I-Hydroxypropylmethylcellulose (HPMC) iyinhlanganisela esibe yinto eyinhloko ezimbonini eziningi ngenxa yezakhiwo zayo eziningi zokusebenza. Ivame ukusetshenziswa njengesithako sokudla, isithako esijiyile ezimonyweni, ngisho nesithako sezokwelapha emithini eminingi. Impahla eyingqayizivele ye-HPMC ukuziphatha kwayo kwe-thixotropic, okuyivumela ukuthi ishintshe izakhiwo ze-viscosity kanye nokugeleza ngaphansi kwezimo ezithile. Ngaphezu kwalokho, kokubili i-HPMC ene-viscosity ephezulu kanye ne-viscosity ephansi inale mpahla, ikhombisa i-thixotropy ngisho nangaphansi kwezinga lokushisa lejeli.
I-Thixotropy yenzeka ku-HPMC lapho isixazululo siba sincane uma kufakwa ingcindezi noma kuhlanganiswa, okuholela ekunciphiseni i-viscosity. Lokhu kuziphatha kungabuye kuguqulwe; lapho ingcindezi isuswa futhi isixazululo sishiywa siphumule, i-viscosity ibuyela kancane esimweni sayo esiphezulu. Lesi sici esiyingqayizivele senza i-HPMC ibe yingxenye ebalulekile ezimbonini eziningi njengoba ivumela ukusetshenziswa okubushelelezi kanye nokucutshungulwa okulula.
Njenge-hydrocolloid engeyona i-ionic, i-HPMC iyavuvukala emanzini ukuze yakhe ijeli. Izinga lokuvuvukala kanye ne-gelling lincike esisindweni sama-molecule kanye nokuhlushwa kwe-polymer, i-pH kanye nokushisa kwesisombululo. I-HPMC e-viscosity ephezulu ngokuvamile inesisindo sama-molecule aphezulu futhi ikhiqiza ijeli e-viscosity ephezulu, kuyilapho i-HPMC e-viscosity ephansi inesisindo sama-molecule esiphansi futhi ikhiqiza ijeli e-viscous encane. Kodwa-ke, naphezu kwalokhu kungafani ekusebenzeni, zombili izinhlobo ze-HPMC zibonisa i-thixotropy ngenxa yezinguquko zesakhiwo ezenzeka ezingeni lama-molecule.
Ukuziphatha kwe-thixotropic kwe-HPMC kuwumphumela wokuqondana kwamaketanga e-polymer ngenxa yokucindezeleka kwe-shear. Lapho ukucindezeleka kwe-shear kusetshenziswa ku-HPMC, amaketanga e-polymer aqondana ngendlela yokucindezeleka okusetshenzisiwe, okuholela ekubhujisweni kwesakhiwo senethiwekhi esinezinhlangothi ezintathu esasikhona lapho kungekho ukucindezeleka. Ukuphazamiseka kwenethiwekhi kuphumela ekunciphiseni kwe-viscosity yesisombululo. Lapho ukucindezeleka kususwa, amaketanga e-polymer ahlelwa kabusha ngendlela yawo yokuqala, akhe kabusha inethiwekhi futhi abuyisele i-viscosity.
I-HPMC iphinde ibonise i-thixotropy ngaphansi kwezinga lokushisa le-gelling. Izinga lokushisa le-gel yizinga lokushisa lapho amaketanga e-polymer ehlangana khona ukuze akhe inethiwekhi enezinhlangothi ezintathu, akha i-gel. Kuncike ekugxilweni, isisindo sama-molecule kanye ne-pH yesisombululo se-polymer. I-gel ephumayo ine-viscosity ephezulu futhi ayishintshi ngokushesha ngaphansi kwengcindezi. Kodwa-ke, ngaphansi kwezinga lokushisa le-gelation, isixazululo se-HPMC sahlala simanzi, kodwa sisabonisa ukuziphatha kwe-thixotropic ngenxa yokuba khona kwesakhiwo senethiwekhi esakhiwe kancane. Inethiwekhi eyakhiwe yilezi zingxenye iyawohloka ngaphansi kwengcindezi, okuholela ekunciphiseni kwe-viscosity. Lokhu kuziphatha kuyasiza ezisetshenzisweni eziningi lapho izixazululo zidinga ukugeleza kalula lapho zixutshwa.
I-HPMC iyikhemikhali eguquguqukayo enezakhiwo eziningana ezihlukile, enye yazo ukuziphatha kwayo kwe-thixotropic. Zombili i-HPMCs ezinokuqina okuphezulu kanye nokuqina okuphansi zinalesi sici, zibonisa i-thixotropy ngisho nangaphansi kokushisa kwejeli. Lesi sici senza i-HPMC ibe yingxenye ebalulekile ezimbonini eziningi ezidinga izixazululo ezisingatha ukugeleza okulula ukuqinisekisa ukusetshenziswa okubushelelezi. Naphezu komehluko wezakhiwo phakathi kwe-HPMCs ezinokuqina okuphezulu kanye nokuqina okuphansi, ukuziphatha kwazo kwe-thixotropic kwenzeka ngenxa yokuqondaniswa kanye nokuphazamiseka kwesakhiwo senethiwekhi esakhiwe kancane. Ngenxa yezakhiwo zayo ezihlukile, abacwaningi bahlala behlola izinhlelo zokusebenza ezahlukahlukene ze-HPMC, benethemba lokudala imikhiqizo emisha futhi banikeze izixazululo ezingcono kubathengi emhlabeni jikelele.
Isikhathi sokuthunyelwe: Agasti-23-2023