790 Advances in Environmental Biology, 6(2): 790-794, 2012 ISSN 1995-0756 This is a refereed journal and all articles are professionally screened and reviewed ORIGINAL ARTICLE Corresponding Author Mohammad Sadeghi, Chemistry Department, Science Faculty, Islamic Azad University, Arak Branch, Arak, Iran. Tel: +98-861-3670017, Fax: +98-861-3670017 E-mail: m-sadeghi@iau-arak.ac.ir Investigation effective parameters onto γ-radiation Graft Polymerization Acrylamide onto Carboxymethylcellulose Fatemeh Shafiei, Mohammad Sadeghi and Esmat Mohammadinasab Chemistry Department, Science Faculty, Islamic Azad University, Arak Branch, Arak, Iran. Fatemeh Shafiei, Mohammad Sadeghi and Esmat Mohammadinasab; Investigation effective parameters onto γ-radiation Graft Polymerization Acrylamide onto Carboxymethylcellulose ABSTRACT The monomer, acrylamide, was graft copolymerized onto Carboxymethylcellulose (CMC) using γ-rays as initiator. The reactions were carried out in a homogenous aqueous medium. The results showed that the thermal stability of grafted polyacrylamide samples was remarkably improved. A plausible mechanism of grafting has also been suggested. The effect of various factors affecting on grafting, i.e. dose of δ-rays and concentration of the monomer and polysaccharide as well as the reaction temperature were studied by conventional methods to achieve the optimum grafting parameters. Key words: Carboxymethyl Cellulose, Acrylamide, γ-radiation Graft Polymerization Introduction Graft copolymerization is an attractive means for modifying base polymers because grafting frequently results in the superposition of properties relating to the backbone and pendant chains. Considerable interest has been focused on chemical modification by free radical graft copolymerization of hydrophilic and hydrophobic vinyl monomers biopolymers such as polysaccharides [1-4]. These biodegradable and low cost graft copolymers, with new properties, can be used in many applications such as textiles, paper industry, agriculture, medical treatment and also in petroleum industry as flocculants and thickening agents [5-9]. Graft copolymers are prepared by first generating free radicals on the polysaccharide backbone and then allowing these radicals to serve as macroinitiators for the vinyl monomers. Graft copolymerization can be carried out with different initiator systems. Among them, potassium persulfate, ammonium persulfate, benzoyl peroxide, azo bisisobutyronitrile, and ceric ammonium nitrate are widely used for the synthesis of graft copolymers [10]. Radiation grafting technology is well established and accepted by industry. Radiation polymerization, radiation crosslinking and controlled degradation of polymers comprise most of commercial applications of radiation technology [11-12]. The chosen polysaccharide for modification, i.e. Carboxymethylcellulose (CMC), is the most well- known and most important type of polysaccharide. Carboxymethylcellulose sodium salt (CMC) is the first water soluble ionic derivative of cellulose prepared in 1918 and produced commercially in the early 1920’s in Germany. It has been the most important ionic cellulose ether with a worldwide annual production of 300,000 tons. It is widely used in pharmaceuticals, detergents, cosmetics, foods, paper and textile industries due to its viscosity- increasing and emulsifying properties. However, it may need to be further modified for some special applications. Of the monomers grafted, acrylamide has been the most frequently used one, mainly due to its highest grafting efficiency [13], improving the thermal resistance of the graft copolymer [14], and also the subsequent alkaline hydrolysis of the grafting product to obtain water absorbents [15]. Results and Discussion Graft copolymerization mechanism: The mechanism of grafting acrylamide onto carboxymethylcellulose (CMC) using γ-rays as an initiator is shown in the Scheme 1. It should be mentioned that during the irradiation of AAm, CMC and water ternary mixture, most of the energy is absorbed by water and only a very small fraction by other components. Thus, the initiation occurs mainly by an indirect effect. Hydroxyl radicals, formed during irradiation, add to one side of the AAm