

Ceric-induced grafting of acrylonitrile onto sodium alginate: kinetics and mechanism and effects of the reaction medium

The kinetic scheme of free radical graft copolymerization of acrylonitrile (AN) onto sodium alginate, using ceric ammonium nitrate as an initiator, has been proposed and equations relating the values of Rp, Rr and Rh are also suggested. The results have been found to be in good agreement with the proposed mechanism. The per cent grafting of AN onto sodium alginate has also been determined as a function of composition of the mixed solvents comprising methanol: water, ethanol: water, n-propanol:water and n-butanol: water systems. The reaction medium has been found to play an important role in graft copolymerization. The results of the effect of the reaction medium on grafting are also discussed.

Grafting of Vinyl Monomers onto Sodium Salt of Partially Carboxymethylated Guar Gum: Comparison of Their Reactivity

Abstract: The optimum reaction conditions for affording maximum percentage of grafting have been established in the case of grafting of acrylonitrile (AN), methyl acrylate (MA), methyl methacrylate (MMA), and ethyl methacrylate (EMA) onto sodium salt of partially carboxymethylated guar gum (Na-PCMGG, ) using ceric ammonium nitrate (CAN) as a redox initiator in an aqueous medium by using different reaction parameters. Under the optimized reaction conditions, the following reactivity order of monomers was observed: AN > MA > MMA > EMA. The plausible explanation for this observed order of reactivity has been furnished. The thermal behavior of different graft copolymers of Na-PCMGG ( ) has been studied at four different heating rates by thermogravimetric analysis (TGA) and the results obtained have been analyzed by employing Osawa as well as Freeman-Carroll (multiple heating rate) methods for the evaluation of activation energy (E). The values of E calculated at various constant conversions as well as the average activation energy values (for both the steps of thermal degradation) calculated according to Osawa as well as Freeman-Carroll methods, for all the four different graft copolymers of Na-PCMGG ( ), have been found to be in good agreement with each other. The evidence of grafting has been ascertained by spectral (IR/1H-NMR) and scanning electron microscopic (SEM) methods.

Transitions of Cellulose Acetate

Abstract The transitions of cellulose acetate (40% acetyl) have been studied by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Two distinct transitions, one at 63°C and the other at 218°C, have been observed. An exothermic peak at 234°C is attributed to crystallization and is analyzed by the Kissinger and the Ozawa methods for calculating the various kinetic parameters.

Modification of sodium salt of partially carboxymethylated tamarind kernel powder through grafting with acrylonitrile: Synthesis, characterization and swelling behavior

A graft copolymer of polyacrylonitrile (PAN) with sodium salt of partially carboxymethylated tamarind kernel powder (Na-PCMTKP,

Ceric-induced grafting of acrylonitrile onto sodium salt of partially carboxymethylated starch

\overline {DS} = 0.15

Modification of sodium salt of partially carboxymethylated guar gum by graft copolymerization with methyl acrylate

) was synthesized by using ceric ammonium nitrate (CAN) as a redox initiator in an aqueous medium. The optimum reaction conditions for affording maximum percentage of grafting were established by successively varying reaction conditions such as concentrations of nitric acid, CAN, monomer (AN) as well as reaction time, temperature and amount of substrate. The influence of these reaction conditions on the grafting yields was discussed. The kinetic scheme of free radical graft copolymerization was proposed and the experimental results were found to agree very well with the proposed kinetic scheme. The graft copolymer (Na-PCMTKP-g-PAN, percentage of grafting G = 413.76% and percentage of grafting efficiency GE = 96.48%) sample synthesized under the established optimized reaction conditions was hydrolyzed by 0.7 mol·L−1 NaOH solution at 90–95°-C to yield the superabsorbent hydrogel, H-Na-PCMTKP-g-PAN. The swelling behavior of the hydrogel was studied by carrying out its absorbency measurements in low conductivity water, 0.15 mol·L−1 salt (NaCl, CaCl2 and AlCl3) solutions and simulated urine (SU) solution at different timings. FTIR, TGA and SEM techniques were used to characterize the products.