HPMC tswj cov viscosity ntawm cov txheej txheem

Hydroxypropyl Methylcellulose (HPMC)yog ib qho cellulose ether nonionic siv dav hauv cov ntaub ntawv tsim kho, coatings, tshuaj, khoom noj thiab lwm yam teb, tshwj xeeb tshaj yog hauv cov txheej txheem coatings vim nws cov khoom zoo heev thiab tshuaj lom neeg. HPMC ua lub luag haujlwm tseem ceeb hauv kev tswj cov viscosity ntawm coatings, thiab nws cov kev ua tau zoo thiab kev siv ua rau nws yog ib qho ntawm cov khoom ntxiv tsis tseem ceeb hauv kev lag luam coatings niaj hnub no.

HPMC muaj cov nyhuv ua kom tuab zoo. Nws tuaj yeem yaj sai hauv dej thiab tsim cov tshuaj colloidal sib xws, ua rau kom cov viscosity ntawm lub txheej txheem txheej. Qhov viscosity ntawm cov txheej yog ib qho tseem ceeb hauv kev txiav txim siab nws cov kev ua tau zoo hauv kev tsim kho, kev ruaj khov ntawm kev khaws cia thiab qhov zoo ntawm zaj duab xis. Los ntawm kev kho qhov ntau ntawm HPMC ntxiv, cov khoom rheological ntawm cov txheej tuaj yeem tswj tau qhov tseeb, yog li txhim kho kev txhuam, txheej txheej dov lossis kev txau thaum lub sijhawm tsim kho, yog li cov txheej tuaj yeem qhia tau tias muaj kev sib kis zoo thiab kev nplaum zoo hauv ntau txoj kev tsim kho, zam cov teeb meem xws li sagging thiab dripping.

HPMC muaj peev xwm kho qhov rheological zoo. Hauv lub txheej txheej, HPMC molecules tuaj yeem tsim cov qauv network, txhim kho cov qauv viscosity thiab cov txiaj ntsig ntawm lub kaw lus, ua rau cov txheej muaj viscosity siab dua hauv lub xeev static, thiab pab tiv thaiv kev sib sau ua ke ntawm cov xim thiab cov khoom sau; hauv lub xeev shear (xws li kev sib tov thiab txhuam), nws qhia txog kev ua haujlwm zoo shear thinning, txo viscosity, thiab pab txhawb kev ua haujlwm tsim kho. Cov cuab yeej rheological "pseudoplastic" no ua rau cov txheej txheej yooj yim dua rau kev thov, thiab viscosity tuaj yeem rov qab sai sai tom qab thov, uas yog qhov zoo rau qhov sib xws thiab tiaj tus ntawm zaj duab xis.

Lub zog thermal gelation ntawm HPMC kuj pab tswj qhov viscosity ntawm lub txheej. Thaum qhov kub nce siab, cov kua dej ntawm HPMC yuav qhia txog thermal gelation, uas yog qhov tshwj xeeb tshaj yog siv rau hauv qhov chaw tsim kho kub siab. Nws tuaj yeem tiv thaiv lub txheej kom tsis txhob muaj kua ntau dhau nyob rau hauv qhov kub siab mus rau qee qhov, yog li tswj tau qhov tuab ntawm lub txheej kom haum. Tsis tas li ntawd, HPMC muaj peev xwm khaws dej tau zoo, uas tuaj yeem txo qhov nrawm ntawm cov dej evaporation hauv lub txheej thaum lub sijhawm ziab, pab txhim kho qhov sib xws ntawm cov zaj duab xis txheej, thiab tiv thaiv kev tawg thiab tev tawm.

Qhov degree ntawm kev hloov pauv (DS) thiab molar hloov pauv (MS) ntawm HPMC kuj muaj qhov cuam tshuam tseem ceeb rau nws cov nyhuv thickening. HPMC nrog cov degree hloov pauv sib txawv ua txawv hauv solubility, viscosity ntawm cov kua, tsis kam ntsev thiab qhov kub thiab txias, yog li hom khoom HPMC tsim nyog tuaj yeem xaiv raws li cov kev cai tshwj xeeb ntawm cov txheej txheem. Piv txwv li, rau cov xim pleev xim latex sab hauv phab ntsa, qhov nruab nrab viscosity HPMC feem ntau raug xaiv kom tau txais kev txhuam zoo thiab cov khoom ua yeeb yaj kiab; thaum nyob rau hauv qee qhov kev ua tau zoo siab sab nraud phab ntsa xim, qhov siab viscosity HPMC tuaj yeem raug xaiv los txhim kho kev tiv thaiv kev sagging.

HPMC kuj tseem ua lub luag haujlwm zoo hauv kev ruaj khov ntawm cov xim thiab cov khoom sau. Los ntawm kev nce qhov viscosity ntawm lub kaw lus thiab tsim cov qauv ruaj khov peb-seem, HPMC tuaj yeem tiv thaiv kev sib sau ua ke thiab kev tso dej ntawm cov khoom me me, yog li txhim kho kev ruaj khov ntawm kev khaws cia ntawm cov txheej thiab txuas ntxiv nws lub neej txee. Qhov no tsis yog tsuas yog pab txhim kho kev siv cov khoom zoo, tab sis kuj txo qhov tshwm sim ntawm cov teeb meem zoo xws li delamination thiab agglomeration.

Ua ib qho khoom siv tseem ceeb hauv lub txheej txheem txheej,HPMCmuaj ntau qhov zoo hauv kev tswj hwm thiab tswj hwm qhov viscosity ntawm cov txheej: nws tsis tsuas yog muab cov tuab zoo tagnrho, tab sis kuj txhim kho kev ua haujlwm tsim kho thiab zoo ntawm zaj duab xis, thiab txhim kho kev ruaj khov cia thiab kev hloov pauv ib puag ncig ntawm cov txheej. Raws li cov kev xav tau ntawm kev lag luam txheej rau kev tiv thaiv ib puag ncig, kev ua haujlwm tsim kho thiab zoo ntawm cov zaj duab xis txheej txuas ntxiv nce ntxiv, cov kev cia siab ntawm daim ntawv thov ntawm HPMC yuav dav dua, thiab nws qhov tseem ceeb hauv cov qauv txheej yav tom ntej yuav dhau los ua qhov tseem ceeb.