Grafting of vinyl monomers onto silk fibers: Trivalent‐manganese‐initiated graft copolymerization of acrylamide onto silk fibers

A graft copolymer based on a polysaccharide (sodium salt of carboxymethylcellulose) and a vinyl monomer (acrylamide) has been synthesized in a nitrogen atmosphere, and its reaction conditions have been optimized for a better yield with ferrous sulfate and potassium bromate as a redox initiator. The effects of ferrous ion, bromate ion, hydrogen ion, sodium carboxymethylcellulose, and acrylamide along with the reaction time and temperature have been studied through the determination of the grafting parameters: the grafting ratio, add‐on, conversion, efficiency, homopolymer, and rate of grafting. The maximum yield has been found to occur when the acrylamide concentration is 8.0 × 10−2 mol/dm3, whereas the maximum conversion occurs at a minimum concentration of acrylamide, that is, at 3.0 × 10−2 mol/dm3. The grafting parameters have been found to increase with an increasing concentration of the redox initiator (Fe2+, from 2.0 × 10−3 to 10.0 × 10−3 mol/dm3; BrO 3−, from 2.2 × 10−3 to 4.0 × 10−3 mol/dm3). The maximum efficiency occurs with a reaction time of 210 min. The rate of grafting has been found to be maximum up to 60 min; after that, it decreases rapidly. In this article, it is shown that the hydrogen ion leads to a very clear decrease in the grafting parameters as its concentration increases from 2.1 × 10−3 to 11.3 × 10−3 mol/dm3. Grafted gum and ungrafted gum have been characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. A probable mechanism has been suggested for graft copolymerization. It has been observed that the graft copolymer is thermally more stable than the parent backbone. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Section: Resultssupporting

confidence: 84%

One‐pot synthesis of a polysaccharide‐based graft copolymer with an efficient redox pair (Fe²⁺/BrO₃⁻)

Kumar

Srivastava

Behari

2007

“…This effect could be explained as follows: (1) the rate of production of primary free radicals increased, and (2) the rate of diffusion of ACM onto the guar gum matrix increased with increasing temperature. A similar explanation was given by Samal and coworkers in the grafting of ACM on to nylon 6 30 and silk fibers 31 However, with further increasing temperature beyond 35 C, %G, %E, %A, and R g decreased. The total conversion increased with increasing temperature from 25 to 45 C, and this may have been due to the formation of a large quantity of homopolymer.…”

Section: Effect Of the Temperaturesupporting

confidence: 60%

Vanadium(V)/mandelic acid initiated graft copolymerization of acrylamide onto guar gum in an aqueous medium

Srivastava

Mishra

Singh

et al. 2009

ABSTRACT:The graft copolymerization reaction of acrylamide onto guar gum with a vanadium(V)/mandelic acid redox pair was carried out in an N 2 atmosphere. The optimum concentrations of vanadium(V), mandelic acid, hydrogen ions, acrylamide, and guar gum for the maximum percentage of grafting were 6.0 Â 10 À3 , 2.0 Â 10 À2 , 55.0 Â 10 À2 , and 20.0 Â 10 À2 mol/dm 3 and 110.1 Â 10 À2 g/dm 3 , respectively. The optimum time and temperature of reaction were 90 min and 35 C, respectively, and during the study of [H þ ] variation, a prompt change in the value of the grafting parameters was observed. The maximum percentage of swelling of the graft copolymer was achieved at room temperature in 1 h. Studies of the flocculation, viscosity, and metal-ion absorption capacity were also performed. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analyses, which showed that the grafted guar gum was thermally more stable than the ungrafted guar gum.

“…Figure 4 shows that the graft yield percentage increased initially with the rise in the temperature from 30 to 60°C for both MMA and EMA and then fell with a further increase in the temperature. The increase in the temperature increased the rate of diffusion of the monomers into the fiber matrix 12. Hence, a rise in the temperature up to 60°C increased the rate of production of active free radicals, and this increased the number of grafting sites at a higher rate.…”

Section: Resultsmentioning

confidence: 99%

Effect of grafting methacrylate monomers onto jute constituents with a potassium persulfate initiator catalyzed by Fe(II)

Mondal

Haque

2006

The graft copolymerization of methyl methacrylate and ethyl methacrylate monomers onto jute fiber was carried out in an aqueous medium with potassium persulfate as an initiator under the catalytic influence of ferrous sulfate in the presence of air. The effects of parameter variables, such as the monomer, initiator, and catalyst concentrations, the reaction time, and the temperature, on grafting and the effect of grafting the monomers onto jute constituents were studied. The degree of grafting depended on the kinds of monomers and the parameter variables.The maximum graft yield percentages with methyl methacrylate and ethyl methacrylate under optimized conditions were 18.9 and 38.8%, respectively, and the grafting onto jute fiber was largely affected by one of its main constituents, such as hemicellulose. The graft copolymers were characterized, and their improved properties were also examined.