Chitosan oligosaccharide graft modified polycarboxylic acid water reducing agent and preparation method of water reducing agent

A technology of graft modification and water reducing agent, which is applied in the field of concrete, can solve the problems of poor water solubility, high molecular weight, low grafting rate, etc., and achieve the effect of improving viscosity increase and water retention, high polymerization activity, and small loss over time

Active Publication Date: 2019-09-10
CCCC SHEC WUHAN PORT NEW MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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

Method used

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  • Chitosan oligosaccharide graft modified polycarboxylic acid water reducing agent and preparation method of water reducing agent
  • Chitosan oligosaccharide graft modified polycarboxylic acid water reducing agent and preparation method of water reducing agent
  • Chitosan oligosaccharide graft modified polycarboxylic acid water reducing agent and preparation method of water reducing agent

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] A kind of preparation method of chitosan oligosaccharide graft modified polycarboxylate water reducer, the steps are:

[0052] (1) Synthesis of Chitooligosaccharide Amidated Macromonomer:

[0053] Weigh chitooligosaccharide, maleic anhydride, and 4-dimethylaminopyridine successively in a molar ratio of 1:1.02:0.02;

[0054] At room temperature, dissolve chitosan and maleic anhydride with a molecular weight of 1000 and a degree of deacetylation of 90% in N,N-dimethylformamide, raise the temperature to 85°C, and add 4-dimethylaminopyridine as Catalyst, stirring reaction 3h. After the reaction is completed, the product is washed with acetone and water for 3 to 5 times respectively, placed in an oven at 45° C. and baked to constant weight to obtain a powdery chitosan oligosaccharide amidated macromonomer.

[0055] (2) Polymerization reaction:

[0056] Weigh methallyl polyoxyethylene ether, chitosan oligosaccharide amidated macromonomer, acrylic acid, 3-mercaptopropionic ...

Embodiment 2

[0061] A kind of preparation method of chitosan oligosaccharide graft modified polycarboxylate water reducer, the steps are:

[0062] (1) Synthesis of Chitooligosaccharide Amidated Macromonomer:

[0063] Weigh chitooligosaccharide, maleic anhydride, and 4-dimethylaminopyridine successively in a molar ratio of 1:1.05:0.025;

[0064] At room temperature, dissolve chitosan and maleic anhydride with a molecular weight of 1500 and a degree of deacetylation of 90% in N,N-dimethylformamide, raise the temperature to 88°C, and add 4-dimethylaminopyridine as Catalyst, stirring reaction 3h. After the reaction is completed, the product is washed with acetone and water for 3 to 5 times respectively, placed in an oven at 45° C. and baked to constant weight to obtain a powdery chitosan oligosaccharide amidated macromonomer.

[0065] (2) Polymerization reaction:

[0066] The molar ratio is 1.0:0.12:6.4:0.11:0.25:0.028 to weigh methallyl polyoxyethylene ether, chitooligosaccharide amidated ...

Embodiment 3

[0071] A kind of preparation method of chitosan oligosaccharide graft modified polycarboxylate water reducer, the steps are:

[0072] (1) Synthesis of Chitooligosaccharide Amidated Macromonomer:

[0073] Weigh chitooligosaccharide, maleic anhydride, and 4-dimethylaminopyridine successively in a molar ratio of 1:1.05:0.028;

[0074] At room temperature, dissolve chitosan and maleic anhydride with a molecular weight of 1500 and a degree of deacetylation of 92% in N,N-dimethylformamide, raise the temperature to 90°C, and add 4-dimethylaminopyridine as Catalyst, stirred and reacted for 3.5h. After the reaction is completed, the product is washed with acetone and water for 3 to 5 times respectively, placed in an oven at 45° C. and baked to constant weight to obtain a powdery chitosan oligosaccharide amidated macromonomer.

[0075] (2) Polymerization reaction:

[0076] The molar ratio is 1.0:0.14:6.7:0.14:0.3:0.03 and weighs methallyl polyoxyethylene ether, chitooligosaccharide a...

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Abstract

The invention discloses a chitosan oligosaccharide graft modified polycarboxylic acid water reducing agent and a preparation method of the water reducing agent. The method comprises the following steps: 1) preparing a chitosan oligosaccharide amidated macro-monomer, placing chitosan oligosaccharide and maleic anhydride in a molar ratio of 1:1.02-1.1 into a polar solvent, adding a catalyst at 85-95DEG C and carrying out a reaction for 3-4 h under stirring, and performing washing and oven-drying to obtain the powdery chitosan oligosaccharide amidated macro-monomer; and 2) preparing the water reducing agent, performing free radical polymerization in an aqueous solution on methyl allyl polyoxyethylene ether and the chitosan oligosaccharide amidated macro-monomer to obtain the chitosan oligosaccharide graft modified polycarboxylic acid water reducing agent. The chitosan oligosaccharide amidated macro-monomer directly participates in polymerization through a carbon-carbon double bond, and has high polymerization activity, and chitosan oligosaccharide side chains can greatly enhance viscosity-increasing water-retention properties of the water reducing agent, and can further enhance dispersion of the water reducing agent. In addition, the chitosan oligosaccharide side chains interacts with polyether long side chains, so that a hydrated film formed on the surface of cement particles ismore stable, and slump-loss is smaller over time.

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...

Claims

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Application Information

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IPC IPC(8): C04B24/32C08F251/00C08F283/06C08F220/06C04B103/30
CPCC04B24/32C04B2103/302C08F251/00C08F283/065C08F220/06
Inventor 高玉军李顺凯明阳沈尔卜王文荣
Owner CCCC SHEC WUHAN PORT NEW MATERIALS
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