Yuav ua li cas npaj polycarboxylic superplasticizer?

Raws li cov txheej txheem ntawm kev ua ntawm superplasticizers, hydrophilic-lipophilic tshuav nyiaj li cas (HLB) ntawm cov molecules tuaj yeem hloov kho los ntawm kev tswj qhov sib piv ntawm cov kua qaub rau ester. Los ntawm kev xav ntawm kev tsim qauv molecular, tshiab polycarboxylate superplasticizers tuaj yeem ua ke. Cov qauv molecular tsim ntawm high-performance superplasticizers nyiam ua kom paub ntau cov polar functional pawg xws li carboxyl pawg, sulfonic acid pawg, thiab polyethylene oxide pawg rau hauv cov saw tseem ceeb los yog sab chains ntawm cov molecules, muab cov molecule ib lub zuag-zoo li qauv. Cov polarity piv ntawm cov polar thiab non-polar pawg yog hloov kho kom zoo dispersion zog, nrog rau cov ntsiab lus ntawm pawg tsis-polar feem ntau tsis tshaj 30%. Los ntawm kev kho qhov hnyav molecular ntawm cov polymer, cov dej-txo muaj peev xwm thiab ruaj khov ntawm cov khoom yog txhim kho. Kho qhov hnyav ntawm cov saw hlau molecular nce steric hindrance thiab txhim kho dispersibility thiab tuav kev ua tau zoo. Raws li cov ntaub ntawv, cov monomers siv los ua ke polycarboxylate superplasticizers feem ntau suav nrog plaub hom:

1. Unsaturated acids - txiv neej anhydride, maleic acid, acrylic acid, methacrylic acid;
2. Polychain olefin tshuaj - polyolefins thiab lawv cov derivatives uas muaj cov pab pawg sib txawv;
3. Polystyrene sulfonates los yog esters;
4. (Meth) acrylate ntsev, esters, los yog amides.

Cov txheej txheem synthesis muaj xws li:

1. Ua ntej, ua ke cov monomers xav tau, xws li reactive polymeric monomers. Piv txwv li, alkylphenols lossis lauryl cawv tuaj yeem hnov ​​​​mob nrog allyl cawv los npaj allylphenol lossis polyethylene glycol ether carboxylates, lossis siv ethylene oxide, polyethylene glycol, thiab lwm yam, los ua ke polychain olefin tshuaj - polyolefins, ethers, cawv, sulfonates, lossis polystyrene. . Hauv theem thib ob, qhia cov neeg ua haujlwm tsis zoo xws li pawg carboxyl, pawg sulfonic acid, thiab polymer sab chains nrog dej zoo affinity rau hauv cov roj lossis cov kuab tshuaj. Cov khoom kawg nrog cov khoom xav tau yog tau. Qhov tseeb polycarboxylate superplasticizers tuaj yeem yog binary, ternary, lossis quaternary copolymer.
2. Cov khoom siv raw: acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, sodium vinyl sulfonate, sodium 2-propenyl sulfonate, 2-acrylamido-2-methylpropane sulfonate (AMPS) , monohydroxy polyethylene glycol ethers (PEG 600, PEG 1000, PEG 1500), sodium persulfate, ammonium persulfate, hydrogen peroxide, thiab lwm yam. Synthesis method: Raws li kev tsim qauv molecular, sib tov ntau yam monomers hauv qhov xav tau sib piv, ntxiv rau lawv mus rau cov tshuaj tiv thaiv cov hlab ntsha nrog rau cov khoom hnyav molecular thiab cov kuab tshuaj, hloov cov huab cua nyob rau hauv cov tshuaj tiv thaiv cov hlab ntsha nrog nitrogen gas, thiab kub rau 75-90 degree. nyob rau hauv kev tiv thaiv nitrogen. Ib txhij, ntxiv cov tshuaj uas muaj cov neeg pib thiab lwm cov copolymer monomers, thiab polymerize rau 6-8 teev nyob rau hauv stirring. Tom qab polymerization tiav, cov kua nplaum copolymer tau txais. Kho cov pH mus rau nruab nrab nrog dilute alkali tov thiab kho cov ntsiab lus khoom mus txog 30%.
3. Cov qauv molecular ntawm polycarboxylate superplasticizers yog comb-zoo li, nrog hydrophilic active pab pawg nyob rau sab chains thiab ntev chains nrog ib tug loj tus naj npawb ntawm cov pab pawg neeg. Raws li lub hauv paus ntsiab lus no, peb cov monomers sib txawv raug xaiv: maleic anhydride ua ib qho tsis muaj kua qaub, vinyl sulfonate ua cov saw hydrocarbon, thiab methyl acrylate ua ib qho nonionic monomer. Cov ntaub ntawv no yog purified, thiab cov pib siv yog K2SO4. Lub copolymerization yog nqa tawm nyob rau hauv ib tug plaub-caj dab ntim nrog ib tug pas ntsuas kub, xa me nyuam rov funnel, thiab reflux condenser. Distilled dej yog ntxiv, thiab cov tshuaj tiv thaiv sib tov yog rhuab nyob rau hauv stirring. Cov monomers tau ntxiv cov kauj ruam mus rau hauv qhov xau funnel nyob rau hauv cov xwm txheej reflux rau 4 teev. Cov khoom tau txais thiab nws cov flowability yog ntsuas.
4. Cov khoom siv raw: txiv neej anhydride, amide monomers, ammonium persulfate, 30% hydrogen peroxide, sodium hydroxide, thiab tshuaj-qib purity reagents. Synthesis method: Cov synthesis yog ua los ntawm cov tshuaj tiv thaiv dawb radical copolymerization uas siv cov txheej txheem sib xyaw ntawm ammonium persulfate thiab 30% hydrogen peroxide. Lub aqueous polymerization yog ua ntawm 102-110 degree rau li 8 teev, yielding lub teeb daj pob tshab kua raws li cov khoom.