Applied Fundamental Research Of Polymer Modified Cement Mortar

Polymer modified cement mortar is a very important composites. As a fundamental industrial application research, comprehensive utilization of renewable resources and the convenience of construction was the target of this study. Waterborne bisphenol A epoxy resin emulsion of low epoxide number, high boiling solvent(HBS) lignin epoxy resin and its hydrophilic derivative of lignin from bamboo were synthesized. The effects of these polymers to mechanical properties of cement mortar were investigated. The phase inversion technique is one of the most effective means for preparation of polymer emulsion, almost all of polymers can be formed emulsion by using the method. The emulsifying capability of an emulsifier is a very important factor, which influence the stability and particle size of polymer emulsion. The water-based epoxy resin was prepared by the phase inversion technique using reactive emulsifier. The result showed that, the reactive emulsifier with higher emulsifying capacity could be synthesized by setting mol ratio 1/1 of epoxy resin of low epoxide number(E=0.2261mol/100g) to polyethylene glycol (Mn= 4000),using NaOH as a catalyst at 65~70℃. High boiling solvent (HBS) lignin is a renewable natural polymer with a lot of ethanol hydroxyl groups and phenol hydroxyl groups in the molecular structure, which shows better chemical activities. At 65~70℃,high boiling solvent(HBS) lignin epoxy resin was synthesized by HBS lignin in 7% NaOH solution, and hydrophilic derivative of the lignin-based epoxy resin was prepared under the similar condition. The two products were investigated by IR spectrum. Polymer modified cement mortar were prepared by water-based bisphenol A epoxy resin emulsion, high boiling solvent (HBS) lignin-based epoxy resin and its hydrophilic derivative of lignin from bamboo. The effect of stability of water-based epoxy resin emulsion, different ratio of polymer to cement and curing condition of waterborne epoxy resin emulsion, HBS lignin-base epoxy resin and its hydrophilic derivative and the mechanical properties of the polymer modified cement mortar were investigated. The composite was analyzed by SEM. The results showed that the waterborne epoxy resin emulsion with better stability modified cement mortar had better mechanical properties, and with the increasing of ratio of polymer to cement, the flexural strength of cement mortar was improved, but its compressive strength was decreased. When the ratio of polymer to cement was more than 0.12, its flexural strength and toughness were apparently improved. The result also showed that the combination of wet and dry curing condition was better than wet curing condition. The cement mortar modified by hydrophilic derivative of HBS bamboo lignin base epoxy resin, which was grafted by polyethylene glycol in molecular structure, had better mechanical properties than by HBS bamboo lignin-based epoxy resin. According to SEM analysis, the three-dimensional net structure of polymer was formed in the composite.