Effect of various initiators on molar mass determination of hydrolyzed potato starch-acrylamide graft copolymers

This study is concerned with synthesis, characterization and properties of graft copolymer produced from hydrolyzed potato starch and acrylamide using various initiators (azobisisobutyronitrile, potassium persulfate and benzoyl peroxide). Starch hydrolysis was performed in order to reduce molecular mass. Acrylamide was grafted on shorter starch macromolecules creating side branches on the main chain resulting in a product that could be used in textile finishing more successfully. Various initiators were used, primarily, to produce graft monomer on the starch and also to obtain thinner or thicker packaging of side chains that can have a great influence on the behavior of textile yarns impregnated with these copolymers. Benzoyl peroxide, as initiator, proved to be very successful in grafting of acrylamide on hydrolyzed starch, in terms of yield, graft percentage and efficiency results. Grafting in the presence of azobisisobutyronitrile and potassium persulfate as initiators has slightly better monomer to polymer conversion values. FTIR spectra of hydrolyzed and grafted starch confirm by their characteristic bands that grafting was successful. Residual amounts of monomer in copolymer and molar mass distribution were determined by chromatography. Results show that the highest quantity of monomer is found in the sample of hydrolyzed starch grafted in the presence of potassium persulfate. Molar masses of hydrolysate and copolymer show differences ranging from 1∙102 to 2∙107 g/mol. Results of sizing using grafted starch show that sized yarns had higher strength (tenacity) and lower elongation. Grafted hydrolyzed starch, as an agent for cotton yarn sizing, gives better results than non grafted starch, especially regarding sizing uniformity, yarn mechanical parameters and easier removal in following desizing process