IHydroxypropyl methylcellulose (HPMC) iyi-ether engeyona ionic cellulose esetshenziswa kakhulu kwezokwelapha, ukudla, ukwakhiwa nakweminye imikhakha, ikakhulukazi kumaphilisi akhishwa ngokuqhubekayo izidakamizwa nezinto zokwakha. Ucwaningo lokuwohloka kokushisa kwe-HPMC alubalulekile nje kuphela ekuqondeni izinguquko zokusebenza okungenzeka kuhlangatshezwane nazo ngesikhathi sokucutshungulwa, kodwa futhi lubaluleke kakhulu ekwenzeni izinto ezintsha kanye nokwenza ngcono impilo yesevisi nokuphepha kwemikhiqizo.
Izici zokuwohloka kokushisa kwe-HPMC
Ukuwohloka okushisayo kwe-hydroxypropyl methylcellulose kuthinteka kakhulu ukwakheka kwayo kwamangqamuzana, izinga lokushisa lokushisa kanye nezimo zayo zemvelo (njengomkhathi, umswakama, njll.). Isakhiwo sayo samangqamuzana siqukethe inani elikhulu lamaqembu e-hydroxyl kanye nezibopho ze-ether, ngakho-ke ijwayele ukusabela kwamakhemikhali njenge-oxidation kanye nokubola emazingeni okushisa aphezulu.
Inqubo yokuwohloka kokushisa kwe-HPMC imvamisa ihlukaniswe izigaba ezimbalwa. Okokuqala, emazingeni okushisa aphansi (mayelana ne-50-150 ° C), i-HPMC ingase ilahlekelwe isisindo ngenxa yokulahlekelwa kwamanzi amahhala namanzi adsorbed, kodwa le nqubo ayibandakanyi ukuphulwa kwezibopho zamakhemikhali, izinguquko zomzimba kuphela. Njengoba izinga lokushisa likhuphuka ngokuqhubekayo (ngaphezu kuka-150 ° C), izibopho ze-ether namaqembu e-hydroxyl esakhiweni se-HPMC aqala ukuphuka, okuholela ekuqhekekeni kweketango lamangqamuzana kanye nezinguquko esakhiweni. Ngokukhethekile, lapho i-HPMC ishiselwa cishe ku-200-300 ° C, iqala ukubola okushisayo, ngaleso sikhathi amaqembu e-hydroxyl namaketango aseceleni afana ne-methoxy noma i-hydroxypropyl ku-molecule kancane kancane abola ukuze akhiqize imikhiqizo emincane yamangqamuzana njenge-methanol, i-formic. i-asidi kanye nenani elincane lama-hydrocarbons.
Indlela yokuwohloka kokushisa
Indlela yokuwohloka kwe-thermal ye-HPMC iyinkimbinkimbi futhi ibandakanya izinyathelo eziningi. Indlela yayo yokucekela phansi ingafingqwa kanje: njengoba izinga lokushisa likhuphuka, amabhondi e-ether ku-HPMC aphuka kancane kancane ukuze akhiqize izingcezwana zamangqamuzana, abe esebola nakakhulu ukuze akhiphe imikhiqizo yegesi njengamanzi, i-carbon dioxide, ne-carbon monoxide. Izindlela zayo eziyinhloko zokuwohloka kwe-thermal zihlanganisa lezi zinyathelo ezilandelayo:
Inqubo yokuphelelwa amanzi emzimbeni: I-HPMC ilahlekelwa amanzi adsorbed ngokomzimba kanye nenani elincane lamanzi abophekile ekushiseni okuphansi, futhi le nqubo ayibhubhisi isakhiwo sayo samakhemikhali.
Ukuwohloka kwamaqembu e-hydroxyl: Ezingeni lokushisa elingaba ngu-200-300°C, amaqembu e-hydroxyl ochungechungeni lwamangqamuzana e-HPMC aqala uku-pyrolyze, akhiqize amanzi nama-hydroxyl radicals. Ngalesi sikhathi, amaketanga aseceleni e-methoxy ne-hydroxypropyl nawo ayabola kancane kancane ukuze akhiqize ama-molecule amancane njenge-methanol, i-formic acid, njll.
Ukuphuka kweketango eliyinhloko: Uma izinga lokushisa liqhubeka likhuphuka libe ngu-300-400 ° C, izibopho ze-β-1,4-glycosidic zeketango eliyinhloko le-cellulose zizokwenziwa i-pyrolysis ukuze kukhiqizwe imikhiqizo emincane eguquguqukayo nezinsalela zekhabhoni.
Okunye ukuqhekeka: Lapho izinga lokushisa likhuphuka lifinyelela ngaphezu kuka-400°C, ama-hydrocarbon asele nezinye izingcezwana ze-cellulose ezonakaliswe ngokuqhubekayo kuzodala i-CO2, i-CO kanye nezinye izinto ezincane ze-organic molecule.
Izinto ezithinta ukuwohloka kokushisa
Ukuwohloka kokushisa kwe-HPMC kuthintwa izici eziningi, ikakhulukazi ezihlanganisa izici ezilandelayo:
Izinga lokushisa: Izinga nezinga lokuwohloka kokushisa kuhlobene eduze nezinga lokushisa. Ngokuvamile, izinga lokushisa liphakeme, ukusabela kokuwohloka kuyashesha futhi kuyanda izinga lokuwohloka. Kuzinhlelo zokusebenza ezingokoqobo, indlela yokulawula izinga lokushisa lokucubungula ukuze ugweme ukuwohloka okweqile kokushisa kwe-HPMC kuyindaba edinga ukunakwa.
I-Atmosphere: Ukuziphatha kokuwohloka kokushisa kwe-HPMC ezindaweni ezihlukene nakho kuhlukile. Emoyeni noma endaweni ye-oksijini, i-HPMC kulula ukwenza i-oxidize, ikhiqize imikhiqizo eminingi enegesi nezinsalela zekhabhoni, kuyilapho endaweni engenalutho (njenge-nitrogen), inqubo yokuwohloka ibonakala ngokuyinhloko njenge-pyrolysis, ikhiqiza inani elincane lezinsalela zekhabhoni.
Isisindo samangqamuzana: Isisindo samangqamuzana e-HPMC siphinde sithinte ukuziphatha kwayo kokuwohloka kokushisa. Ukuphakama kwesisindo samangqamuzana, izinga lokushisa lokuqala lokuwohloka kokushisa liphezulu. Lokhu kungenxa yokuthi i-HPMC enesisindo esikhulu samangqamuzana inamaketanga amamolekyuli amade kanye nezakhiwo ezizinzile, futhi idinga amandla aphezulu ukuze iphule izibopho zayo zamangqamuzana.
Okuqukethwe umswakama: Okuqukethwe umswakama ku-HPMC nakho kuthinta ukuwohloka kwayo kokushisa. Umswakama unganciphisa izinga lokushisa kwawo lokubola, okuvumela ukuwohloka ukuba kwenzeke emazingeni okushisa aphansi.
Umthelela wohlelo lokuwohloka kokushisa
Izici zokuwohloka kokushisa kwe-HPMC zinomthelela obalulekile ekusebenzeni kwayo okungokoqobo. Isibonelo, emalungiselelweni emithi, i-HPMC ivamise ukusetshenziswa njengento ekhishwa njalo ukulawula izinga lokukhishwa kwezidakamizwa. Nokho, ngesikhathi sokucubungula izidakamizwa, amazinga okushisa aphezulu azothinta ukwakheka kwe-HPMC, ngaleyo ndlela aguqule ukusebenza kokukhululwa komuthi. Ngakho-ke, ukutadisha ukuziphatha kwayo kokuwohloka kokushisa kubaluleke kakhulu ekuthuthukiseni ukucutshungulwa kwezidakamizwa nokuqinisekisa ukuzinza kwezidakamizwa.
Ezimpahleni zokwakha, i-HPMC isetshenziswa kakhulu emikhiqizweni yokwakha efana nosimende negypsum ukuze ibambe iqhaza ekujikeni nasekugcineni amanzi. Njengoba izinto zokwakha ngokuvamile zidinga ukuhlangabezana nezimo zokushisa eziphezulu lapho zisetshenziswa, ukuzinza okushisayo kwe-HPMC nakho kuwukucatshangelwa okubalulekile ekukhethweni kwezinto ezibonakalayo. Emazingeni okushisa aphezulu, ukuwohloka kokushisa kwe-HPMC kuzoholela ekwehleni kokusebenza kwempahla, ngakho-ke lapho ukhetha futhi uyisebenzisa, ukusebenza kwayo emazingeni okushisa ahlukene kuvame ukucatshangelwa.
Inqubo ye-thermal degradation ye-hydroxypropyl methylcellulose (HPMC) ihlanganisa izinyathelo eziningi, ezithinteka kakhulu izinga lokushisa, umoya, isisindo samangqamuzana kanye nomswakama. Indlela yayo yokuwohloka kokushisa ihilela ukuphelelwa amanzi emzimbeni, ukubola kwe-hydroxyl namaketango aseceleni, kanye nokuqhekeka kweketango eliyinhloko. Izici zokuwohloka kokushisa okushisayo kwe-HPMC zinokubaluleka kokusetshenziswa okubalulekile emikhakheni yamalungiselelo emithi, izinto zokwakha, njll. Ngakho-ke, ukuqonda okujulile kokuziphatha kwayo kokonakala okushisayo kubalulekile ekuthuthukiseni inqubo yokuklama kanye nokwenza ngcono ukusebenza komkhiqizo. Ocwaningweni oluzayo, ukuzinza okushisayo kwe-HPMC kungathuthukiswa ngokuguqulwa, ukwengeza iziqinisi, njll., ngaleyo ndlela kwandiswe inkambu yohlelo lokusebenza.
Isikhathi sokuthumela: Oct-25-2024