Tsom ntsoov rau Cellulose ethers

Dab tsi yog yam tseem ceeb uas cuam tshuam rau cov dej tuav ntawm HPMC cov khoom?

Hydroxypropyl methylcellulose (HPMC, Hydroxypropyl Methylcellulose) yog ib qho tseem ceeb ntawm cellulose ether, dav siv hauv kev tsim kho, tshuaj, zaub mov thiab lwm yam, thiab tshwj xeeb tshaj yog nyob rau hauv cov khoom siv hauv tsev. Kev tuav dej ntawm HPMC yog ib qho ntawm nws cov khoom tseem ceeb thiab ua lub luag haujlwm tseem ceeb hauv kev ua tau zoo ntawm ntau yam kev thov. Cov yam ntxwv uas cuam tshuam rau cov dej tuav ntawm HPMC suav nrog cov qauv molecular, qib ntawm kev hloov pauv, qhov hnyav molecular, solubility, ambient kub, additives, thiab lwm yam.

1. Molecular qauv
HPMC yog cellulose derivative uas nws cov qauv molecular muaj feem cuam tshuam rau cov dej tuav. Cov qauv molecular ntawm HPMC muaj hydrophilic hydroxyl (-OH), lipophilic methyl (-CH₃) thiab hydroxypropyl (-CH₂CHOHCH₃). Qhov kev faib ua feem thiab kev faib tawm ntawm cov pab pawg hydrophilic thiab lipophilic muaj qhov cuam tshuam ncaj qha rau kev tuav dej ntawm HPMC.

Lub luag haujlwm ntawm pawg hydroxyl: Cov pab pawg Hydroxyl yog pawg hydrophilic uas tuaj yeem tsim cov hydrogen bonds nrog cov dej molecules, yog li pab txhim kho cov dej tuav ntawm HPMC.
Lub luag haujlwm ntawm methyl thiab hydroxypropyl pawg: Cov pab pawg no yog hydrophobic thiab tuaj yeem cuam tshuam rau solubility thiab gelation kub ntawm HPMC hauv dej, yog li cuam tshuam rau cov dej tuav dej.

2. Kev hloov pauv
Qib ntawm kev hloov pauv (DS) yog hais txog qhov nruab nrab ntawm cov neeg hloov pauv hydroxyl pawg hauv cellulose molecules. Rau HPMC, qib ntawm kev hloov ntawm methoxy (-OCH₃) thiab hydroxypropoxy (-OCH₂CHOHCH₃) feem ntau yog kev txhawj xeeb, uas yog, qib ntawm kev hloov ntawm methoxy (MS) thiab qib ntawm kev hloov ntawm hydroxypropoxy (HP):

Kev hloov pauv siab: Qhov siab dua qhov hloov pauv, ntau pawg hydrophilic HPMC muaj, thiab theoretically cov dej tuav yuav raug txhim kho. Txawm li cas los xij, kev hloov pauv ntau dhau tuaj yeem ua rau muaj kev solubility ntau dhau, thiab cov nyhuv tuav dej yuav raug txo.
Qib qis ntawm kev hloov pauv: HPMC nrog qib qis ntawm kev hloov pauv muaj cov dej tsis zoo hauv cov dej, tab sis cov qauv tsim hauv lub network yuav ruaj khov dua, yog li tswj xyuas cov dej zoo dua.
Kev kho cov qib ntawm kev hloov pauv hauv qee qhov ntau tuaj yeem txhim kho cov dej tuav ntawm HPMC. Kev hloov pauv ntau yam feem ntau yog 19-30% rau methoxy thiab 4-12% rau hydroxypropoxy.

3. Molecular hnyav
Qhov hnyav molecular ntawm HPMC muaj qhov cuam tshuam loj rau nws cov dej tuav:

Qhov hnyav molecular: HPMC nrog qhov hnyav molecular muaj cov saw hlau ntev dua thiab tsim cov qauv sib txuas, uas tuaj yeem ua kom haum thiab khaws cov dej ntau dua, yog li txhim kho dej tuav.
Tsawg molecular yuag: HPMC uas tsis tshua muaj molecular hnyav muaj luv luv molecules thiab kuj tsis muaj zog tuav lub peev xwm, tab sis muaj zoo solubility thiab yog haum rau daim ntaub ntawv uas yuav tsum tau sai dua dissolution.
Feem ntau, qhov hnyav molecular ntau ntawm HPMC siv hauv cov khoom siv hauv tsev yog li ntawm 80,000 txog 200,000.

4. Solubility
Lub solubility ntawm HPMC ncaj qha cuam tshuam nws cov dej tuav. Zoo solubility pab HPMC kom tag nrho dispersed nyob rau hauv lub matrix, yog li tsim ib tug uniform dej-tswj qauv. Solubility yog cuam tshuam los ntawm:

Dissolution kub: HPMC dissolves maj mam nyob rau hauv dej txias, tab sis dissolves sai dua nyob rau hauv dej sov. Txawm li cas los xij, qhov kub thiab txias dhau yuav ua rau HPMC yaj ntau dhau, cuam tshuam rau nws cov qauv dej khaws cia.
pH tus nqi: HPMC yog rhiab heev rau pH tus nqi thiab muaj zoo solubility nyob rau hauv nruab nrab los yog tsis muaj zog acidic ib puag ncig. Nws yuav degrade los yog txo solubility nyob rau hauv huab pH qhov tseem ceeb.

5. Ambient kub
Qhov kub thiab txias muaj qhov cuam tshuam loj rau kev tuav dej ntawm HPMC:

Tsis tshua muaj kub: Ntawm qhov kub thiab txias, qhov solubility ntawm HPMC txo, tab sis cov viscosity siab dua, uas tuaj yeem tsim cov qauv dej ruaj khov dua.
Qhov kub thiab txias: Qhov kub siab ua kom nrawm nrawm ntawm HPMC, tab sis tej zaum yuav ua rau muaj kev puas tsuaj rau cov dej tuav cov qauv thiab cuam tshuam rau nws cov dej tuav. Feem ntau, kev tuav dej zoo tuaj yeem khaws cia hauv qab 40 ℃.

6. Cov tshuaj ntxiv
HPMC feem ntau siv ua ke nrog lwm cov khoom siv ntxiv hauv kev siv tswv yim. Cov additives no tuaj yeem cuam tshuam cov dej tuav ntawm HPMC:

Plasticizers: xws li glycerol thiab ethylene glycol, uas tuaj yeem txhim kho qhov yooj yim thiab dej tuav ntawm HPMC.
Fillers: xws li gypsum thiab quartz hmoov, yuav cuam tshuam cov dej tuav ntawm HPMC thiab hloov nws cov dispersion thiab dissolution yam ntxwv los ntawm kev cuam tshuam nrog HPMC.

7. Cov xwm txheej thov
Cov dej tuav dej ntawm HPMC kuj tseem yuav cuam tshuam raws li kev thov sib txawv:

Kev tsim kho: xws li lub sijhawm tsim kho, ib puag ncig cov av noo, thiab lwm yam yuav cuam tshuam rau cov dej tuav ntawm HPMC.
Tus nqi siv: Tus nqi ntawm HPMC ncaj qha cuam tshuam rau cov dej tuav. Feem ntau, HPMC nrog ntau npaum li cas qhia tau zoo dua cov dej tuav hauv cov cement mortar thiab lwm yam ntaub ntawv.

Muaj ntau yam uas cuam tshuam rau cov dej tuav ntawm HPMC, suav nrog nws cov qauv molecular, qib kev hloov pauv, qhov hnyav molecular, solubility, ambient kub, additives, thiab cov kev siv tiag tiag. Thaum lub sijhawm ua ntawv thov, los ntawm kev xaiv thiab hloov kho cov yam ntxwv no, cov dej khaws cia ntawm HPMC tuaj yeem txhim kho kom tau raws li qhov xav tau ntawm ntau qhov chaw.


Post lub sij hawm: Jun-24-2024
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