Iyini i-Hydroxypropyl Methylcellulose Yenziwe Nga?

I-Hydroxypropyl methylcellulose (HPMC) iyi-polymer ye-semisynthetic esetshenziswa ezinhlobonhlobo zezimboni, ezihlanganisa ezokwakha, ukudla, imithi, kanye nemikhiqizo yokunakekelwa komuntu siqu. Yaziswa ngekhono layo lokuthuthukisa izakhiwo ze-rheological zokwakheka, kanye nokuhambisana kwayo nezinye izithako kanye nobuthi bayo obuphansi. Ukuze uqonde ukuthi i-HPMC yenziwa kanjani, kubalulekile ukuqonda kuqala isakhiwo kanye nezakhiwo ze-cellulose.

I-Cellulose iyiketango elide lama-molecule e-glucose atholakala ezindongeni zamangqamuzana ezitshalo. Ama-molecule e-glucose axhunywe ndawonye ngamabhondi e-beta-1,4-glycosidic, akhe iketango eliwumugqa. Lamaketango abe esehlanganiswa ndawonye ngamabhondi e-hydrogen kanye namandla ka-Van der Waals akhe izakhiwo eziqinile, ezinemicu. I-Cellulose iyinhlanganisela yezinto eziphilayo egcwele kakhulu emhlabeni, futhi isetshenziswa ezinhlobonhlobo zezinhlelo zokusebenza, kuhlanganise nephepha, izindwangu, nezinto zokwakha.

Nakuba i-cellulose inezinto eziningi eziwusizo, imvamisa iqinile futhi ayincibiliki ukuze isetshenziswe ekwenziweni okuningi. Ukuze banqobe le mikhawulo, ososayensi basungule okuphuma kokunye okuguquliwe kwe-cellulose, okuhlanganisa ne-HPMC. I-HPMC yenziwa ngokushintsha i-cellulose yemvelo ngochungechunge lokusabela kwamakhemikhali.

Isinyathelo sokuqala sokwenza i-HPMC ukuthola impahla yokuqala ye-cellulose. Lokhu kungenziwa ngokukhipha i-cellulose emithonjeni yezitshalo efana ne-wood pulp, ukotini, noma uqalo. I-cellulose ibe isiphathwa ngesisombululo se-alkaline, njenge-sodium hydroxide noma i-potassium hydroxide, ukuze kukhishwe ukungcola futhi kuphule imicu ye-cellulose ibe izinhlayiya ezincane. Le nqubo yaziwa ngokuthi i-mercerization, futhi yenza i-cellulose isebenze kakhulu futhi kube lula ukuyilungisa.

Ngemuva kwe-mercerization, i-cellulose isabela ngengxube ye-propylene oxide ne-methyl chloride ukwethula i-hydroxypropyl namaqembu e-methyl kumgogodla we-cellulose. Amaqembu e-hydroxypropyl engeziwe ukuze kuthuthukiswe ukuncibilika nokugcinwa kwamanzi kwezakhi ze-cellulose, kuyilapho amaqembu e-methyl engezwa ukuze kwandiswe ukuzinza nokunciphisa ukusebenza kabusha kwe-cellulose. Ukusabela ngokuvamile kwenziwa phambi kwe-catalyst, njenge-sodium hydroxide noma i-potassium hydroxide, nangaphansi kwezimo ezilawulwayo zokushisa, ingcindezi, nesikhathi sokuphendula.

I-degree of substitution (DS) ye-HPMC ibhekisela enanini le-hydroxypropyl namaqembu e-methyl angeniswa kumgogodla we-cellulose. I-DS ingahluka kuye ngezici ezifiswayo ze-HPMC kanye nohlelo oluthile esetshenziselwa lona. Ngokuvamile, amanani aphezulu e-DS aphumela ku-HPMC ene-viscosity ephansi namazinga okuphela okusheshayo, kuyilapho amanani aphansi e-DS ephumela ku-HPMC ene-viscosity ephezulu kanye namazinga ancibilikayo ahamba kancane.

Ngemuva kokuthi ukusabela kuqediwe, umkhiqizo owumphumela uyahlanzwa futhi womiswe ukuze udale i-HPMC powder. Inqubo yokuhlanza ibandakanya ukususa noma imaphi amakhemikhali angaphenduliwe, izincibilikisi ezisalela, nokunye ukungcola ku-HPMC. Lokhu ngokuvamile kwenziwa ngenhlanganisela yezinyathelo zokugeza, zokuhlunga, nokomisa.

Umkhiqizo wokugcina uyimpushana emhlophe ukuya kokumhlophe engenaphunga futhi engenambitheki. I-HPMC iyancibilika emanzini kanye nezincibilikisi eziningi eziphilayo, futhi ingakha amajeli, amafilimu, nezinye izakhiwo kuye ngezimo zokusetshenziswa. I-polymer engeyona i-ionic, okusho ukuthi ayithwali noma iyiphi ishaji kagesi, futhi ngokuvamile ibhekwa njengengenabo ubuthi futhi iphephile ukusetshenziswa kuhlelo olubanzi lwezinhlelo zokusebenza.

I-HPMC isetshenziswa ezinhlobonhlobo zokwakheka, okuhlanganisa upende, izinto ezinamathelayo, ama-sealants, imithi, nemikhiqizo yokudla. Ezicelweni zokwakha, i-HPMC ivamise ukusetshenziswa njenge-thickener, binder, kanye nefilimu-yangaphambili emikhiqizweni esekwe usimende ne-gypsum, efana nodaka, ama-grouts, nezinhlanganisela ezihlanganyelwe.