Chitosan oligosaccharide graft modified polycarboxylate water reducer and preparation method thereof

Abstract

The invention discloses a chitosan oligosaccharide graft modified polycarboxylate water reducer and a preparation method thereof. The steps of the method are as follows: 1) preparing chitosan oligosaccharide amidated macromonomer, adding chitosan oligosaccharide, maleic acid The acid anhydride is placed in a polar solvent at a molar ratio of 1:1.02~1.1, and a catalyst is added at 85~95°C to stir for 3~4 hours, then washed and dried to obtain a powdery chitosan oligosaccharide amidated macromonomer; 2) Preparation of water reducing As an agent, methallyl polyoxyethylene ether and chitosan oligosaccharide amidated macromonomer are subjected to aqueous radical polymerization to obtain chitosan oligosaccharide grafted modified polycarboxylate water reducer. The chitosan oligosaccharide amidated macromonomer directly participates in the polymerization through the carbon-carbon double bond, and the polymerization activity is high. The side chain of the chitosan oligosaccharide can greatly improve the viscosity-increasing and water-retaining properties of the water-reducing agent, and can further enhance the dispersibility of the water-reducing agent. , In addition, it interacts with the long side chain of polyether, making the hydration film formed on the surface of cement particles more stable, and the loss of slump over time is smaller.

Description

technical field [0001] The invention relates to the technical field of concrete, in particular to a chitosan oligosaccharide graft modified polycarboxylate water reducer and a preparation method thereof. Background technique [0002] As an indispensable component in concrete, polycarboxylate superplasticizer has low dosage and good dispersion, which can significantly improve the working performance of concrete, improve the strength and durability of concrete, and is environmentally friendly. However, in recent years, the quality problems of cement, mineral admixtures, coarse aggregates, and fine aggregates have been serious. In addition, there are many types of cement in my country and various engineering mix ratios, making it difficult for existing polycarboxylate superplasticizers to meet new requirements. Mixed concrete requires cohesion and water retention, and problems such as bleeding, segregation, poor workability, and rapid collapse are prone to occur. In order to en...

AI Technical Summary

Problems solved by technology

However, there is no carbon-carbon double bond in the molecular structure of the first two. Although hydroxyl groups can also be initiated to form free radicals to participate in copolymerization, the polymerization activity is far inferior to carbon-carbon double bonds, and the polymerization conversion rate is low.

In addition, chitosan and polysaccharides containing hydroxyl and carboxyl groups (such as Wenlun gum, Dingyou gum and Sanzan gum) have high molecular weight, poor water solubility, and low grafting rate, while rhamnose has a low molecular weight and a low introduction amount. When it is less, the effect of viscosity increase and water retention is not significant, otherwise it will affect the adsorption and dispersion of water reducer

Finally, the unsaturated carboxylate monomer of cellulose ether is connected to the main chain of the polycarboxylate superplasticizer molecule by the ester group, and the ester group is easily hydrolyzed in the alkaline environment of concrete. The release of cellulose ether reduces the side chain of cellulose ether in the polycarboxylic acid molecule and reduces the viscosity-increasing and water-retaining effect

Images