Hauv kev sivHydroxypropyl methyl cellulose HPMC, peb feem ntau pom tias nws yog qhov yooj yim faib ua ob hom: tam sim ntawd thiab qeeb dissolution. Cia peb nkag siab qhov sib txawv ntawm kev tawg sai thiab qeeb qeeb ntawm hydroxypropyl methyl cellulose.
Instant HPMC yog hais txog kev siv tus neeg sawv cev sib txuas rau saum npoo ntawm cov txheej txheem tsim khoom, kom HPMC tuaj yeem tawg sai sai hauv dej txias, tab sis tsis yog ib qho kev daws teeb meem tiag tiag, los ntawm kev sib xyaw ua ke, viscosity maj mam nce, uas yog, kev sib cais;
Hwj chim soluble HPMC kuj tseem hu ua cov khoom kub yaj. Thaum ntsib dej txias, nws tuaj yeem tawg sai sai hauv dej kub. Los ntawm stirring tusyees, qhov kub ntawm cov tshuaj yuav poob mus rau ib tug tej yam kub. (Qhov kub ntawm peb cov gel yog li 60 ° C), viscosity yuav tshwm sim maj mam kom txog thaum lub pob tshab thiab nplaum nplaum tsim.
Ntawm no yog qhov sib txawv ntawm kev daws tam sim thiab kev daws qeeb. Yog tias koj muaj lus nug txog qhov kev paub no, koj tuaj yeem sab laj nrog peb.
Hydroxypropyl methyl celluloseHPMCncua cov cement hydration
Ntxiv hydroxypropyl methyl cellulose rau cov cement slows nws hydration. Yog li koj paub dab tsi txog nws ua haujlwm li cas? Cia peb saib ntawm hydroxypropyl methyl cellulose kom ncua cov cement hydration. Txoj Cai.
1. Ion txav tsis meej hypothesis
Peb xav tias hydroxypropyl methyl cellulose yuav ua rau kom cov viscosity ntawm pore daws, cuam tshuam tus nqi ntawm ionic zog, thiab ncua lub hydration ntawm cement. Txawm li cas los xij, qhov qis dua viscosity cellulose ethers hauv qhov kev sim no muaj peev xwm ua kom cov cement hydration. Yog li ntawd, qhov kev xav no tsis raug. Pourchez et al. kuj tsis ntseeg qhov kev xav no. Nyob rau hauv qhov tseeb, lub sij hawm ntawm ion tsiv teb tsaws los yog tsiv teb tsaws yog luv heev, pom tau hais tias tsis sib xws rau ncua sij hawm ntawm cement hydration.
2. Alkaline degradation
Polysaccharides yooj yim degrade nyob rau hauv alkaline tej yam kev mob los tsim hydroxyl carboxylic acids uas ncua cov cement hydration. Yog li ntawd, ncua sij hawm hydration ntawm hydroxypropyl methyl cellulose yuav yog vim nws degradation nyob rau hauv alkaline cement slurries los tsim hydroxycarboxylic acids. Txawm li cas los xij, Pourchez et al. pom tias cellulose ethers tau ruaj khov nyob rau hauv alkaline tej yam kev mob, degraded tsuas yog me ntsis, thiab cov khoom degradation muaj me ntsis cuam tshuam rau kev ncua ntawm cement hydration.
3, lub adsorption
Adsorption tuaj yeem yog hydroxypropyl methyl cellulose thaiv cov cement hydration yog vim li cas ntau cov organic additives yuav adsorbed ntawm cov cement hais thiab cov khoom hydration, tiv thaiv kev tawg ntawm cov cement hais thiab crystallization ntawm hydration cov khoom, thiaj li mus ncua lub hydration thiab condensation ntawm cement. Pourchez et al. pom tias cellulose ethers tau yooj yim adsorbed rau ntawm qhov chaw ntawm hydration khoom xws li calcium hydroxide, CSH gel thiab calcium aluminate hydrate, tab sis tsis tau yooj yim adsorbed los ntawm ettringite thiab unhydrated theem. Ntxiv mus, nyob rau hauv cov ntaub ntawv ntawm cellulose ether, lub peev xwm adsorption ntawm HEC muaj zog dua li o ntawm MC. Cov ntsiab lus qis ntawm hydroxyethyl hauv HEC lossis hydroxypropyl hauvHPMC, lub zog muaj peev xwm adsorption: raws li cov khoom siv dej, lub peev xwm adsorption ntawm calcium hydroxide muaj zog dua li ntawm CSH. Kev soj ntsuam ntxiv kuj tseem qhia tau tias qhov muaj peev xwm adsorption ntawm cov khoom siv dej thiab cov cellulose ether cuam tshuam nrog kev ncua ntawm cov cement hydration: qhov muaj zog ntawm cov adsorption, qhov pom tseeb dua qhov ncua sij hawm, tab sis ettringite adsorption ntawm cellulose ether tsis muaj zog, tab sis nws tsim, tab sis qhov no yog qeeb qeeb. cellulose ether ntawm tricalcium silicate thiab nws cov hydration cov khoom muaj ib tug muaj zog adsorption, nws obviously ncua lub hydration txheej txheem ntawm silicate theem, lub adsorption tus nqi ntawm ettringite yog tsawg heev, tab sis ncua sij hawm ettringite tsim yog pom tseeb, vim ncua sij hawm ettringite tsim yog cuam tshuam los ntawm Ca 2 + tshuav nyiaj li cas ntawm cov tshuaj, nws yog ib qho yooj yim mus use. Silicate hydration lig txuas ntxiv mus.
Cov no yog hydroxypropyl methyl cellulose ncua cement hydration txoj cai. Peb cia siab tias qhov kev paub no yuav ua rau txhua tus neeg nkag siab tias cov khoom ua haujlwm li cas thiab siv nws zoo dua.
Post lub sij hawm: Apr-26-2024