Hydroxypropyl methylcellulose (HPMC) yog cov khoom siv dej-soluble polymer dav siv hauv tshuaj, khoom noj, kev tsim kho thiab lwm yam. Nws muaj qhov zoo thermal stability, tab sis nws tseem yuav degrade nyob rau hauv siab kub. Qhov kub degradation ntawm HPMC feem ntau cuam tshuam los ntawm nws cov qauv molecular, ib puag ncig tej yam kev mob (xws li av noo, pH nqi) thiab lub sij hawm cua sov.
Degradation kub ntawm HPMC
Lub thermal degradation ntawm HPMC feem ntau pib tshwm saum 200℃, thiab pom tseeb decomposition yuav tshwm sim ntawm 250℃-300℃. Tshwj xeeb:
Hauv qab 100℃: HPMC feem ntau qhia cov dej evaporation thiab kev hloov ntawm lub cev, thiab tsis muaj degradation tshwm sim.
100℃-200℃: HPMC tuaj yeem ua rau oxidation ib nrab vim qhov kub hauv zos nce, tab sis nws ruaj khov tag nrho.
200℃-250℃: HPMC maj mam qhia cov thermal degradation, uas yog feem ntau tshwm sim raws li cov qauv tawg thiab tso tawm me me molecular volatiles.
250℃-300℃: HPMC ua rau pom tseeb decomposition, xim yuav tsaus, me me molecules xws li dej, methanol, acetic acid raug tso tawm, thiab carbonization tshwm sim.
Tshaj 300℃: HPMC degrades sai sai thiab carbonizes, thiab qee yam inorganic tshuaj nyob rau hauv kawg.
Cov xwm txheej cuam tshuam rau HPMC degradation
Molecular hnyav thiab degree ntawm kev hloov
Thaum qhov hnyav molecular ntawm HPMC loj, nws qhov kub tsis kam yog feem ntau siab.
Qib ntawm kev hloov ntawm methoxy thiab hydroxypropoxy pawg yuav cuam tshuam rau nws cov thermal stability. HPMC nrog qib siab dua ntawm kev hloov pauv tau yooj yim dua degraded ntawm qhov kub thiab txias.
Environmental yam
Humidity: HPMC muaj zog hygroscopicity, thiab noo noo yuav ua kom nws degradation ntawm qhov kub thiab txias.
Tus nqi pH: HPMC yog qhov cuam tshuam rau hydrolysis thiab degradation nyob rau hauv cov kua qaub lossis alkali muaj zog.
Lub sijhawm cua sov
Kub rau 250℃rau ib lub sij hawm luv luv tej zaum yuav tsis tag decompose, thaum tswj kub siab rau ib lub sij hawm ntev yuav ceev cov txheej txheem degradation.
Cov khoom degradation ntawm HPMC
HPMC feem ntau yog muab los ntawm cellulose, thiab nws cov khoom degradation zoo ib yam li cellulose. Thaum lub sijhawm cua sov, cov hauv qab no tuaj yeem raug tso tawm:
Dej vapor (los ntawm pawg hydroxyl)
Methanol, ethanol (los ntawm methoxy thiab hydroxypropoxy pawg)
Acetic acid (los ntawm cov khoom decomposition)
Cov pa roj carbon monoxide (CO, CO₂, tsim los ntawm combustion ntawm organic teeb meem)
Ib qho me me ntawm coke residue
Daim ntawv thov kub tsis kam ntawm HPMC
Txawm hais tias HPMC yuav maj mam txo qis dua 200℃, feem ntau nws tsis raug rau qhov kub siab no hauv kev siv tiag tiag. Piv txwv li:
Kev lag luam kws tshuaj: HPMC feem ntau yog siv rau cov ntsiav tshuaj txheej thiab cov neeg ua haujlwm tso tawm, feem ntau ua haujlwm ntawm 60℃-80℃, uas yog qis dua nws qhov kub thiab txias degradation.
Kev lag luam khoom noj khoom haus: HPMC tuaj yeem siv los ua cov thickener lossis emulsifier, thiab cov pa siv kub feem ntau tsis ntau tshaj 100℃.
Kev tsim kho kev lag luam: HPMC yog siv los ua cov cement thiab mortar thickener, thiab kev tsim kho kub feem ntau tsis tshaj 80℃, thiab tsis muaj degradation yuav tshwm sim.
HPMC pib thermally degrade saum 200℃, decomposes tseem ceeb ntawm 250℃-300℃, thiab carbonizes sai dua 300℃. Nyob rau hauv kev siv tswv yim, lub sij hawm ntev raug rau qhov kub thiab txias ib puag ncig yuav tsum tau zam kom nws ruaj khov.
Post lub sij hawm: Apr-03-2025