I-Hydroxypropyl methylcellulose (HPMC)iyinhlanganisela ye-polymer encibilika emanzini esetshenziswa kabanzi ekwakhiweni, kwezokwelapha, ezimbonini zokudla namakhemikhali. I-ether engeyona i-ionic cellulose etholwe ngokuguqulwa kwamakhemikhali we-cellulose yemvelo, enokuqina okuhle, i-emulsification, ukuqiniswa kanye nezakhiwo zefilimu. Kodwa-ke, ngaphansi kwezimo zokushisa eziphakeme, i-HPMC izobhekana nokuwohloka kokushisa, okunomthelela obalulekile ekuzinzeni nasekusebenzeni kwayo ekusebenzeni okungokoqobo.
Inqubo yokuwohloka kokushisa kwe-HPMC
Ukuwohloka kokushisa kwe-HPMC kufaka phakathi izinguquko zomzimba kanye nezinguquko zamakhemikhali. Izinguquko zomzimba zibonakaliswa ngokuyinhloko njengokuhwamuka kwamanzi, ukuguqulwa kwengilazi kanye nokunciphisa i-viscosity, kuyilapho ukuguqulwa kwamakhemikhali kuhilela ukubhujiswa kwesakhiwo samangqamuzana, i-cleavage yeqembu elisebenzayo kanye nenqubo yokugcina ye-carbonization.
1. Isigaba sokushisa esiphansi (100-200 ° C): ukuhwamuka kwamanzi nokubola kokuqala
Ngaphansi kwezimo zokushisa eziphansi (cishe u-100°C), i-HPMC ithola ukuhwamuka kwamanzi kanye nokushintsha kwengilazi. Njengoba i-HPMC iqukethe inani elithile lamanzi aboshwe, la manzi azohwamuka kancane kancane ngesikhathi sokushisa, ngaleyo ndlela athinte izakhiwo zawo ze-rheological. Ngaphezu kwalokho, i-viscosity ye-HPMC nayo izokwehla ngokunyuka kwezinga lokushisa. Izinguquko kulesi sigaba ngokuyinhloko ziyizinguquko ezimpahleni ezibonakalayo, kuyilapho isakhiwo samakhemikhali sihlala singashintshile.
Lapho izinga lokushisa liqhubeka nokukhuphuka lifinyelele ku-150-200°C, i-HPMC iqala ukubhekana nokusabela kokuqala kokuwohloka kwamakhemikhali. Ibonakala ngokuyinhloko ekukhishweni kwamaqembu asebenzayo e-hydroxypropyl kanye ne-methoxy, okuholela ekwehleni kwesisindo samangqamuzana kanye nezinguquko zesakhiwo. Kulesi sigaba, i-HPMC ingase ikhiqize inani elincane lama-molecule aguquguqukayo, njenge-methanol ne-propionaldehyde.
2. Isiteji sokushisa esimaphakathi (200-300°C): ukuwohloka kweketango eliyinhloko kanye nokukhiqizwa kwe-molecule encane
Lapho izinga lokushisa liphinde lenyuka libe ngu-200-300°C, izinga lokubola le-HPMC liyashesha kakhulu. Izindlela eziyinhloko zokwehlisa isithunzi zihlanganisa:
Ukuphuka kwebhondi ye-Ether: Iketango eliyinhloko le-HPMC lixhunywe amayunithi endandatho ye-glucose, futhi amabhondi e-ether kuwo kancane kancane aphuka ngaphansi kwezinga lokushisa eliphezulu, okubangela ukuba iketango le-polymer libole.
Ukusabela kokuphelelwa amanzi emzimbeni: Isakhiwo seringi kashukela se-HPMC singase sibhekane nokusabela kokuphelelwa amanzi emzimbeni ezingeni lokushisa eliphezulu ukuze kwakhe indawo emaphakathi engazinzile, ephinde iboliswe ibe yimikhiqizo eguquguqukayo.
Ukukhishwa kwezivunguvungu ze-molecule encane: Phakathi nalesi sigaba, i-HPMC ikhipha i-CO, i-CO₂, i-H₂O kanye ne-organic molecule encane, njenge-formaldehyde, i-acetaldehyde ne-acrolein.
Lezi zinguquko zizobangela ukuthi isisindo samangqamuzana e-HPMC sehle kakhulu, i-viscosity yehle kakhulu, futhi impahla izoqala ukuphenduka ibe phuzi futhi ikhiqize i-coking.
3. Isiteji sokushisa esiphezulu (300-500 ° C): i-carbonization ne-coking
Lapho izinga lokushisa likhuphuka ngaphezu kuka-300°C, i-HPMC ingena esigabeni sokucekela phansi ngobudlova. Ngalesi sikhathi, ukuphuka okuqhubekayo kweketango eliyinhloko kanye nokuguquguquka kwezakhi ezincane ze-molecule kuholela ekubhujisweni okuphelele kwesakhiwo sezinto ezibonakalayo, futhi ekugcineni kwakha izinsalela ze-carbonaceous (coke). Ukusabela okulandelayo kwenzeka kakhulu kulesi sigaba:
Ukuwohloka kwe-oxidative: Emazingeni okushisa aphezulu, i-HPMC ithola ukusabela kwe-oxidation ukuze ikhiqize i-CO₂ ne-CO, futhi ngesikhathi esifanayo yenza izinsalela ze-carbonaceous.
Ukusabela kwe-coking: Ingxenye yesakhiwo se-polymer iguqulwa ibe imikhiqizo evuthayo engaphelele, efana ne-carbon black noma izinsalela ze-coke.
Imikhiqizo eguquguqukayo: Qhubeka nokukhipha ama-hydrocarbon afana ne-ethylene, i-propylene, ne-methane.
Uma ishiswa emoyeni, i-HPMC ingase iqhubeke ivutha, kuyilapho ukufudumeza lapho ungekho umoya-mpilo ikakhulukazi kwakha izinsalela zekhabhoni.
Izinto ezithinta ukuwohloka kokushisa kwe-HPMC
Ukuwohloka okushisayo kwe-HPMC kuthintwa izinto eziningi, okuhlanganisa:
Isakhiwo samakhemikhali: Izinga lokushintshanisa i-hydroxypropyl namaqembu e-methoxy ku-HPMC lithinta ukuqina kwayo kokushisayo. Ngokuvamile, i-HPMC enokuqukethwe okuphezulu kwe-hydroxypropyl inokusimama okungcono kokushisa.
Umkhathi we-Ambient: Emoyeni, i-HPMC ijwayele ukuwohloka kwe-oxidative, kuyilapho isendaweni yegesi engasebenzi (njenge-nitrogen), izinga layo lokuwohloka kokushisa lihamba kancane.
Izinga lokushisisa: Ukushisisa okusheshayo kuzoholela ekuboleni okusheshayo, kuyilapho ukushisisa kancane kungasiza i-HPMC ukuthi ikhiphe ikhabhoni kancane kancane futhi yehlise ukukhiqizwa kwemikhiqizo eshintshashintshayo.
Okuqukethwe komswakama: I-HPMC iqukethe inani elithile lamanzi ahlanganisiwe. Phakathi nenqubo yokushisa, ukuhwamuka komswakama kuzothinta izinga lokushisa lokushintsha kwengilazi kanye nenqubo yokuwohloka.
Umthelela osebenzayo wokuwohloka kokushisa kwe-HPMC
Izici zokuwohloka kokushisa kwe-HPMC zibaluleke kakhulu emkhakheni wayo wohlelo. Ngokwesibonelo:
Imboni yezokwakha: I-HPMC isetshenziswa odakeni lukasimende kanye nemikhiqizo yegypsum, futhi ukuzinza kwayo ngesikhathi sokwakhiwa kwezinga lokushisa eliphezulu kufanele kubhekwe ukugwema ukuwohloka okuthinta ukusebenza kwebhondi.
Imboni eyenza imithi: I-HPMC iyi-ejenti ekhishwayo elawulwa yisidakamizwa, futhi ukubola kufanele kugwenywe ngesikhathi sokukhiqizwa okunezinga lokushisa eliphezulu ukuze kuqinisekiswe ukuzinza komuthi.
Imboni yokudla: I-HPMC iyisengezo sokudla, futhi izici zayo zokuwohloka kokushisa zinquma ukusebenza kwayo ekubhakeni nasekusetshenzisweni okunezinga lokushisa eliphezulu.
Inqubo yokuwohloka kokushisa kweI-HPMCingahlukaniswa ibe ukuhwamuka kwamanzi kanye nokuwohloka kokuqala esigabeni sezinga lokushisa eliphansi, i-chain cleavage enkulu kanye ne-molecule encane ye-volatilization esigabeni sezinga lokushisa eliphakathi, kanye ne-carbonization kanye ne-coking esigabeni sokushisa okuphezulu. Ukuzinza kwayo okushisayo kuthinteka yizinto ezifana nesakhiwo samakhemikhali, umoya ozungezile, izinga lokushisa kanye nomswakama. Ukuqonda indlela yokuwohloka kokushisa kwe-HPMC kunenani elikhulu ukuze kusetshenziswe ngokugcwele futhi kuthuthukiswe ukuqina kwezinto.
Isikhathi sokuthumela: Mar-28-2025