Kev khaws dej yog ib qho tseem ceeb rau ntau lub lag luam uas siv cov tshuaj hydrophilic xws li cellulose ethers. Hydroxypropylmethylcellulose (HPMC) yog ib qho ntawm cov cellulose ethers uas muaj cov khoom khaws dej siab. HPMC yog ib qho polymer semi-synthetic uas tau los ntawm cellulose thiab feem ntau siv rau hauv ntau yam kev siv hauv kev tsim kho, tshuaj thiab khoom noj.
HPMC siv dav ua cov khoom ua kom tuab, ruaj khov thiab emulsifier hauv ntau yam khoom noj xws li ice cream, kua ntses thiab cov khaub ncaws kom txhim kho lawv cov qauv, kev sib xws thiab lub txee lub neej. HPMC kuj tseem siv rau hauv kev tsim tshuaj hauv kev lag luam tshuaj ua tus neeg sawv cev, tus neeg tawg thiab tus neeg sawv cev txheej zaj duab xis. Nws kuj tseem siv ua tus neeg sawv cev khaws dej hauv cov ntaub ntawv tsim kho, feem ntau yog hauv cov cement thiab mortar.
Kev khaws dej yog ib qho tseem ceeb hauv kev tsim kho vim nws pab tiv thaiv cov cement thiab mortar sib xyaw tshiab kom tsis txhob qhuav. Kev ziab tuaj yeem ua rau shrinkage thiab tawg, ua rau cov qauv tsis muaj zog thiab tsis ruaj khov. HPMC pab tswj cov dej hauv cement thiab mortar los ntawm kev nqus cov dej molecules thiab maj mam tso lawv tawm raws sijhawm, ua rau cov khoom siv hauv tsev kho thiab tawv.
Lub hauv paus ntsiab lus ntawm kev khaws dej ntawm HPMC yog raws li nws cov hydrophilicity. Vim muaj cov hydroxyl pawg (-OH) hauv nws cov qauv molecular, HPMC muaj kev sib raug zoo rau dej. Cov hydroxyl pawg sib cuam tshuam nrog cov dej molecules los tsim cov hydrogen bonds, ua rau muaj lub plhaub hydration nyob ib puag ncig cov saw polymer. Lub plhaub hydrated tso cai rau cov saw polymer kom nthuav dav, ua rau kom muaj ntau ntxiv ntawm HPMC.
Kev o ntawm HPMC yog ib qho txheej txheem dynamic uas nyob ntawm ntau yam xws li qib ntawm kev hloov pauv (DS), qhov loj me ntawm cov khoom me me, kub thiab pH. Qib ntawm kev hloov pauv yog hais txog tus lej ntawm cov pab pawg hydroxyl hloov pauv ib chav anhydroglucose hauv cov saw cellulose. Qhov siab dua tus nqi DS, qhov siab dua hydrophilicity thiab qhov zoo dua qhov kev ua tau zoo ntawm kev khaws dej. Qhov loj me ntawm cov khoom me me ntawm HPMC kuj cuam tshuam rau kev khaws dej, vim tias cov khoom me me muaj thaj chaw loj dua ib chav loj, ua rau nqus dej ntau dua. Qhov kub thiab pH tus nqi cuam tshuam rau qib ntawm kev o thiab kev khaws dej, thiab qhov kub siab dua thiab pH qis dua txhim kho qhov o thiab kev khaws dej ntawm HPMC.
Lub tshuab khaws dej ntawm HPMC muaj ob txoj hauv kev: kev nqus thiab kev tso tawm. Thaum lub sijhawm nqus, HPMC nqus cov dej molecules los ntawm ib puag ncig, tsim lub plhaub hydration nyob ib puag ncig cov saw polymer. Lub plhaub hydration tiv thaiv cov saw polymer los ntawm kev tawg thiab ua rau lawv sib cais, ua rau HPMC o. Cov dej molecules uas nqus tau tsim cov hydrogen bonds nrog cov hydroxyl pawg hauv HPMC, txhim kho kev ua haujlwm khaws dej.
Thaum lub sijhawm desorption, HPMC maj mam tso cov dej molecules, ua rau cov khoom siv hauv tsev kho kom zoo. Qhov tso dej molecules qeeb qeeb ua kom cov cement thiab mortar tseem muaj dej txaus, ua rau muaj cov qauv ruaj khov thiab ruaj khov. Qhov tso dej molecules qeeb qeeb kuj muab dej tsis tu ncua rau cement thiab mortar, txhim kho cov txheej txheem kho thiab ua kom cov khoom kawg muaj zog thiab ruaj khov.
Hauv kev xaus lus, kev khaws dej yog ib qho tseem ceeb rau ntau lub lag luam uas siv cov tshuaj hydrophilic xws li cellulose ethers. HPMC yog ib qho ntawm cov cellulose ethers uas muaj cov khoom khaws dej siab thiab siv dav hauv kev tsim kho, tshuaj thiab khoom noj khoom haus. Cov khoom khaws dej ntawm HPMC yog raws li nws cov hydrophilicity, uas ua rau nws nqus tau cov dej molecules los ntawm ib puag ncig, tsim lub plhaub hydration nyob ib puag ncig cov saw polymer. Lub plhaub hydrated ua rau HPMC o, thiab qhov tso tawm qeeb ntawm cov dej molecules ua kom ntseeg tau tias cov khoom siv hauv tsev tseem hydrated tag nrho, ua rau muaj cov qauv ruaj khov thiab ruaj khov.
Lub sijhawm tshaj tawm: Lub Yim Hli-24-2023