Hydroxypropyl methylcellulose (HPMC) yog semi-synthetic, dej-soluble polymer muab los ntawm cellulose.Nws yog dav siv nyob rau hauv ntau yam lag luam, xws li tshuaj, khoom noj khoom haus, kev tsim kho, thiab tshuaj pleev ib ce, vim nws cov yam ntxwv tshwj xeeb xws li thickening, binding, film-forming, thiab stabilizing.Txawm li cas los xij, nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias HPMC tsis muaj qhov tshwj xeeb melting point vim tias nws tsis dhau los ua cov txheej txheem melting tseeb zoo li cov ntaub ntawv crystalline.Hloov chaw, nws dhau los ua cov txheej txheem thermal degradation thaum rhuab.
1. Cov khoom ntawm HPMC:
HPMC yog cov hmoov dawb mus rau dawb tsis muaj ntxhiab tsw, soluble hauv dej thiab ntau cov kuab tshuaj organic.Nws cov khoom sib txawv nyob ntawm seb yam xws li qib kev hloov pauv (DS), qhov hnyav molecular, thiab qhov loj me me.Feem ntau, nws nthuav tawm cov yam ntxwv hauv qab no:
Tsis yog-ionic xwm: HPMC tsis nqa cov nqi hluav taws xob hauv kev daws teeb meem, ua rau nws sib xws nrog ntau yam khoom siv.
Zaj duab xis-tsim: HPMC tuaj yeem tsim cov yeeb yaj kiab meej, hloov tau yooj yim thaum qhuav, uas pom cov ntawv thov hauv cov txheej txheem, cov yeeb yaj kiab, thiab cov ntawv tswj-tso tawm cov tshuaj hauv cov tshuaj.
Thickening agent: Nws imparts viscosity rau cov kev daws teeb meem, ua rau nws muaj txiaj ntsig zoo hauv cov khoom noj khoom haus, tshuaj pleev ib ce, thiab tshuaj.
Hydrophilic: HPMC muaj affinity siab rau dej, uas pab txhawb rau nws solubility thiab zaj duab xis-tsim zog.
2. Synthesis ntawm HPMC:
HPMC yog synthesized los ntawm ntau cov tshuaj tiv thaiv uas muaj cellulose, propylene oxide, thiab methyl chloride.Cov txheej txheem suav nrog etherification ntawm cellulose nrog propylene oxide tom qab los ntawm methylation nrog methyl chloride.Lub degree ntawm kev hloov pauv (DS) ntawm hydroxypropyl thiab methoxy pawg tuaj yeem tswj tau los kho cov khoom ntawm HPMC.
3. Kev siv ntawm HPMC:
Kev lag luam kws tshuaj: HPMC yog dav siv los ua ib qho khoom siv hauv kev tsim tshuaj, suav nrog cov ntsiav tshuaj, tshuaj ntsiav, tshuaj kho qhov muag, thiab cov ntaub ntawv tswj-tso tshuaj.
Kev lag luam khoom noj khoom haus: Nws yog siv los ua cov thickener, stabilizer, thiab emulsifier hauv cov khoom noj xws li kua ntses, kua zaub, ice cream, thiab cov khoom bakery.
Kev tsim kho kev lag luam: HPMC tau ntxiv rau cov khoom siv cement los txhim kho kev ua haujlwm, tuav dej, thiab adhesion.Nws kuj tseem siv tau rau hauv cov nplais nplaum, mortars, thiab renders.
Kev lag luam tshuaj pleev ib ce: HPMC yog siv nyob rau hauv ntau yam tshuaj pleev ib ce xws li cream, tshuaj pleev ib ce, thiab tshuaj zawv plaub hau rau nws cov thickening thiab stabilizing zog.
4. Thermal Behavior ntawm HPMC:
Raws li tau hais ua ntej, HPMC tsis muaj qhov tshwj xeeb melting point vim nws qhov amorphous.Hloov chaw, nws raug thermal degradation thaum rhuab.Cov txheej txheem degradation cuam tshuam nrog kev rhuav tshem cov tshuaj lom neeg hauv cov saw hlau polymer, ua rau tsim cov khoom lag luam tsis zoo.
Qhov kub degradation ntawm HPMC nyob ntawm ntau yam, suav nrog nws qhov hnyav molecular, qib hloov pauv, thiab muaj cov khoom ntxiv.Feem ntau, thermal degradation ntawm HPMC pib nyob ib ncig ntawm 200 ° C thiab nce nrog nce kub.Qhov profile degradation tuaj yeem sib txawv heev nyob ntawm qib tshwj xeeb ntawm HPMC thiab tus nqi cua sov.
Thaum lub sij hawm thermal degradation, HPMC tau dhau los ua ntau yam txheej txheem, suav nrog lub cev qhuav dej, depolymerization, thiab decomposition ntawm pawg ua haujlwm.Cov khoom decomposition tseem ceeb muaj xws li dej, carbon dioxide, carbon monoxide, methanol, thiab ntau yam hydrocarbons.
5. Thermal Analysis Techniques for HPMC:
Cov cwj pwm kub ntawm HPMC tuaj yeem kawm siv ntau yam kev tshuaj ntsuam xyuas, suav nrog:
Thermogravimetric tsom xam (TGA): TGA ntsuas qhov hnyav poob ntawm cov qauv raws li kev ua haujlwm ntawm qhov kub thiab txias, muab cov ntaub ntawv hais txog nws cov thermal stability thiab decomposition kinetics.
Differential scanning calorimetry (DSC): DSC ntsuas cov cua kub ntws mus rau hauv lossis tawm ntawm cov qauv raws li kev ua haujlwm ntawm qhov kub thiab txias, tso cai rau cov yam ntxwv ntawm cov theem hloov thiab cov xwm txheej thermal xws li melting thiab degradation.
Fourier-transform infrared spectroscopy (FTIR): FTIR tuaj yeem siv los saib xyuas cov tshuaj hloov pauv hauv HPMC thaum lub sijhawm thermal degradation los ntawm kev txheeb xyuas cov kev hloov pauv hauv pawg ua haujlwm thiab cov qauv molecular.
6. Xaus:
HPMC yog ntau yam polymer nrog ntau yam kev siv hauv tshuaj, khoom noj, kev tsim kho, thiab tshuaj pleev ib ce.Tsis zoo li cov ntaub ntawv crystalline, HPMC tsis muaj qhov tshwj xeeb melting point tab sis raug thermal degradation thaum rhuab.Qhov kub degradation nyob ntawm ntau yam thiab feem ntau pib ntawm 200 ° C.Kev nkag siab txog tus cwj pwm thermal ntawm HPMC yog qhov tseem ceeb rau nws txoj kev tuav thiab ua tiav hauv kev lag luam sib txawv.
Post lub sij hawm: Mar-09-2024