Preparation Of Pesticide In Water Emulsions Stabilized By Cholesteryl Grafted Alginate/APG And Its Forming Mechanism Of Synergistic Stable System

Alginate is a kind of non-toxic, biocompatible, and biodegradable natural macro molecules in vivo. Presently, it has been widely used in the food, textile, printing, pharmaceutical and other industries. In this thesis, a kind of alginate derivative CSAD was prepared via hydrophobic modification Simultaneously, this alginate derivative was used to investigate its effect of physicochemical properties to pesticide Lambda-cyhalothrin in water emulsions that stabilized by green surfactant alkyl poly-glycosides (APG). Then the corresponding security, environmental, high efficiency and stable water emulsions were prepared. Furthermore, mechanism for CSAD/APG stabilized emulsion was discussd in the research. The main findings are as follows:The structure and properties of the synthetic polymer products (CSAD) were characterized by Infrared (FT-IR), nuclear magnetic resonance (1H NMR), thermal gravimetric (TG) and fluorescence spectroscopy. The alginate derivatives were grafted hydrophobic chain or hydrophobic group onto the backbone chain of alginate. In addition, the synthesized polymers were amphiphilic, the critical aggregation concentration (CAC) of alginate derivatives in aqueous solution was less than that of Alg-Na, was only about0.55g/L.The effect sodium alginate derivative and nonionic surfactant alkyl poly-glyco sides (APG) on the physicochemical properties of pesticide Lambda-cyhalothrin in water emulsions which were prepared by inversed phase emulsification was systematically investigated by standing stability, centrifugal stability, dispersion stability, crystallization temperature, droplet size, Zeta potential, and viscosity. Results showed that the emulsions displayed the excellent stability in the CSAD concentration range of0.2-1.0g/L, the centrifugal stability index of the best CSAD concentration in water emulsions was85.19%. Zeta potential value increased gradually to-41.9mV followed by a gradual decrease. However, the stability sharply decrease with the increasing polymer concentration. Furthermore, differential scanning calorimetry (DSC) technology was introduced to study freeze-thaw stability of pesticide emulsions. The data showed that the freezing point shifted from-18.06?to-13.25?with CSAD concentration. Then the mechanism for CSAD/APG synergetic stabilized emulsion was proposed.After the the mechanism was put forward, synergistic stabilized emulsions of alginate derivative and APG were prepared, and investigated the effects of theree factors influencing the stability of the emulsion, including the different molecular weight of CSAD, ionic strength and pH value of the aqueous phase. The data indicated that CSAD/APG emulsions displayed the excellent stability, the emulsion volume fraction was still above90%, after3months later. With low molecular weight, the alginate derivatives were easier to cooperate with APQ the stability of the emulsions were becoming better. When the pH=8.5, the alginate derivative preferably exhibited amphiphilic, then formed viscous-elastic interfacial films for prevent oil drop coalescence.