No abstract

For the first time, the main characteristics of the polymeric materials are considered for understanding their possible application in ecological sand-fixing. In this investigation, two emulsions, named as E2, a poly(vinyl acetate) emulsion, and E7, a vinyl acetateethylene copolymer emulsion, have been selected for a series of tests related to the practical requirements for ecological sand-fixing. Besides the sand-fixing properties and the thermal aging and freeze-thaw stabilities of the emulsions, their effects in increasing the growth of both microbes and plants in sandy lands have been evaluated by field experiments in Kerqin Sandy Land of China, and the relationship between the performance and structure of the two emulsions has also been described. The experimental results show that both emulsions could significantly improve the compressive strength of treated sand and could withstand the changes in temperature of the Kerqin Sandy Land. However, different effects were exhibited in promoting the growth of microbes, in facilitating the accumulation of organic fertilizer and soluble salt, and in increasing the crop yield. All of the differences are attributed to their different molecular chain structures. These findings suggest that the structure of a polymeric emulsion should be the first consideration for the materials used in ecological sand-fixing, and ecological sand-fixing is a successful method for the stabilization of sandy land and the restoration of desertified land in semiarid regions.