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The effect of reaction conditions on the grafting parameters during the grafting of methacrylamide (MAM) onto guar‐gum (GOH) using potassium chromate/malonic acid redox pair was studied under nitrogen atmosphere at different temperatures. On increasing the chromate ion concentration (from 3.5×10–3 mol·dm–3 to 20.0×10–3 mol·dm–3) grafting parameters were found to increase. Grafting ratio, efficiency, and add on were found to increase with the increase in malonic acid concentration from 3.5×10–3 mol·dm–3 to 10.0×10–3 mol dm–3. It was observed that maximum efficiency was obtained when the monomer concentration was 20.0×10–3 mol·dm–3. With increasing hydrogen ion concentration, grafting parameters were found to increase. Homopolymer concentration, however, was found to decrease with increasing hydrogen ion concentration. Optimum temperature and time for grafting of MAM onto guar gum were found to be 35°C and 120 min respectively. The graft copolymer was characterized by IR spectroscopy and thermogravimetric analysis.

The aim of this study was to examine the synthesis of a graft copolymer of chitosan and methacrylic acid (MAA) by free-radical polymerization with a potassium peroxymonosulfate/cyclohexanone (CY) redox system in an inert atmosphere. The optimum reaction conditions affording maximum grafting ratio (%G), grafting efficiency (%E), add on (%A), and conversion (%C) were determined. The grafting parameters were found to increase with increasing concentration of MAA up to 24 Â 10 À2 mol/dm 3 , but thereafter, these parameters decreased. With increasing concentration of peroxymonosulfate from 0.6 Â 10 À2 to 1.2 Â 10 À2 mol/dm 3 , %G, %A, and %E increased continuously. All of these grafting parameters increased with increasing concentration of CY up to 1.2 Â 10 À2 mol/dm 3 , but beyond this concentration, the grafting parameters decreased. With vari-ous concentrations of chitosan from 0.6 to 1.4 g/dm 3 , the maximum %G, %A, and %E were obtained at 1.4 g/dm 3 . %G, %A, and %C decreased continuously with various concentrations of hydrogen ions from 2 Â 10 À3 to 6 Â 10 À3 mol/dm 3 . The grafting parameters increased with increasing temperature up to 35 C, but thereafter, these parameters decreased. With increasing time period of reaction from 60 to 180 min, %G, %A, and %E increased up to 120 min, but thereafter, these parameters decreased. The graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis.

ABSTRACT:The effect of the reaction conditions on the grafting parameters during grafting of 2-acrylamido-2-methyl-1-propanesulfonic acid onto sodium carboxymethylcellulose using H 2 O 2 /Fe ϩ2 redox pair are studied at 30°C. The grafting ratio, add on, and conversion initially increase with the H 2 O 2 concentration in the range of (10.0 -15.0) ϫ 10 Ϫ2 mol dm Ϫ3 . Thereafter, these parameters decrease with the H 2 O 2 concentration. The grafting ratio, add on, and conversion increase when increasing the ferrous ion concentration from (0.5 to 4.0) ϫ 10 Ϫ2 mol dm Ϫ3 and decrease with a further increase in the concentration. It is observed that the grafting ratio and add on increase with the monomer concentration, whereas the conversion decrease. The hydrogen ions seem to be facilitating the grafting reaction up to a certain concentration and after this concentration seem to be retarding the process. The grafting ratio, add on, and conversion decrease with the sodium carboxymethylcellulose concentration. When increasing the time period from 60 to 90 min, the grafting parameters increase but decrease thereafter. Similarly, when increasing the temperature from 25 to 30°C, the grafting parameters increase and decrease thereafter.

A previously unreported graft copolymer of xanthan gum (XOH) with acrylic acid was synthesized and the reaction conditions were optimized using a potassium monopersulfate (PMS)/Fe 2ϩ redox pair. Grafting ratio, add on, and conversion increase with an increase in the ferrous ion concentration (2.0 ϫ 10 Ϫ3 to 5.0 ϫ 10 Ϫ3 mol dm Ϫ3 ) and PMS concentration (1.0 ϫ 10 Ϫ3 to 4.0 ϫ 10 Ϫ3 mol dm Ϫ3 ). It was observed that grafting takes place efficiently when the acrylic acid concentration and temperature were 5.0 ϫ 10 Ϫ2 mol dm Ϫ3 and 35°C, respectively. Samples of xanthan gum and xanthan gum-g-acrylic acid were subjected to thermogravimetric analysis with the objective of studying the effect of grafting of acrylic acid on the thermal stability of xanthan gum. The graft copolymer was found to be more thermally stable than xanthan gum.

Guar gum has been modified by grafting 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) onto guar gum in aqueous medium. The graft co-polymerization reaction was studied under different experimental conditions, such as varying monomer concentration, redox pair concentration, backbone concentration, hydrogen ion concentration, time of reaction and temperature. It has been observed that grafting ratio, add on, conversion and rate of grafting decrease on increasing the bromate ion concentration. A similar trend has been observed with hydrogen ion concentration. The grafting ratio, add on, conversion and rate of grafting have been found to increase with mandelic acid concentration. On increasing the AMPS concentration in the concentration range 2.0 × 10 −2 to 8.0 × 10 −2 mol dm −3 , the grafting parameters show increasing trend. However, increase in guar gum concentration decrease the grafting ratio, add on and rate of grafting while conversion increases with increase in guar gum concentration. All the grafting parameters show increasing trend with time and the optimum temperature has been observed as 35 • C. The graft co-polymer has been characterized by infrared spectroscopy and thermogravimetric analysis.