GRAFT COPOLYMERIZATION OF VINYL MONOMERS ONTO STARCH INITIATED BY TRANSITION METAL-THIOUREA REDOX SYSTEMS

摘要

In this paper, the capabilities of grafting acrylonitrile （AN） onto starch initiatedby Fe（III）-TU, V（V）-TU, Cr（VI）-TU, Mn（VII）-TU redox systems were compared in thepresence of sulfuric acid of different concentrations. It was shown that the grafting capabili-ty of Mn（VII）-TU is the highest in these initiating systems. Using Mn (VII-TU as initia-tor, the effects of various acids （HClO₄, H₂SO₄, HNO₃, HCl） on the graft copolymerizationof acrylonitrile onto starch were discussed, and the capabilities of graft copolymerizationof methyl methacrylate （MMA）, acrylamide （AM）, acrylic acid （AA） onto starch wereinvestigated. The experimental results show that the order of the influences of differentacids is HClO₄H₂SO₄HNO₃HCl, and the order of grafting capabilities of differentmonomers grafted onto starch is MMAANAMAA. The structure and morphology ofgraft copolymers were studied with infrared spectroscopy and scanning electron microscopy.The size, shape and roughness of surface of the grafted starch granules are changed aftergrafting.