I-Hydroxypropyl methylcellulose (HPMC)Ikhompiyutha esetshenziswa ngamanzi esetshenziswa kabanzi ekwakheni, umuthi, ukudla kanye nezimboni zamakhemikhali. Kuyi-ether ye-celtulose engeyona eye-ionic etholwe ukuguqulwa kwamakhemikhali kwemvelo yeselula, ngokuqina okuhle, ukukhulisa, ukuzinza kwezinzayo kanye nezakhiwo ezenziwe ngefilimu. Kodwa-ke, ngaphansi kwezimo zokushisa eziphakeme, i-HPMC izobhekana nokuwohloka okushisayo, okunomthelela obalulekile ekuqineni nasekusebenzeni kwayo ezinhlelweni ezisebenzayo.
Inqubo yokuwohloka kwe-thermal ye-HPMC
Ukuwohloka okushisayo kwe-HPMC ikakhulukazi kufaka izinguquko zomzimba kanye nezinguquko zamakhemikhali. Izinguquko ezenziwa ngokomzimba zibonakaliswa ikakhulukazi njengokuhwamuka kwamanzi, ukuguqulwa kwengilazi kanye nokuncishiswa kwe-viscosity, kuyilapho ushintsho lwamakhemikhali lubandakanya ukubhujiswa kwesakhiwo samangqamuzana, inqubo yeqembu elisebenzayo kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization kanye nenqubo yokugcina ye-carbonization nenqubo yokugcina.
1. Isigaba sokushisa esiphansi (100-200 ° C): Ukuhanjiswa kwamanzi kanye nokubola kokuqala
Ngaphansi kwezimo zokushisa eziphansi (cishe ngo-100 ° C), i-HPMC ikakhulukazi ithola ukuhwamuka kwamanzi kanye nenguquko yengilazi. Njengoba i-HPMC iqukethe inani elithile lamanzi aboshwe, la manzi azoshintsha kancane ngesikhathi sokushisa, ngaleyo ndlela athinta izakhiwo zawo ze-rherological. Ngaphezu kwalokho, i-viscosity ye-HPMC izokwehla futhi ngokwanda kokushisa. Izinguquko ezikulesi sigaba ziyizinguquko ikakhulukazi ezintweni ezibonakalayo, ngenkathi ukwakheka kwamakhemikhali kuhlala kungashintshiwe.
Lapho amazinga okushisa eqhubeka ekhuphuka ku-150-200 ° C, i-HPMC iqala ukubhekana nokungezwani kwamakhemikhali kwamakhemikhali. Kubonakaliswa ikakhulukazi ekususweni kwamaqembu we-hydroxypropyl kanye ne-methoxy funcy, okuholela ekunciphiseni isisindo molecular izinguquko. Kulesi sigaba, i-HPMC ingakhiqiza inani elincane lama-molecule amancane aguqukayo, njenge-methanol kanye ne-proptionaldehyde.
2. Isiteji sokushisa esiphakathi (200-300 ° C): Ukuwohloka okukhulu kwe-chain kanye nesizukulwane esincane se-molecule
Lapho izinga lokushisa lenyuka futhi liye ku-200-300 ° C, isilinganiso sokukhomba kwe-HPMC sisheshiswa kakhulu. Izindlela eziphambili zokucekelwa phansi zifaka:
Ukuqhekeka kwe-Ether Bond: Iketanga eliphambili le-HPMC lixhumeke ngamayunithi we-glucose ring, kanye nama-ether lyring kuwo kancane kancane aphule ngaphansi kwezinga lokushisa eliphakeme, okwenza i-polymer chain ibole.
Ukusabela kwe-DeHydration: Ukwakheka kwendandatho kashukela kwe-HPMC kungabhekana nokusabela kokuwohloka kokushisa okuphezulu ukuze kwakhiwe i-Intermediate engazinzile, ebolile eminye imikhiqizo eguquguqukayo.
Ukukhishwa kwama-volatiles amancane we-molecule: Ngesikhathi lesi sigaba, i-HPMC ikhipha i-CO, Co₂, H₂O kanye ne-molecule ephathekayo ye-organic, njenge-formaldehyde, njenge-formaldehyde, i-acetaldehyde ne-agralein.
Lezi zinguquko zizodala isisindo se-molecular ye-HPMC ukuthi sehlise kakhulu, i-viscosity yehla kakhulu, futhi okuqukethwe kuzoqala ukuphenduka okuphuzi futhi kukhiqize ukukhwehlela.
I-3. Isigaba esiphakeme sokushisa (300-500 ° C): I-Carbonization kanye ne-Coking
Lapho amazinga okushisa enyuka ngenhla kwama-300 ° C, i-HPMC ingena esigabeni sokonakalisa esinobudlova. Ngalesi sikhathi, ukuqhekeka okwengeziwe kweketanga eliyinhloko nokuthambekela kokuthambekela kwamakhompiyutha amancane amancane kuholela ekubhujisweni okuphelele kwesakhiwo esibonakalayo, bese ekugcineni kwakha izinsalela ze-carbonaceous (coke). Ukuphendula okulandelayo kwenzeke ikakhulukazi kulesi sigaba:
Ukuwohloka kwe-oxidative: Ekushiseni okuphezulu, i-HPMC ifuna ukusabela oxidation ukukhiqiza i-co₂ ne-co, futhi ngasikhathi sinye izinsalela ze-Carbonaceous.
Ukusabela kwe-Cking: Ingxenye yesakhiwo se-polymer iguqulwa ibe yimikhiqizo yokuhlanganisa engaphelele, njengezinsalela zekhabhoni ezimnyama noma ze-coke.
Imikhiqizo eguquguqukayo: Qhubeka nokukhulula ama-hydrocarbons anjenge-ethylene, i-propylene, kanye ne-methane.
Lapho kufudunyezwa emoyeni, i-HPMC ingahle ishise, ngenkathi ukufudumeza ukungabikho komoya-mpilo kuba yindlela eyakha izinsalela.
Izici ezithinta ukonakala okushisayo kwe-HPMC
Ukuwohloka okushisayo kwe-HPMC kuthintwa yizici eziningi, kufaka phakathi:
Isakhiwo samakhemikhali: Izinga lokufaka esikhundleni se-hydroxypropyl kanye namaqembu we-methoxy ku-HPMC lithinta ukuqina kwalo okushisayo. Ngokuvamile, i-HPMC enokuqukethwe okuphezulu kwe-hydroxypropyl inokuqina okungcono okushisayo.
Isimo sezulu se-Ambient: Emoyeni, i-HPMC ithambekele ekuwohlokeni kwe-oxidative, ngenkathi isendaweni yegesi ye-inert (njenge-nitrogen), izinga laso lokuwohloka ashisayo lihamba kancane.
Isilinganiso sokushisa: Ukushisa okusheshayo kuzoholela ekuboleni okusheshayo, ngenkathi ukufudumala kancane kungasiza i-HPMC ukuthi ishelelezi kancane kancane futhi inciphise ukukhiqizwa kwemikhiqizo eguquguqukayo ye-gaseous.
Okuqukethwe umswakama: I-HPMC iqukethe inani elithile lamanzi aboshwe. Ngesikhathi senqubo yokufudumeza, ukuhwamuka komswakama kuzothinta izinga lokushisa lokushintsha kwengilazi nenqubo yokuwohloka.
Umthelela wohlelo lokusebenza olungokoqobo lokuwohloka okushisayo kwe-HPMC
Izici zokuwohloka kwe-thermalal ze-HPMC zibaluleke kakhulu kwinkambu yesicelo sayo. Ngokwesibonelo:
Imboni yezokwakha: I-HPMC isetshenziswa ku-Cement Datar kanye nemikhiqizo ye-gypsum, futhi ukuqina kwayo ngesikhathi sokwakhiwa okuphezulu kakhulu kufanele kubhekwe ukugwema ukonakala okuthinta ukusebenza kwe-bondar.
Imboni yezemithi: I-HPMC iyi-ejenti yokukhishwa kwezidakamizwa, futhi ukubola kufanele kugwenywe ngesikhathi sokukhiqizwa okushisa kakhulu ukuze kuqinisekiswe ukuqina kwesidakamizwa.
Imboni yokudla: I-HPMC isengezo sokudla, kanye nezici zayo zokuwohloka okushisayo kunquma ukusebenza kwayo ekubhaka okushisa kakhulu nokusebenza.
Inqubo yokuwohloka kwe-thermal yeI-HPMCIngahlukaniswa ngokuhwamuka kwamanzi kanye nokonakaliswa kokuqala esiteji sokushisa okuphansi, okuyi-main chain cleavation kanye nokuguquguquka kwama-molecule ezincane esigabeni sokushisa okuphakathi nendawo, kanye ne-carbonization kanye nokukhwehlela esiteji esishisa kakhulu. Ukuqina kwalo okushisayo kuthintwa yizinto ezifana nesakhiwo samakhemikhali, umkhathi okhona, isilinganiso sokushisa kanye nokuqukethwe komswakama. Ukuqonda indlela yokuwohloka kwe-thermal ye-HPMC kunenani elikhulu lokwandisa uhlelo lwayo futhi uthuthukise ukuqina ngokwezinto ezibonakalayo.
Isikhathi sePosi: Mar-28-2025