Peb Cov Txheej Txheem Txheej Txheem Ntawm Niam Dej Dej Ntawm Polycarboxylic Superplasticizer

Peb Txoj Kev rau Synthesizing Polycarboxylate Superplasticizers

1. Tom qab-Polymerization Functionalization MethodTxoj kev no feem ntau yuav hloov kho cov polymers uas twb muaj lawm. Feem ntau, paub qhov hnyav molecular polycarboxylates yog grafted nrog polyethers los ntawm esterification nyob rau hauv qhov kev txiav txim ntawm ib tug catalyst ntawm kub kub, tsim graft copolymer. Txawm li cas los xij, txoj kev no tsuas yog txwv los ntawm ntau yam thiab cov ntsiab lus ntawm cov khoom muaj polycarboxylate, ua rau nws nyuaj rau kev kho qhov muaj pes tsawg leeg thiab qhov hnyav molecular. Tsis tas li ntawd, thaum npaj, kev sib raug zoo ntawm polycarboxylates thiab polyethers tsis zoo, ua rau kev ua haujlwm esterification nyuaj. Raws li esterification zuj zus, dej tsis tu ncua tso tawm, uas tuaj yeem ua rau theem sib cais.

Txheej txheem Synthesis: Siv alkoxyamine H2N (BO)-R ua cov reactant rau graft nrog polycarboxylates (qhov twg BO sawv cev rau ib pawg alkylene oxide,nyog tus lej, thiab R yog C1-C4 alkyl pawg), cov solubility ntawm polycarboxylates hauv alkoxyamine ua kom muaj kev sib xyaw ua ke zoo. Thaum lub sij hawm cov tshuaj tiv thaiv, tus nqi ntawm amine reactant feem ntau yog 10% mus rau 20% ntawm cov molar tooj ntawm -COOH pawg. Ua ntej, cov tshuaj tiv thaiv sib tov yog rhuab mus rau saum 150 degree thiab reacted rau 1.5 mus rau 3 teev. Tom qab ntawd, qhov kub thiab txias yog txo mus rau 100 degree mus rau 130 degree, thiab ib tug catalyst ntxiv rau react rau lwm 1.5 mus rau 3 teev kom tau cov khoom xav tau.

2. Nyob rau hauv Situ Polymerization thiab Grafting MethodTxoj kev no kov yeej qhov tsis txaus ntawm txoj kev ua haujlwm tom qab-polymerization los ntawm kev siv cov polyethers ua cov tshuaj tiv thaiv nruab nrab rau carboxylic acid-based unsaturated monomers. Cov txheej txheem sib xyaw ua ke polymerization thiab esterification, yog li zam kev sib raug zoo ntawm polycarboxylates thiab polyethers.

Txheej txheem Synthesis: Ib qho sib xyaw ntawm acrylic acid monomer, saw hloov tus neeg sawv cev, thiab cov pib pib maj mam ntxiv rau cov tshuaj aqueous ntawm methoxy polyethylene glycol nrog cov txheeb ze molecular hnyav ntawm 2000. Cov tshuaj tiv thaiv tshwm sim ntawm 60 degree rau 45 feeb. Tom qab ntawd qhov kub thiab txias yog nce mus rau 120 degree, thiab nyob rau hauv kev tiv thaiv nitrogen, dej yog tsis tu ncua (kwv yees li 50 feeb). Ib qho catalyst ntxiv, thiab qhov kub nce mus rau 165 degree rau 1 teev, ua rau ntxiv grafting thiab tau txais cov khoom kawg.

Thaum txoj kev no tso cai rau kev tswj cov khoom hnyav ntawm cov khoom siv polymer, cov saw tseem ceeb feem ntau tsuas yog muaj cov monomers uas muaj -COOH pawg. Txwv tsis pub, grafting yuav nyuaj. Tsis tas li ntawd, cov tshuaj tiv thaiv grafting yog cov tshuaj tiv thaiv kev sib npaug, thiab cov txheej txheem pib muaj cov dej ntau, ua rau grafting degree qis thiab nyuaj rau kev tswj. Txoj kev no yog qhov yooj yim ntawm cov txheej txheem thiab muaj cov nqi tsim khoom tsawg tab sis ua rau muaj teeb meem hauv kev tsim molecular.

3. Direct Copolymerization ntawm Polymerizable MonomersTxoj kev sib xyaw no feem ntau suav nrog kev npaj cov macromonomers nrog cov haujlwm polymerizable, xws li methoxy polyethylene glycol methacrylate. Ib qho piv txwv tshwj xeeb ntawm monomers yog tom qab sib xyaw thiab raug rau kev daws teeb meem polymerization kom tau txais cov khoom kawg. Tus yuam sij rau cov txheej txheem synthesis no yog nyob rau hauv kev npaj ntawm lub active macromonomer, uas yuav tsum tau complex sib cais thiab purification cov kauj ruam, ua rau cov nqi siab dua.

Txheej txheem Synthesis: Nyob rau hauv ib lub khob tshuaj tiv thaiv lub nkoj nruab nrog tus pas ntsuas kub, stirrer, xa me nyuam rov funnel, nitrogen inlet, thiab reflux condenser, 500 qhov chaw los ntawm qhov hnyav ntawm cov dej ntxiv. Cov tshuaj yog deoxygenated los ntawm stirring nyob rau hauv ib tug nitrogen chaw thiab ces rhuab mus rau 80 degree. Tshaj li 4 teev, cov tshuaj monomer uas muaj 250 feem ntawm cov saw luv methoxy polyethylene glycol methacrylate (EO ntxiv tus lej=4), 50 qhov chaw ntawm cov saw ntev methoxy polyethylene glycol methacrylate (EO ntxiv tus lej=23) , 200 qhov chaw ntawm methacrylic acid, 150 qhov chaw ntawm dej, thiab 13.5 qhov chaw ntawm cov saw hloov chaw (3-mercaptopropionic acid) maj mam ntxiv. Ib txhij, 40 feem ntawm 10% ammonium persulfate aqueous tov yog ntxiv. Tom qab qhov sib ntxiv ua tiav, ib qho ntxiv 10 feem ntawm 10% ammonium persulfate aqueous tov yog ntxiv rau 1 teev, thiab cov tshuaj tiv thaiv tau khaws cia rau 1 teev. Cov khoom kawg yog cov tshuaj polymer nrog qhov hnyav-qhov nruab nrab molecular hnyav ntawm 15, 000.