Hydroxypropyl methylcellulose (HPMC)inzvimbo inonyungudika nemvura yepolymer inoshandiswa zvakanyanya mukuvaka, mishonga, chikafu uye maindasitiri emakemikari. Iyo isiri-ionic cellulose ether inowanikwa nekugadziriswa kwemakemikari echisikigo cellulose, ine yakanaka thickening, emulsification, kudzikamisa uye firimu-kugadzira zvinhu. Nekudaro, pasi pemamiriro ekushisa akanyanya, HPMC ichaita kuderedzwa kwekupisa, izvo zvine chekuita kwakakosha pakugadzikana kwayo uye kuita kwayo mukushandisa zvinoshanda.
Thermal degradation process yeHPMC
Kushatisa kwekupisa kweHPMC kunonyanya kusanganisira shanduko yemuviri uye shanduko yemakemikari. Kuchinja kwemuviri kunonyanya kuratidzwa sekubuda kwemvura, kushanduka kwegirazi uye kuderedzwa kwe viscosity, nepo shanduko yemakemikari inosanganisira kuparadzwa kweiyo molecular chimiro, inoshanda boka cleavage uye yekupedzisira carbonization process.
1. Kupisa kwepasi (100-200 ° C): kubuda kwemvura uye kuora kwekutanga
Pasi petembiricha yakaderera (yakatenderedza 100 ° C), HPMC inonyanya kupinda mumvura evaporation uye girazi shanduko. Sezvo HPMC ine imwe chiyero chemvura yakasungwa, mvura iyi inoputika zvishoma nezvishoma panguva yekupisa, zvichikanganisa rheological properties. Mukuwedzera, iyo viscosity yeHPMC inodererawo nekuwedzera kwekushisa. Shanduko dziri pachinhanho ichi dzinonyanya kuchinja mune zvemuviri zvimiro, nepo chimiro chemakemikari chinoramba chisina kuchinjika.
Kana tembiricha ikaramba ichikwira kusvika 150-200°C, HPMC inotanga kusangana nemaitiro ekutanga ekuderedza kemikari. Inonyanya kuratidzwa mukubviswa kwehydroxypropyl uye methoxy functional groups, zvichikonzera kuderera kwehuremu hwema molecular uye kuchinja kwemaitiro. Panguva ino, HPMC inogona kuburitsa diki diki diki mamorekuru, senge methanol uye propionaldehyde.
2. Yepakati tembiricha nhanho (200-300 ° C): huru cheni kushatisa uye diki molecule chizvarwa.
Kana tembiricha ichiwedzerwa kusvika 200-300 ° C, chiyero chekuora cheHPMC chinowedzera zvakanyanya. Iwo makuru ekuderedza maitiro anosanganisira:
Ether bond breakage: The main chain of HPMC yakabatanidzwa neglucose ring units, uye ether zvisungo zviri mairi zvishoma nezvishoma zvinoputika pasi pekushisa kwepamusoro, zvichiita kuti polymer chain iparare.
Dehydration reaction: Chimiro cheshuga cheHPMC chinogona kuita dehydration reaction patembiricha yakakwira kuti iite isina kugadzikana yepakati, iyo inozoora zvakare kuita zvigadzirwa zvinoshanduka.
Kuburitswa kwemamorekuru madiki anoputika: Panguva ino, HPMC inoburitsa CO, CO₂, H₂O uye diki molecule organic zvinhu, senge formaldehyde, acetaldehyde uye acrolein.
Shanduko idzi dzinoita kuti huremu hweHPMC hudonhe zvakanyanya, viscosity idonhe zvakanyanya, uye zvinhu zvinotanga kushanduka yero uye kuburitsa coking.
3. Kupisa kwepamusoro (300-500 ° C): carbonization uye coking
Kana tembiricha ichikwira pamusoro 300 ° C, HPMC inopinda nechisimba degradation stage. Panguva ino, kumwe kuparara kweketani huru uye kuvhuvhuta kwemakemikari maduku maduku kunotungamirira kukuparadzwa kwakakwana kwechimiro chechimiro, uye pakupedzisira kuumba masara e carbonaceous (coke). Izvi zvinotevera zvinonyanya kuitika panguva ino:
Oxidative degradation: Pakupisa kwepamusoro, HPMC inopinda oxidation reaction kuti igadzire CO₂ neCO, uye panguva imwe chete inogadzira zvisaririra zvekabhoni.
Coking reaction: Chikamu chepolymer chimiro chinoshandurwa kuita zvisina kukwana zvigadzirwa zvekupisa, senge kabhoni dema kana coke masara.
Zvigadzirwa zvinoshanduka: Ramba uchiburitsa mahydrocarbon akadai seethylene, propylene, uye methane.
Kana yapisa mumhepo, HPMC inogona kuwedzera kupisa, uku kudziyisa pasina okisijeni kunonyanya kuumba masara ecarbonized.
Zvinhu zvinokanganisa kupisa kwekupisa kweHPMC
Kushatisa kwekupisa kweHPMC kunokanganiswa nezvakawanda zvinhu, zvinosanganisira:
Chimiro chemakemikari: Iyo dhigirii yekutsiviwa kwehydroxypropyl uye methoxy mapoka muHPMC inokanganisa kugadzikana kwayo kwekupisa. Kazhinji kutaura, HPMC ine yepamusoro hydroxypropyl yemukati ine zvirinani kugadzikana kwekupisa.
Ambient atmosphere: Mumhepo, HPMC inowanzoita oxidative degradation, ichiri munzvimbo inert gasi (senge nitrogen), mwero wekupisa kwayo unononoka.
Mwero wekupisa: Kukurumidza kupisa kunotungamira mukuora nekukurumidza, nepo kudziyisa zvishoma nezvishoma kunogona kubatsira HPMC kuita zvishoma nezvishoma carbonize uye kuderedza kugadzirwa kwegasi rinoputika zvigadzirwa.
Hunyoro hwemukati: HPMC ine imwe huwandu hwemvura yakasungwa. Munguva yekudziya maitiro, iyo evaporation yehunyoro inozokanganisa yayo yegirazi tembiricha tembiricha uye degradation maitiro.
Kushanda kwekushandisa kukanganisa kwekupisa kwekupisa kweHPMC
Iwo hunhu hwekupisa hwekupisa hweHPMC hwakakosha zvikuru mundima yayo yekushandisa. Semuyenzaniso:
Indasitiri yekuvaka: HPMC inoshandiswa musimende dhaka uye zvigadzirwa zvegypsum, uye kugadzikana kwayo panguva yekuvaka-yepamusoro-tembiricha kunofanirwa kutariswa kudzivirira kusvibiswa kunokanganisa kushanda kwechisungo.
Indasitiri yemishonga: HPMC idhiza rinodzorwa kuburitsa mumiriri, uye kuora kunofanirwa kudzivirirwa panguva yekugadzirwa kwepamusoro-tembiricha kuve nechokwadi chekugadzikana kwemushonga.
Indasitiri yechikafu: HPMC ndeyekuwedzera kwechikafu, uye hunhu hwayo hwekudzikisira kupisa hunoratidza kushanda kwayo mukupisa kwepamusoro-tembiricha yekubheka uye kugadzirisa.
The thermal degradation process yeHPMCinogona kukamurwa kuita evaporation yemvura uye kuparara kwekutanga mune yakaderera-tembiricha nhanho, huru cheni cleavage uye diki molecule volatilization mune yepakati-tembiricha nhanho, uye carbonization uye coking mune yakakwirira-tembiricha nhanho. Kugadzikana kwayo kwekupisa kunokanganiswa nezvinhu zvakaita sechimiro chemakemikari, ambient atmosphere, kudziyisa mwero uye hunyoro. Kunzwisisa nzira yekupisa yekupisa yeHPMC yakakosha zvikuru kukwirisa mashandisirwo ayo uye kugadzirisa kugadzikana kwezvinhu.
Nguva yekutumira: Mar-28-2025