Hydroxypropyl methylcellulose (HPMC) yog ib qho tseem ceeb ntawm cellulose derivative. Nws yog dav siv hauv cov khoom siv hauv tsev vim nws cov dej tuav tau zoo, thickening thiab stability hauv tsev mortar.
1. Cov qauv tshuaj thiab cov yam ntxwv ntawm HPMC
HPMC yog cov khoom siv ntau yam polymer ua los ntawm kev hloov tshuaj lom neeg ntawm cov cellulose ntuj. Hauv nws cov qauv tshuaj, hydroxypropyl (-CH₂CH(OH)CH₃) thiab methyl (-CH₃) pawg hloov ib feem ntawm hydroxyl pawg (-OH) ntawm cov cellulose molecular saw, ua rau HPMC muaj dej solubility zoo thiab thickening zog.
Solubility: HPMC yog yooj yim soluble nyob rau hauv dej txias los ua ib pob tshab rau milky colloidal tov. Nws dissolves maj mam nyob rau hauv dej kub, uas yuav pab kom nws sib npaug zos nyob rau hauv lub tsev mortar.
Kev tuav dej: Cov saw hlau polymer ntawm HPMC tuaj yeem nqus dej tau zoo thiab tsim cov tshuaj viscosity colloidal, yog li txo cov dej poob.
Kev ruaj ntseg: HPMC muaj kev ruaj ntseg zoo heev thiab ua siab ntev rau qhov kub thiab pH tus nqi, uas ua rau nws ua haujlwm ruaj khov nyob rau hauv ntau yam kev tsim kho.
2. Lub luag haujlwm ntawm HPMC hauv kev tsim mortar
Ua kom dej tuav: HPMC tuaj yeem txhim kho cov dej tuav lub peev xwm ntawm lub tsev mortar, feem ntau los ntawm kev nqus dej dawb hauv mortar thiab txo cov dej evaporation thiab to.
Txhim kho kev ua haujlwm: Txij li HPMC tuaj yeem tsim ib qho kev sib cais zoo hauv lub mortar, nws tuaj yeem txhim kho cov yas thiab kev ua haujlwm ntawm cov mortar, ua rau kev tsim kho yooj yim dua.
Txuas lub sijhawm qhib: HPMC lub peev xwm khaws cov dej noo tso cai rau cov tshuaj khib kom muaj qhov sib xws uas haum rau kev tsim kho rau lub sijhawm ntev, yog li txuas ntxiv lub sijhawm qhib ntawm mortar.
3. Mechanism ntawm HPMC los txhim kho dej tuav
Lub tshuab ntawm HPMC los txhim kho cov dej tuav ntawm mortar feem ntau suav nrog cov hauv qab no:
Adsorption: Cov hydroxypropyl thiab methyl pawg ntawm HPMC molecular saw txuas nrog cov dej molecules los ntawm hydrogen bonds thiab van der Waals rog los tsim ib txheej dej ruaj khov. HPMC tuaj yeem nqus tau cov dej ntau los tsim cov gel ruaj khov. Lub xeev gel no tuaj yeem tswj tau cov dej noo siab hauv cov tshuaj khib nyiab thiab tiv thaiv kom tsis txhob muaj dej nrawm.
Viscoelastic zog: HPMC dissolves nyob rau hauv dej los tsim ib tug siab viscosity colloidal tov, uas yuav ua rau kom lub viscosity thiab rheology ntawm lub mortar. Lub siab viscosity kua theem pab txo cov kev tsiv teb tsaws ntawm cov dej, tswj cov dej tsis sib xws ntawm cov mortar, thiab txo cov dej sib cais (piv txwv li, dej ntab thiab nag lossis daus).
Kev tsim cov qauv tsim: HPMC tuaj yeem tsim cov qauv sib txuas sib txuas hauv cov dej hauv cov dej, uas yuav pab txhawm rau txhawm rau hauv dej thiab txwv tsis pub nws txav mus rau hauv mortar, yog li txhim kho cov dej tuav ntawm cov tshuaj khib nyiab. Lub network qauv ntawm HPMC tso cai rau cov mortar kom nyob twj ywm tsis tu ncua thaum lub sij hawm hardening txheej txheem, tsis txhob tawg teeb meem tshwm sim los ntawm cov dej tsis sib xws.
Colloidal barrier effect: Lub colloidal barrier tsim los ntawm HPMC nyob rau hauv lub mortar tuaj yeem tiv thaiv dej los ntawm kev tawm sab nraud. Qhov kev cuam tshuam no ua rau nws nyuaj rau cov dej kom dim ntawm lub mortar, yog li ua kom cov dej tuav ntawm lub mortar.
4. Kev siv tau zoo ntawm HPMC dej tuav
Hauv kev siv cov tswv yim, cov dej tuav ntawm HPMC muaj qhov cuam tshuam loj rau kev ua haujlwm ntawm mortar, nrog rau kev txhim kho kev ua haujlwm ntawm mortar, txo qhov kev pheej hmoo ntawm shrinkage cracking, thiab txhim kho daim ntawv cog lus. Cov teebmeem ntawm daim ntawv thov no tau tham txog hauv qab no.
Txhim kho kev ua haujlwm: Cov tshuaj colloidal tsim los ntawm HPMC hauv mortar tuaj yeem lubricate cov khoom hauv cov tshuaj khib nyiab, txhim kho kev ua haujlwm ntawm cov mortar, thiab ua kom cov txheej txheem tsim kho kom zoo dua.
Txo cov shrinkage thiab tawg: Vim HPMC tuaj yeem khaws cov dej noo hauv cov tshuaj khib nyiab, nws txo qis cov dej noo thaum lub sij hawm ziab, uas yog qhov tseem ceeb kom tsis txhob shrinkage thiab tawg ntawm mortar. Mortar uas tseem nyob sib npaug zos thaum lub sij hawm hardening txheej txheem muaj tsawg shrinkage kev nyuaj siab, yog li txo qhov muaj peev xwm ntawm cracking.
Txhim kho daim ntawv cog lus muaj zog: Qhov sib npaug ntawm cov dej noo hauv cov mortar pab txhim kho kev ua haujlwm ntawm cov tshuaj tiv thaiv hydration ntawm cov tshuaj khib nyiab, xyuas kom meej tias cov cement particles muaj dej txaus, thiab thaum kawg tsim ib daim ntawv cog lus muaj zog. HPMC tuaj yeem muab qhov chaw ntub dej mus ntev, ua rau cov cement hydration ntau dua, yog li txhim kho lub zog ntawm cov mortar.
5. Yam cuam tshuam rau HPMC ntawm lub tsev mortar
Cov dej tuav pov hwm ntawm HPMC cuam tshuam los ntawm ntau yam, suav nrog nws qhov hnyav molecular, qib ntawm kev hloov pauv, tus nqi ntxiv thiab mortar piv.
Molecular Luj: Feem ntau hais lus, qhov loj dua qhov hnyav molecular ntawm HPMC, qhov tseem ceeb dua cov dej tuav. Txawm li cas los xij, qhov hnyav dhau ntawm molecular hnyav kuj tuaj yeem ua rau txo qis hauv solubility, yog li hauv kev siv tswv yim, nws yuav tsum xaiv qhov hnyav molecular raws li cov kev xav tau tshwj xeeb.
Degree ntawm kev hloov pauv: Qib ntawm kev hloov pauv ntawm hydroxypropyl thiab methyl hauv HPMC muaj kev cuam tshuam zoo rau nws qhov kev ua tau zoo. Kev hloov pauv uas tsim nyog tuaj yeem muab cov dej khaws cia zoo thiab solubility, tab sis kev hloov pauv siab dhau lossis qis dhau yuav cuam tshuam rau nws txoj haujlwm.
Tus nqi ntxiv: Tus nqi ntxiv ntawm HPMC ncaj qha cuam tshuam rau cov dej tuav ntawm mortar. Feem ntau, qhov sib ntxiv ntawm 0.1% thiab 0.3%. Kev sib ntxiv ntau dhau yuav ua rau tus nqi nce ntxiv thiab tuaj yeem cuam tshuam rau lwm yam khoom ntawm mortar.
Mortar ratio: Qhov piv ntawm lwm yam khoom hauv mortar, xws li cov cement, xuab zeb thiab muab tub lim, kuj yuav cuam tshuam cov dej tuav ntawm HPMC. Tus nqi tsim nyog tuaj yeem ua tau zoo dua lub luag haujlwm ntawm HPMC.
HPMC plays lub luag haujlwm tseem ceeb hauv kev khaws dej hauv tsev mortar los ntawm nws cov qauv tshuaj lom neeg thiab lub cev. Nws cov txheej txheem tseem ceeb suav nrog cov dej adsorbing los tsim cov txheej txheem dej ruaj khov, ua kom cov viscosity viscosity, tsim cov qauv network thiab colloidal barrier, thiab lwm yam. Hauv kev siv tswv yim, HPMC tsis tsuas yog txhim kho kev ua haujlwm thiab kev sib koom ua ke ntawm mortar, tab sis kuj txo qhov kev pheej hmoo ntawm shrinkage thiab tawg. Nyob rau hauv lub neej yav tom ntej, nrog rau kev txhim kho ntawm cov ntaub ntawv science, daim ntawv thov ntawm HPMC nyob rau hauv lub tsev cov ntaub ntawv yuav ntau thiab ntau haiv neeg, thiab txuas ntxiv muab cov kev daws teeb meem zoo rau kev tsim kho kev lag luam.
Post lub sij hawm: Jun-26-2024