CN117143297B - Starch-based grafted six-carbon polyether water reducer synthesized by low-temperature method and preparation method thereof - Google Patents
Starch-based grafted six-carbon polyether water reducer synthesized by low-temperature method and preparation method thereof Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 102
- 229920002472 Starch Polymers 0.000 title claims abstract description 70
- 239000008107 starch Substances 0.000 title claims abstract description 70
- 235000019698 starch Nutrition 0.000 title claims abstract description 70
- 239000003638 chemical reducing agent Substances 0.000 title claims abstract description 53
- 239000004721 Polyphenylene oxide Substances 0.000 title claims abstract description 36
- 229920000570 polyether Polymers 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 14
- 238000006243 chemical reaction Methods 0.000 claims abstract description 23
- 239000000178 monomer Substances 0.000 claims abstract description 23
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims abstract description 21
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000000243 solution Substances 0.000 claims description 17
- 239000008367 deionised water Substances 0.000 claims description 13
- 229910021641 deionized water Inorganic materials 0.000 claims description 13
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 11
- 235000013336 milk Nutrition 0.000 claims description 9
- 239000008267 milk Substances 0.000 claims description 9
- 210000004080 milk Anatomy 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 7
- 239000011790 ferrous sulphate Substances 0.000 claims description 7
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 7
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 7
- 230000002194 synthesizing effect Effects 0.000 claims description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 claims description 6
- LYCAIKOWRPUZTN-UHFFFAOYSA-N ethylene glycol Natural products OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 6
- 239000003999 initiator Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 230000007935 neutral effect Effects 0.000 claims description 6
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 6
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 5
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- -1 4-hydroxybutyl vinyl Chemical group 0.000 claims description 3
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 3
- 229920002554 vinyl polymer Polymers 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 2
- 238000000605 extraction Methods 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 238000000967 suction filtration Methods 0.000 claims description 2
- 238000001291 vacuum drying Methods 0.000 claims description 2
- 230000000379 polymerizing effect Effects 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 23
- 230000001603 reducing effect Effects 0.000 abstract description 13
- 230000000694 effects Effects 0.000 abstract description 7
- 239000004567 concrete Substances 0.000 description 28
- 238000012360 testing method Methods 0.000 description 24
- 239000004568 cement Substances 0.000 description 14
- 239000002245 particle Substances 0.000 description 9
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 5
- 238000010998 test method Methods 0.000 description 5
- 230000000740 bleeding effect Effects 0.000 description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 4
- 239000013558 reference substance Substances 0.000 description 4
- ZZZCUOFIHGPKAK-UHFFFAOYSA-N D-erythro-ascorbic acid Natural products OCC1OC(=O)C(O)=C1O ZZZCUOFIHGPKAK-UHFFFAOYSA-N 0.000 description 3
- 229930003268 Vitamin C Natural products 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000004575 stone Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 235000019154 vitamin C Nutrition 0.000 description 3
- 239000011718 vitamin C Substances 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- DKIDEFUBRARXTE-UHFFFAOYSA-N 3-mercaptopropanoic acid Chemical compound OC(=O)CCS DKIDEFUBRARXTE-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 150000004645 aluminates Chemical class 0.000 description 2
- 125000000129 anionic group Chemical group 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 239000011083 cement mortar Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 125000002791 glucosyl group Chemical group C1([C@H](O)[C@@H](O)[C@H](O)[C@H](O1)CO)* 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 238000010526 radical polymerization reaction Methods 0.000 description 2
- 150000003254 radicals Chemical class 0.000 description 2
- 235000011121 sodium hydroxide Nutrition 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 229920000881 Modified starch Polymers 0.000 description 1
- 239000004368 Modified starch Substances 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 125000002843 carboxylic acid group Chemical group 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000007385 chemical modification Methods 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000004185 ester group Chemical group 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 150000004676 glycans Chemical class 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 235000019426 modified starch Nutrition 0.000 description 1
- 150000002790 naphthalenes Chemical class 0.000 description 1
- 239000002777 nucleoside Chemical group 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229920005646 polycarboxylate Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- IIACRCGMVDHOTQ-UHFFFAOYSA-N sulfamic acid Chemical class NS(O)(=O)=O IIACRCGMVDHOTQ-UHFFFAOYSA-N 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
- C08F290/08—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated side groups
- C08F290/10—Polymers provided for in subclass C08B
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2688—Copolymers containing at least three different monomers
- C04B24/2694—Copolymers containing at least three different monomers containing polyether side chains
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
- C08F283/06—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals
- C08F283/065—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals on to unsaturated polyethers, polyoxymethylenes or polyacetals
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/302—Water reducers
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Macromonomer-Based Addition Polymer (AREA)
Abstract
The invention discloses a starch-based grafted six-carbon polyether water reducer synthesized by a low-temperature method and a preparation method thereof, wherein a starch-based functional macromonomer is taken as a framework, acrylic acid and polyether monomers are polymerized to form branched chains, dry starch is acidolyzed in the preparation process, functional starch is prepared, and the branched chains are grafted to obtain the water reducer with stronger water reducing performance and a certain degree of slow release and slump retaining effects, so that the applicability is stronger, the material proportion and the reaction condition in the preparation process are more scientific, and the reaction is more complete.
Description
Technical Field
The invention belongs to the technical field of building materials, relates to a building material, and in particular relates to a starch-based grafted six-carbon polyether water reducer synthesized by a low-temperature method and a preparation method thereof.
Background
With the rapid development of the construction industry, the cement concrete market is in short supply. After the water reducer is mixed into the concrete mixture, the anionic positioning groups on the molecules of the water reducer are adsorbed on the surfaces of cement particles, so that the cement particles are charged in the same kind, electrostatic repulsion is generated, and a wetting and lubricating effect is generated on the cement particles, so that the cement particles are more dispersed, the hydration efficiency is improved, the mixing water consumption is reduced, and the working performance of the concrete is improved. So the demand of people for water reducing agent is increasing with the development of the building industry.
At present, the water reducing agent mainly comprises polycarboxylic acid series, naphthalene series, aliphatic series, sulfamate series and the like, and is prepared from chemical raw materials such as petrochemical industry, coal chemical industry and the like, and the water reducing agent releases harmful substances in the preparation process, is easy to cause to the environment and has poor degradability. Therefore, the water reducer with more environment-friendly technology, more environment-friendly raw materials and better performance needs to be researched.
Starch is a renewable resource of biomass, and has the advantages of complete degradability, no pollution to the environment, low price and the like. The starch is polysaccharide with a plurality of glucose units connected into a long chain through glycosidic bonds, is a high polymer of glucose, has active hydroxyl and nucleoside bonds in the molecular structure, and can be used for introducing anionic groups through chemical modification to prepare the environment-friendly water reducer.
The invention provides a low-temperature method for synthesizing a starch-based grafted six-carbon polyether water reducer and a preparation method thereof, wherein a modified starch-based macromonomer is used as a main chain, and the used raw materials and process have no pollution to the environment.
Disclosure of Invention
The invention aims to provide the water reducer which is environment-friendly and degradable in used materials, simple in process, free of pollution and good in performance.
In order to achieve the aim, the technical scheme adopted by the invention is that the starch-based grafted six-carbon polyether water reducer is synthesized by a low-temperature method, and the key point is that the water reducer has the following structure:
the structure takes a starch-based functional macromonomer as a framework, and acrylic acid and polyether monomers are polymerized to form branched chains.
Further, the polyether monomer is ethylene glycol vinyl polyoxyethylene ether or 4-hydroxybutyl vinyl polyoxyethylene ether, and the weight average molecular weight of the polyether monomer is 2500-3500.
Further, the weight average molecular weight of the water reducing agent is 80000 to 100000.
Further, the molar ratio of acrylic acid to polyether monomer acid ether is 4.0-4.5: 1.
the preparation method of the starch-based grafted six-carbon polyether water reducer synthesized by a low-temperature method is used for preparing the starch-based grafted six-carbon polyether water reducer synthesized by the low-temperature method, and is characterized by comprising the following steps of:
s1, preparation of acidolysis starch: adding dry starch into deionized water to prepare starch milk with the weight percent of 35-40%, stirring for 30min in a water bath with the temperature of 40+/-2 ℃, dripping sulfuric acid solution with the weight percent of 8-12% of the dry starch, and continuously stirring for 5-7 h; after the reaction is finished, the mixture is adjusted to be neutral, and acidolysis starch is obtained after suction filtration, washing and drying;
s2, preparation of starch-based functional macromonomer with unsaturated double bond: adding 28-32 parts by weight of acidolysis starch prepared in the step S1 into deionized water to prepare starch milk with the water content of 10% -15%, uniformly mixing the starch milk with 2.0-2.5 parts by weight of maleic anhydride and 0.1-0.2 part by weight of hydroquinone, then placing the mixture into a dry pot with a cover, reacting for 3.5 h-4.5 hours in a vacuum electric furnace at the temperature of 95-105 ℃, and extracting and drying to obtain a starch-based functional macromonomer with unsaturated double bonds;
and S3, adding 350-360 parts by mass of polyether monomer into a reaction kettle, adding deionized water until the monomer can be partially dissolved, adding 0.8-1.2 parts by mass of ferrous sulfate, 8.0-10.0 parts by mass of acrylic acid and 15-20 parts by mass of starch-based functional macromonomer with unsaturated double bonds, adding 5.5-6.0 parts of initiator at the temperature of 5-10 ℃, uniformly stirring, adopting a continuous dropping method, simultaneously dropwise adding 4.0-4.5 parts by mass of the mixed solution of the starch-based functional macromonomer prepared in the step S2 and 26-29 parts by mass of acrylic acid, controlling the dropwise adding time to be 60-80 min, reacting for 50-60 min at constant temperature after the dropwise adding, adjusting the pH to be neutral by using liquid alkali, and supplementing water to obtain the water reducer with the solid content of 40%.
Further, the concentration of the concentrated sulfuric acid in S1 is 70%.
Further, the extraction in S2 above was performed three times with acetone as a solvent, and the extract was dried in a vacuum oven at 50 ℃ for 24 hours.
Furthermore, the initiator in the step S3 is hydrogen peroxide.
The beneficial effects of the invention are as follows:
(1) The water reducer disclosed by the invention has the advantages that the effect and performance of the water reducer are comprehensively improved due to the self structure:
researches show that the common starch has high polymerization degree, but the grafted unsaturated acid liquid can not be effectively adsorbed, the invention prepares the functional starch macromonomer with unsaturated double bonds by acidolysis and modification through the natural structure of the starch, and the main chain formed by the functional starch macromonomer has better adsorption effect.
The side chain of the invention is mainly composed of acrylic acid and polyether monomer side chains, a large number of hydroxyl groups and carboxylic acid groups in the water reducer are hydrophilic groups, thereby improving electrostatic adsorption and dispersion performance, and the carboxyl has strong complexing ability to metal ions and synergistic adsorption to particles with positive charges in concrete; the water reducer has the ester group, can further release carboxyl under alkaline condition, plays a secondary dispersion role, achieves a certain degree of slow release effect, and improves slump retaining performance to a certain degree; the polyether monomer structure provides a side chain containing polyether groups, a water film layer can be formed, the size of the provided space repulsive force is a key for influencing the water reducing capacity of the water film layer, the thickness of the water film layer can be effectively increased, the space repulsive force is improved, and finally the water reducing capacity can be effectively improved.
(2) In the preparation process of the invention, vitamin C is added in the polymerization reaction, and forms an oxidation-reduction system with hydrogen peroxide, so that oxygen free radicals can be prevented from being generated in the reaction system, the smooth proceeding of the free radical polymerization reaction is ensured, and the reaction is more sufficient.
(3) In the preparation process of the invention, functional starch, acrylic acid and polyether monomer are added in the preparation of the base material, so that the concentration of the starch and the acrylic acid in a pre-reaction system can be increased, ferrous sulfate plays an auxiliary catalysis role, and when hydrogen peroxide serving as an initiator begins to be dripped, free radicals are generated to initiate polymerization of the starch, the acrylic acid and the polyether monomer, and the polymerization degree of the starch and the acrylic acid on a single molecular chain can be increased.
Drawings
FIG. 1 is a schematic illustration of a reaction for preparing a starch-based functional macromonomer having an unsaturated double bond.
FIG. 2 is a schematic diagram of the structure of a starch-based functional macromonomer with an unsaturated double bond.
FIG. 3 is a schematic diagram of the structure of the water reducer of the invention.
In the figure, 1 is glucose residue in starch, 2 is double bond group, 3 is acrylic acid polymerization branched chain, and 4 is polyether monomer branched chain.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples, and the process is carried out according to the conventional conditions; the reagents or apparatus used were not specific to the manufacturer and were all commercially available conventional products, wherein EPEG represents ethylene glycol vinyl polyoxyethylene ether and VPEG represents 4-hydroxybutyl vinyl polyoxyethylene ether.
The following is a description for convenience, and the material amounts are calculated in parts by mass.
Example 1
The preparation of the acid-base starch is carried out according to the following steps, the material consumption and the reaction conditions in table 1:
(1) Placing dry starch into a three-neck flask, adding deionized water to prepare starch milk with a certain concentration, carrying out water bath in a water bath kettle at 40+/-2 ℃ and stirring for 30min;
(2) Diluting concentrated sulfuric acid with deionized water to obtain 70wt% sulfuric acid solution, adding dropwise a certain proportion of the sulfuric acid solution into the starch milk, stirring for reaction, and adding 1mol.L after the reaction is completed -1 Adjusting the reaction liquid to be neutral by sodium hydroxide solution;
(3) Filtering with a Buchner funnel, washing with deionized water for 3 times, and drying the obtained material at constant temperature in a drying oven at 45 ℃ for 10 hours to obtain acidolysis starch, wherein the sample number is expressed AS AS.
Table 1: material ratio and reaction Condition summary Table of example one
Example two
The preparation of the starch macromonomer with unsaturated double bonds was carried out according to the following steps and the material amounts and reaction conditions of Table 2:
(1) Weighing Acidolysis Starch (AS) prepared in the first embodiment, and adding a proper amount of deionized water to prepare starch milk with a certain water content;
(2) Adding maleic anhydride and hydroquinone according to the material dosage of the table 2, uniformly mixing in a stirrer, then placing in a crucible with a cover, and reacting in a vacuum electric furnace;
(3) Extracting the obtained material with acetone for three times, and drying the extract in a vacuum drying oven at 50 ℃ for 24 hours to obtain the starch macromonomer with unsaturated double bonds, which is called as functional starch for short, wherein the weight average molecular weight is 2000-20000.
Table 2: material ratio and reaction condition summary table of example two
Example III
The preparation of the water reducer is carried out according to the following steps, the material consumption and the reaction conditions in Table 3:
(1) Preparation of a mixture (A solution) of functional starch and acrylic acid: weighing a certain amount of functional starch and acrylic acid, and adding deionized water to prepare a solution A with a certain mass concentration for later use;
(2) Preparation of vitamin C and mercaptopropionic acid mixed solution (B solution): weighing a certain amount of vitamin C and mercaptopropionic acid, and adding deionized water to prepare a solution B with a certain mass concentration for later use;
(3) Polyether monomer primer preparation: adding a certain amount of deionized water, polyether monomer, acrylic acid and ferrous sulfate into a reaction kettle, wherein the polyether monomer is partially dissolved, the added ferrous sulfate is ferrous sulfate solution with the mass concentration of 1%, and the added mass part is the mass part of ferrous sulfate;
(4) Free radical polymerization: adding initiator hydrogen peroxide into the base material, directly purchasing the hydrogen peroxide, controlling the reaction temperature, uniformly stirring, dropwise adding the solution A and the solution B by adopting a continuous dropwise adding method, controlling the dropwise adding time, and performing constant-temperature reaction after the dropwise adding is finished;
(5) After the reaction is finished, adding liquid caustic soda with the concentration of about 32% to adjust the pH value to be neutral, and supplementing water to obtain water reducer samples 1-6 with the solid content of 40%.
Table 3-1: material ratio and reaction condition summary table 1 of example three
Table 3-2: material ratio and reaction condition summary table 2 of example three
The experimental conditions and the material ratios of the reference example I and the reference example II are as follows:
comparative example one
The experimental conditions and the material ratios of the third reference example No. 1 are different in that in the third step, acrylic acid is not added in the preparation process of the polyether monomer primer, the amount of acrylic acid in the solution A is adjusted, and the specific material ratios are shown in Table 4, so that a control 1 is prepared.
Comparative example two
Step three reference example No. 1, except that no functional starch was added in the preparation of solution a, and reference was made to table 4 for the material ratios, to prepare control 2.
Comparative example three
Step three, refer to the experimental conditions of example three serial number 1, except that no acrylic acid is added in the preparation process of the polyether monomer primer, no functional starch is added in the preparation of the solution A, the proportion of each material is adjusted, and the material proportion is shown in Table 4, so that a control 3 is prepared.
Comparative example four
The commercial normal polycarboxylate water reducer was control 4.
Table 4: material proportion summary table of comparative example
Test examples
In the first to sixth tests, the concrete to be tested and the reference concrete were prepared in the same proportions of cement, sand and stone as follows: the cement dosage is 360kg/m 3 The minimum water consumption when the initial slump of the reference concrete and the tested concrete reaches 210mm is taken as the water consumption, the water consumption comprises the water reducing agent and the water content in the sand and stone materials, the water reducing agent mixing amount is 0.2%, and the results of the test I to the test six are shown in the table 5.
1. Clean pulp fluidity test
Samples and controls were tested according to the methods described in GB/T8076-2016 concrete admixture Specification and GB/T8077-2012 concrete admixture homogeneity test method 13 Cement paste fluidity.
2. Water reduction rate test
Samples and controls were tested according to the methods described in GB/T8076-2016 concrete admixture Specification and GB/T8077-2012 concrete admixture homogeneity test method 14 cement mortar Water reduction Rate.
3. Bleeding Rate ratio test
Samples and controls were tested according to the methods described in GB/T8076-2016 concrete admixture Specification and GB/T50080-2016 Standard for Performance test methods for common concrete mixtures "12 bleeding test".
4. Slump, 1 hour slump was tested by variable test
Samples and controls were tested according to the methods described in GB/T8076-2016 concrete admixture Specification and GB/T50080-2016 common concrete mix Performance test method Standard, 4 slump test and slump loss over time test.
5. Compressive Strength test
Samples and controls were tested according to the methods described in GB/T8076-2016 concrete admixture Specification and GB/T50081-2019 concrete physical mechanical property test method Standard "5 compressive Strength test".
6. Shrinkage ratio test
Samples and controls were tested according to the methods described in GB/T8076-2016 concrete admixture Specification and GB/T50082-2009 ordinary concrete Long-term Performance and durability test method "8 shrinkage test".
7. Water reducing rate test of water reducing agent under different mud content
Under the condition that the proportions of cement, sand and stone used in the tested concrete and the reference concrete are the same, the mud content is controlled to be 1%, 3%, 5% and 9%, the water reducer is selected from a sample 3 and a reference substance 1-4 prepared according to the embodiment 2, the mixing amount is 0.2%, and the test is carried out according to the method described in GB/T8076-2016 concrete additive Specification and GB/T8077-2012 concrete additive homogeneity test method 14 cement mortar water reduction rate, and the test results are shown in Table 6.
Test example results and analysis:
table 5: test results of test one to test six
From the results in table 5, the following conclusions can be drawn:
the water reducer sample has strong water reducing effect, is more beneficial to improving the dispersibility and the fluidity of concrete, and is generated because the carboxyl groups play an important role in the invention, the surfaces of cement particles are positively charged due to aluminate, silicate is negatively charged, and when the water reducer is added into cement, the negatively charged carboxyl groups of the water reducer are adsorbed to the aluminate on the surfaces of the cement particles, so that electrostatic repulsion and steric hindrance effects are generated among the cement particles, the cement particles can be dispersed, and the dispersibility and the fluidity are improved.
Secondly, the average water reduction rate of the water reducer sample can reach 33.7%, the average water reduction rate of the reference substances 1-3 reaches 28.8%, and the commercial reference substance 4 is only 26.5%, so that the water reduction effect of the water reducer is obviously improved.
Thirdly, the average initial slump of the water reducer sample is 173.8mm, the 1h average slump is 162.5mm, the average initial slump of the reference products is 185mm, the 1h average slump is 176.7mm, the initial slump of the commercially available common polycarboxylic acid water reducer is 200mm, and the 1h slump is 180mm, so that the slump retaining performance of the water reducer sample is higher than that of the reference products, and the water reducer is beneficial to improving the slump retaining effect of the water reducer and can meet the design requirements of concrete projects with different slumps.
Fourth, the compressive strength of the water reducer sample of the invention is higher than that of the control group, and the compressive strength of the control group is obviously reduced in the ratio of 7d to 28d, which proves that the water reducer is helpful for improving the compressive capacity of concrete.
In addition, no bleeding phenomenon occurs in each group of samples, the bleeding phenomenon only occurs slightly in each group of control products in the test, and the control products have better shrinkage reducing effect compared with the commercial control products.
Table 6: test result of water reducing rate of water reducer under seven-different mud content
As can be seen from the results in table 6, under the condition of different mud contents, the water reducing effect of each sample and the control product is reduced along with the increase of the mud content, but the water reducing rate of the sample can still be maintained to be more than 20% when the mud content is 9%, and the water reducing rate of the control products 1-3 can also be maintained to be more than 20% when the mud content is 5%, but the water reducing effect is obviously reduced when the mud content is increased to 9%; the water reducing rate of the commercial common reference substance is reduced to below 20% when the mud content is 5%, which shows that the invention has stronger applicability to the concrete with high mud content and more stable water reducing effect.
Claims (6)
1. Synthesizing a starch-based grafted six-carbon polyether water reducer by a low-temperature method, taking an acidolysis starch-based functional macromonomer as a framework, and polymerizing acrylic acid and polyether monomers into branched chains, wherein the weight average molecular weight of the water reducer is 80000-100000;
the method comprises the following steps:
s1, preparation of acidolysis starch: adding dry starch into deionized water to prepare starch milk with the weight percent of 35-40%, stirring for 30min in a water bath with the temperature of 40+/-2 ℃, dripping sulfuric acid solution with the weight percent of 8-12% of the dry starch, and continuously stirring for 5-7 h; after the reaction is finished, the mixture is adjusted to be neutral, and acidolysis starch is obtained after suction filtration, washing and drying;
s2, preparation of starch-based functional macromonomer with unsaturated double bond: adding 28-32 parts by weight of acidolysis starch prepared in the step S1 into deionized water to prepare starch milk with the water content of 10% -15%, uniformly mixing the starch milk with 2.0-2.5 parts by weight of maleic anhydride and 0.1-0.2 part by weight of hydroquinone, then placing the mixture into a dry pot with a cover, reacting for 3.5 h-4.5 hours in a vacuum electric furnace at the temperature of 95-105 ℃, and extracting and drying to obtain a starch-based functional macromonomer with unsaturated double bonds;
and S3, adding 350-360 parts by mass of polyether monomer into a reaction kettle, adding deionized water until the monomer can be partially dissolved, adding 0.8-1.2 parts by mass of ferrous sulfate, 8.0-10.0 parts by mass of acrylic acid and 15-20 parts by mass of starch-based functional macromonomer with unsaturated double bonds, adding 5.5-6.0 parts of initiator at the temperature of 5-10 ℃, uniformly stirring, adopting a continuous dropping method, simultaneously dropwise adding 4.0-4.5 parts by mass of the mixed solution of the starch-based functional macromonomer prepared in the step S2 and 26-29 parts by mass of acrylic acid, controlling the dropwise adding time to be 60-80 min, reacting for 50-60 min at constant temperature after the dropwise adding, adjusting the pH to be neutral by using liquid alkali, and supplementing water to obtain the water reducer with the solid content of 40%.
2. The low-temperature method for synthesizing the starch-based grafted six-carbon polyether water reducer is characterized in that the polyether monomer is ethylene glycol vinyl polyoxyethylene ether or 4-hydroxybutyl vinyl polyoxyethylene ether, and the weight average molecular weight of the polyether monomer is 2500-3500.
3. The low-temperature method for synthesizing the starch-based grafted six-carbon polyether water reducer is characterized in that the molar ratio of acrylic acid to polyether monomer acid ether is 4.0-4.5: 1.
4. the low-temperature method for synthesizing the starch-based grafted six-carbon polyether water reducer is characterized in that the concentration of concentrated sulfuric acid in S1 is 70%.
5. The method for synthesizing the starch-based grafted six-carbon polyether water reducer according to claim 1, wherein the extraction in the step S2 is performed three times by using acetone as a solvent, and the extract is dried in a vacuum drying oven at 50 ℃ for 24 hours.
6. The low-temperature method for synthesizing the starch-based grafted six-carbon polyether water reducer is characterized in that the initiator in the step S3 is hydrogen peroxide.
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| CN112608067A (en) * | 2021-03-05 | 2021-04-06 | 建研建材有限公司 | Method for preparing starch-based high-performance water reducing agent and product thereof |
| CN116496454A (en) * | 2023-06-30 | 2023-07-28 | 河北合众建材有限公司 | Low-temperature method for synthesizing multi-branched slump retaining polyether water reducer and preparation method thereof |
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| CN112608067A (en) * | 2021-03-05 | 2021-04-06 | 建研建材有限公司 | Method for preparing starch-based high-performance water reducing agent and product thereof |
| CN116496454A (en) * | 2023-06-30 | 2023-07-28 | 河北合众建材有限公司 | Low-temperature method for synthesizing multi-branched slump retaining polyether water reducer and preparation method thereof |
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