Cov Yam Tseem Ceeb Uas Tswj Xyuas Kev Ruaj Ntseg ntawm Emulsions
Hauv kev siv ua haujlwm, qhov ruaj khov ntawm cov emulsion yog hais txog lub peev xwm ntawm cov dej ntws uas tawg ua tej daim me me kom tiv taus kev sib sau ua ke. Ntawm cov ntsuas rau kev ntsuas qhov ruaj khov ntawm emulsion, qhov nrawm ntawm kev sib sau ua ke ntawm cov dej ntws uas tawg ua tej daim me me yog qhov tseem ceeb heev; nws tuaj yeem txiav txim siab los ntawm kev ntsuas seb tus lej ntawm cov dej ntws ib chav ntim hloov pauv li cas dhau sijhawm. Thaum cov dej ntws hauv cov emulsion sib koom ua ke rau hauv cov loj dua thiab thaum kawg ua rau tawg, qhov ceev ntawm cov txheej txheem no nyob ntawm cov hauv qab no: cov khoom siv lub cev ntawm zaj duab xis interfacial, electrostatic repulsion ntawm cov dej ntws, steric hindrance los ntawm cov zaj duab xis polymer, viscosity ntawm theem txuas ntxiv mus, qhov loj me ntawm cov dej ntws thiab kev faib tawm, qhov sib piv ntawm theem ntim, kub, thiab lwm yam.
Ntawm cov no, qhov xwm txheej ntawm zaj duab xis interfacial, kev sib cuam tshuam hluav taws xob, thiab kev cuam tshuam steric yog qhov tseem ceeb tshaj plaws.
(1) Cov Khoom Siv Lub Cev ntawm Zaj Duab Xis Interfacial
Kev sib tsoo ntawm cov tee dej uas tawg ua ntu zus yog qhov yuav tsum tau ua ua ntej rau kev sib koom ua ke. Kev sib koom ua ke txuas ntxiv mus tas li, ua rau cov tee dej me me me mus ua cov loj dua kom txog thaum cov emulsion tawg. Thaum lub sijhawm sib tsoo thiab sib koom ua ke, lub zog kho tshuab ntawm cov yeeb yaj kiab interfacial ntawm cov tee dej sawv cev rau qhov tseem ceeb tshaj plaws ntawm kev ruaj khov ntawm emulsion. Yuav kom muab cov yeeb yaj kiab interfacial nrog lub zog kho tshuab loj, nws yuav tsum yog cov yeeb yaj kiab sib xws - nws cov tshuaj surfactant sib xyaw ua ke los ntawm cov zog sab nraud muaj zog. Cov yeeb yaj kiab kuj yuav tsum muaj qhov elasticity zoo, yog li thaum muaj kev puas tsuaj hauv zos los ntawm kev sib tsoo ntawm cov tee dej, nws tuaj yeem kho nws tus kheej.
(2) Kev Sib Cuam Tshuam Hluav Taws Xob
Cov dej ntws hauv cov emulsions yuav tau txais qee qhov nqi rau ntau yam laj thawj: ionization ntawm ionic surfactants, adsorption ntawm cov ions tshwj xeeb rau ntawm qhov chaw ntawm cov dej ntws, kev sib txhuam ntawm cov dej ntws thiab cov khoom nruab nrab, thiab lwm yam. Hauv cov roj-hauv-dej (O/W) emulsions, kev them cov dej ntws ua lub luag haujlwm tseem ceeb hauv kev tiv thaiv kev sib sau ua ke, kev sib koom ua ke, thiab kev tawg thaum kawg. Raws li kev ruaj khov colloid, van der Waals forces rub cov dej ntws ua ke; tsis tau thaum cov dej ntws los ze txaus rau lawv cov txheej ob sab kom sib tshooj, electrostatic repulsion cuam tshuam kev sib ze ntxiv. Nws yog qhov tseeb, yog tias kev sib koom ua ke ntau dua li qhov nyiam, cov dej ntws tsis tshua muaj feem sib tsoo thiab sib sau ua ke, thiab cov emulsion tseem ruaj khov; txwv tsis pub, kev sib koom ua ke thiab kev tawg ua rau muaj.
Raws li cov dej-hauv-roj (W/O) emulsions, cov dej tee dej nqa me ntsis xwb, thiab vim tias cov theem tas mus li muaj qhov dielectric tsis tu ncua thiab ob txheej tuab, cov teebmeem electrostatic tsuas yog muaj kev cuam tshuam me ntsis rau kev ruaj khov.
(3) Kev Ruaj Ntseg Steric
Thaum cov polymers ua haujlwm ua cov emulsifiers, cov txheej interfacial yuav tuab dua, tsim ib lub lyophilic tiv thaiv nyob ib puag ncig txhua lub tee dej - ib qho chaw thaiv uas tiv thaiv cov tee dej los ntawm kev kos ze thiab ua kev sib cuag. Lub xwm txheej lyophilic ntawm cov polymer molecules kuj ntes tau ntau cov kua dej txuas ntxiv mus rau hauv cov txheej tiv thaiv, ua rau nws zoo li gel. Yog li ntawd, thaj chaw interfacial qhia txog kev sib xyaw ua ke ntawm cov interfacial viscosity thiab viscoelasticity zoo, uas pab tiv thaiv cov tee dej sib xyaw thiab khaws cia kev ruaj khov. Txawm tias qee qhov kev sib koom ua ke tshwm sim, cov polymer emulsifiers feem ntau sib sau ua ke ntawm qhov sib koom ua ke hauv cov ntaub ntawv fibrous lossis crystalline, ua rau cov zaj duab xis interfacial tuab thiab yog li ntawd tiv thaiv kev sib koom ua ke ntxiv.
(4) Kev sib npaug ntawm qhov loj ntawm cov tee dej faib tawm
Thaum ib qho ntim ntawm cov theem tawg tau tawg ua cov tee dej ntawm ntau qhov ntau thiab tsawg, lub kaw lus uas muaj cov tee dej loj dua muaj thaj chaw sib tshuam me dua thiab yog li ntawd lub zog sib tshuam qis dua, muab kev ruaj khov thermodynamic ntau dua. Hauv cov emulsion uas cov tee dej ntawm ob qho tib si loj thiab me me sib koom ua ke, cov tee dej me me feem ntau yuav ntsws thaum cov loj loj loj hlob. Yog tias qhov kev nce qib no txuas ntxiv mus tsis tau tswj hwm, kev tawg yuav tshwm sim thaum kawg. Yog li ntawd, cov emulsion nrog qhov faib tawm ntawm cov tee dej nqaim, sib npaug yog ruaj khov dua li ib qho uas qhov nruab nrab ntawm cov tee dej loj yog tib yam tab sis nws qhov loj me yog dav.
(5) Kev cuam tshuam ntawm Kub
Qhov kub thiab txias hloov pauv tuaj yeem hloov pauv qhov sib zog ntawm cov khoom sib xyaw, cov yam ntxwv thiab viscosity ntawm cov zaj duab xis sib xyaw, qhov sib piv ntawm cov emulsifier hauv ob theem, lub zog vapor ntawm cov kua theem, thiab kev txav thermal ntawm cov dej ntws tawm. Tag nrho cov kev hloov pauv no tuaj yeem cuam tshuam rau kev ruaj khov ntawm emulsion thiab tej zaum yuav ua rau theem tig rov qab lossis tawg.
Lub sijhawm tshaj tawm: Kaum Ib Hlis-27-2025