Hydroxypropyl methylcellulose (HPMC)ndi polima osungunuka m'madzi omwe amagwiritsidwa ntchito kwambiri pomanga, mankhwala, chakudya ndi mafakitale opanga mankhwala. Ndiwopanda ionic cellulose ether yomwe imapezedwa ndi kusintha kwa mankhwala a cellulose yachilengedwe, yokhala ndi makulidwe abwino, emulsification, kukhazikika komanso kupanga mafilimu. Komabe, pansi pa kutentha kwakukulu, HPMC idzawonongeka ndi kutentha, zomwe zimakhudza kwambiri kukhazikika kwake ndi ntchito zake zothandiza.
Thermal degradation ndondomeko ya HPMC
Kuwonongeka kwa kutentha kwa HPMC kumaphatikizapo kusintha kwa thupi ndi kusintha kwa mankhwala. Kusintha kwa thupi kumawonetseredwa makamaka ngati kutuluka kwa madzi, kusintha kwa magalasi ndi kuchepetsa kukhuthala, pamene kusintha kwa mankhwala kumaphatikizapo kuwononga mapangidwe a mamolekyu, cleavage yamagulu ogwira ntchito komanso njira yomaliza ya carbonization.
1. Gawo la kutentha kochepa (100-200 ° C): kutuluka kwa madzi ndi kuwonongeka koyambirira
Pansi pa kutentha kwapansi (pafupifupi 100 ° C), HPMC makamaka imatuluka madzi ndi kusintha kwa galasi. Popeza HPMC lili ndi kuchuluka kwa madzi omangika, madzi awa pang'onopang'ono amasanduka nthunzi pa Kutentha, motero zimakhudza ake rheological katundu. Komanso, mamasukidwe akayendedwe a HPMC nawonso kuchepa ndi kuwonjezeka kutentha. Kusintha kwa gawoli makamaka kusintha kwa thupi, pomwe kapangidwe kake kamakhala kosasinthika.
Kutentha kukapitilira kukwera mpaka 150-200 ° C, HPMC imayamba kuchitapo kanthu koyambitsa kuwonongeka kwa mankhwala. Imawonetseredwa makamaka pakuchotsedwa kwa hydroxypropyl ndi methoxy magwiridwe antchito, zomwe zimapangitsa kuchepa kwa kulemera kwa maselo ndi kusintha kwamapangidwe. Panthawiyi, HPMC ikhoza kutulutsa mamolekyu ang'onoang'ono osasunthika, monga methanol ndi propionaldehyde.
2. siteji ya kutentha kwapakati (200-300 ° C): kuwonongeka kwakukulu kwa unyolo ndi mbadwo waung'ono wa molekyulu
Pamene kutentha kumawonjezeka kufika 200-300 ° C, kuchuluka kwa kuwonongeka kwa HPMC kumathamanga kwambiri. Njira zazikulu zowonongera ndizo:
Kuthyoka kwa bondi ya etere: Unyolo waukulu wa HPMC umalumikizidwa ndi mayunitsi a mphete ya glucose, ndipo zomangira za etere zomwe zili mmenemo zimasweka pang'onopang'ono chifukwa cha kutentha kwambiri, zomwe zimapangitsa kuti unyolo wa polima uwonongeke.
Kutaya madzi m'thupi: Dongosolo la mphete ya shuga la HPMC limatha kuchepa madzi m'thupi pa kutentha kwakukulu kuti likhale lapakati losakhazikika, lomwe limawolanso kukhala zinthu zosakhazikika.
Kutulutsidwa kwa ma volatile ang'onoang'ono a mamolekyu: Panthawiyi, HPMC imatulutsa CO, CO₂, H₂O ndi mamolekyu ang'onoang'ono achilengedwe, monga formaldehyde, acetaldehyde ndi acrolein.
Kusintha kumeneku kudzachititsa kuti kulemera kwa maselo a HPMC kugwere kwambiri, kukhuthala kutsika kwambiri, ndipo zinthuzo zidzayamba kusanduka zachikasu komanso kupanga coking.
3. Kutentha kwakukulu (300-500 ° C): carbonization ndi kuphika
Pamene kutentha kumakwera pamwamba pa 300 ° C, HPMC imalowa mu siteji yowonongeka kwambiri. Panthawiyi, kusweka kwina kwa unyolo waukulu ndi kugwedezeka kwa mamolekyu ang'onoang'ono kumayambitsa kuwonongedwa kwa zinthu zonse, ndipo potsiriza kupanga zotsalira za carbonaceous (coke). Zotsatira zotsatirazi zimachitika kwambiri panthawiyi:
Kuwonongeka kwa okosijeni: Pa kutentha kwambiri, HPMC imakumana ndi oxidation reaction kuti ipange CO₂ ndi CO, ndipo nthawi yomweyo imapanga zotsalira za carbon.
Coking reaction: Gawo la polima limasinthidwa kukhala zinthu zosakwanira kuyaka, monga zotsalira za kaboni wakuda kapena coke.
Zogulitsa zopanda mphamvu: Pitirizani kutulutsa ma hydrocarbon monga ethylene, propylene, ndi methane.
Ikatenthedwa mumlengalenga, HPMC imatha kuwotcha, pomwe kutenthetsa popanda mpweya kumapanga zotsalira za carbonized.
Zinthu zomwe zimakhudza kuwonongeka kwa kutentha kwa HPMC
Kuwonongeka kwamafuta kwa HPMC kumakhudzidwa ndi zinthu zambiri, kuphatikiza:
Kapangidwe ka Chemical: Mlingo wa kusintha kwa hydroxypropyl ndi magulu a methoxy mu HPMC kumakhudza kukhazikika kwake kwamafuta. Nthawi zambiri, HPMC yokhala ndi hydroxypropyl yapamwamba imakhala ndi kukhazikika kwamafuta.
Mlengalenga: Mumlengalenga, HPMC imakonda kuwonongeka kwa okosijeni, pomwe ili m'malo a mpweya wa inert (monga nayitrogeni), kutentha kwake kumachepera.
Kutentha kwachangu: Kutentha kofulumira kumayambitsa kuwola kwachangu, pomwe kutentha pang'onopang'ono kungathandize HPMC kuti ikhale ndi mpweya pang'onopang'ono ndikuchepetsa kupanga zinthu zomwe zimawonongeka kwambiri.
Chinyezi: HPMC ili ndi madzi ena omangika. Pa Kutentha ndondomeko, evaporation chinyontho zimakhudza ake galasi kusintha kutentha ndi kuwonongeka ndondomeko.
Kugwiritsa ntchito bwino kwa kuwonongeka kwa kutentha kwa HPMC
Makhalidwe akuwonongeka kwamafuta a HPMC ndi ofunikira kwambiri pakugwiritsa ntchito kwake. Mwachitsanzo:
Makampani omanga: HPMC imagwiritsidwa ntchito mumatope a simenti ndi gypsum, ndipo kukhazikika kwake pakumanga kotentha kwambiri kuyenera kuganiziridwa kuti zisawonongeke zomwe zingakhudze magwiridwe antchito.
Makampani opanga mankhwala: HPMC ndi mankhwala otulutsidwa ndi mankhwala, ndipo kuwonongeka kuyenera kupewedwa panthawi yotentha kwambiri kuti mankhwalawa atsimikizidwe.
Makampani azakudya: HPMC ndi chowonjezera chazakudya, ndipo mawonekedwe ake owonongeka amawona momwe angagwiritsire ntchito pakuphika ndi kukonza kutentha kwambiri.
The matenthedwe kuwonongeka ndondomekoMtengo wa HPMCakhoza kugawidwa mu evaporation madzi ndi kuwonongeka koyambirira mu siteji otsika kutentha, waukulu unyolo cleavage ndi yaing'ono molekyulu volatilization mu sing'anga-kutentha siteji, ndi carbonization ndi coking mu siteji mkulu-kutentha. Kukhazikika kwake kwamafuta kumakhudzidwa ndi zinthu monga kapangidwe ka mankhwala, mlengalenga wozungulira, kutentha kwa kutentha ndi chinyezi. Kumvetsetsa njira yochepetsera kutentha kwa HPMC ndikofunika kwambiri kukhathamiritsa ntchito yake ndikuwongolera kukhazikika kwazinthu.
Nthawi yotumiza: Mar-28-2025