Investigation On The Effectiveness Of Redox Initiators Used In The Preparation Of Grafted Starch Sizes

Grafted starch is developed through graft copolymerization of starch with hydrophilic and hydrophobic monomers. In order to enhance the grafting efficiency, reduce the cost and screen the initiators which has higher initiating efficiency, extensive source and higher ratio of performance to price in the preparing grafted starch, this study chooses acrylic acid (AA) and methyl acrylate (MA) as the models of hydrophilic and hydrophobic monomers, respectively. According to available literatures, initiation effects of five redox systems under their optimal conditions in preparing grafted starch are investigated. The five redox systems are Ce(NH4)2(NO3)6, FeSO4/H2O2, KMnO4/C6H8O7, K2S2O8/Na2S2O3, and (NH4)2S2O8/NaHSO3. It was found that, while initiating the graft copolymerization of hydrolyzed starch with AA or MA, Ce(NH4)2(NO3)6 exhibited the best initiation effect, (NH4)2S2O8/NaHSO3 and FeSO4/H2O2 were the secondary, and K2S2O8/Na2S2O3 and KMnO4/ C6H8O7 were the worst. (NH4)2S2O8/NaHSO3 and FeSO4/H2O2 can be used in the preparation of grafted starch sizes.Trough maleic anhydride pretreatment before the graft copolymerization, the graft efficiency and behaviors of grafted starch sizing agents both could be enhanced, In order to enhance the grafting efficiency further, reduce the cost and screen the initiators which has higher initiating efficiency, extensive source and higher ratio of performance to price in the preparing grafted starch, the study selects maleate starch that contains C=C double bonds as substrate to develop grafted starch sizes. The'redox systems employed were Ce(NH4)2(NO3)6, (NH4)2S2O8/NaHSO3, FeSO4/H2O2, and H2NCSNH2(TU)/H2O2. Thereinto, Ce(NH4)2(NO3)6, (NH4)2S2O8/NaHSO3 and FeSO4/H2O2 were chosen from above five redox systems according to their initiation effect and H2NCSNH2(TU)/H2O2 was selected in accordance with existing theory. It was found that, while initiating the graft copolymerization of maleate starch with AA or MA, Ce(NH4)2(NO3)6 exhibited the best initiation effect, H2NCSNH2(TU)/H2O2 and FeSO4/H2O2 were the secondary, and (NH4)2S2O8/NaHSO3were the worst. H2NCSNH2(TU)/H2O2 and FeSO4/H2O2 can be used in the preparation of grafted starch sizes through esterified with maleate anhydride.In order to study the effect of FeSO4/H2O2 initiator on the sizing performance of the graft copolymer of starch with acrylates and select graft monomer which is appropriate for the preparation of grafted starch sizes through the evaluation of sizing performance of MES-g-Polyacrylates, this investigation chooses FeSO4/H2O2 initiator which is low in price and shows better initiation effect while preparing MES-g-PMA and develops a series of graft copolymer of starch with acrylates. It was found that choosing FeSO4/H2O2 as initiator and ethyl acrylate as monomer to develop MES-g-Polyacrylates can obtain sizing agents with high performance.