Hydroxyethyl cellulose (HEC) yog ib qho polymer uas tsis yog ionic, uas yaj tau hauv dej los ntawm cellulose los ntawm kev hloov kho tshuaj lom neeg. Nws pom tias siv dav hauv ntau yam lag luam vim nws cov khoom tshwj xeeb, xws li thickening, stabilizing, thiab zaj duab xis-ua peev xwm. Hauv cov ntawv thov uas pH stability tseem ceeb heev, kev nkag siab txog HEC ua li cas nyob rau hauv cov xwm txheej pH sib txawv yog qhov tseem ceeb.
Qhov pH ruaj khov ntawm HEC hais txog nws lub peev xwm los tswj nws cov qauv kev ncaj ncees, cov khoom rheological, thiab kev ua tau zoo thoob plaws ntau yam pH ib puag ncig. Qhov kev ruaj khov no yog qhov tseem ceeb hauv cov ntawv thov xws li cov khoom siv tu tus kheej, tshuaj, coatings, thiab cov ntaub ntawv tsim kho, qhov twg pH ntawm ib puag ncig ib puag ncig tuaj yeem hloov pauv ntau.
Qauv:
HEC feem ntau yog tsim los ntawm kev sib xyaw cellulose nrog ethylene oxide nyob rau hauv alkaline tej yam kev mob. Cov txheej txheem no ua rau muaj kev hloov pauv ntawm cov hydroxyl pawg ntawm cellulose backbone nrog hydroxyethyl (-OCH2CH2OH) pawg. Qhov degree ntawm kev hloov pauv (DS) qhia txog tus lej nruab nrab ntawm cov hydroxyethyl pawg ib chav tsev anhydroglucose hauv cov saw cellulose.
Cov Khoom:
Kev yaj: HEC yaj tau hauv dej thiab tsim cov tshuaj ntshiab, khov kho.
Viscosity: Nws qhia txog pseudoplastic lossis shear-thinning tus cwj pwm, txhais tau tias nws cov viscosity txo qis hauv qab kev ntxhov siab shear. Cov yam ntxwv no ua rau nws muaj txiaj ntsig zoo rau cov ntawv thov uas qhov ntws tseem ceeb, xws li xim thiab txheej.
Thickening: HEC imparts viscosity rau cov kev daws teeb meem, ua rau nws muaj nqis ua tus neeg sawv cev thickening hauv ntau yam formulations.
Kev tsim zaj duab xis: Nws tuaj yeem tsim cov zaj duab xis uas yoog tau thiab pob tshab thaum qhuav, uas yog qhov zoo rau cov ntawv thov xws li cov nplaum thiab cov txheej txheem.
pH Stability ntawm HEC
Qhov pH stability ntawm HEC yog cuam tshuam los ntawm ntau yam, suav nrog cov qauv tshuaj ntawm cov polymer, kev sib cuam tshuam nrog ib puag ncig ib puag ncig, thiab txhua yam additives muaj nyob rau hauv cov formulation.
Kev ruaj khov pH ntawm HEC hauv ntau yam pH sib txawv:
1. pH uas muaj kua qaub:
Ntawm cov kua qaub pH, HEC feem ntau ruaj khov tab sis tej zaum yuav raug hydrolysis ntev dua nyob rau hauv cov mob acidic hnyav. Txawm li cas los xij, hauv feem ntau cov ntawv thov, xws li cov khoom siv tu tus kheej thiab cov txheej txheem, qhov twg acidic pH ntsib, HEC tseem ruaj khov hauv qhov pH ib txwm muaj (pH 3 txog 6). Tshaj li pH 3, qhov kev pheej hmoo ntawm hydrolysis nce ntxiv, ua rau maj mam txo qis hauv viscosity thiab kev ua tau zoo. Nws yog ib qho tseem ceeb los saib xyuas pH ntawm cov formulations uas muaj HEC thiab kho lawv raws li qhov tsim nyog kom tswj tau qhov ruaj khov.
2. pH nruab nrab:
HEC qhia tau tias muaj kev ruaj khov zoo heev nyob rau hauv cov xwm txheej pH nruab nrab (pH 6 txog 8). Qhov pH no yog ib qho uas siv ntau hauv ntau daim ntawv thov, suav nrog cov tshuaj pleev ib ce, tshuaj, thiab cov khoom siv hauv tsev. Cov qauv uas muaj HEC khaws lawv cov viscosity, cov khoom tuab, thiab kev ua tau zoo tag nrho hauv qhov pH no. Txawm li cas los xij, cov yam xws li kub thiab lub zog ionic tuaj yeem cuam tshuam rau kev ruaj khov thiab yuav tsum tau xav txog thaum lub sijhawm tsim cov qauv.
3. pH Alkaline:
HEC tsis ruaj khov nyob rau hauv alkaline mob piv rau acidic lossis neutral pH. Ntawm cov pH siab (saum pH 8), HEC yuav raug degradation, ua rau txo qis viscosity thiab poob ntawm kev ua tau zoo. Alkaline hydrolysis ntawm ether linkages ntawm cellulose backbone thiab hydroxyethyl pawg tuaj yeem tshwm sim, ua rau saw hlau scission thiab txo qhov hnyav molecular. Yog li ntawd, nyob rau hauv alkaline formulations xws li detergents lossis cov ntaub ntawv tsim kho, lwm cov polymers lossis stabilizers yuav raug nyiam dua HEC.
Cov Yam Cuam Tshuam Rau Kev Ruaj Ntseg pH
Muaj ntau yam uas yuav cuam tshuam rau qhov pH stability ntawm HEC:
Qib Kev Hloov Chaw (DS): HEC nrog cov nqi DS siab dua feem ntau yuav ruaj khov dua thoob plaws ntau yam pH vim muaj kev hloov pauv ntawm cov pab pawg hydroxyl nrog cov pab pawg hydroxyethyl, uas ua rau cov dej solubility thiab tiv taus hydrolysis.
Kub: Qhov kub siab tuaj yeem ua rau cov tshuaj lom neeg ua haujlwm sai dua, suav nrog hydrolysis. Yog li ntawd, kev tswj hwm qhov kub thiab txias kom zoo yog qhov tseem ceeb rau kev tswj hwm qhov pH ruaj khov ntawm cov qauv uas muaj HEC.
Lub Zog Ionic: Cov ntsev lossis lwm yam ions ntau hauv cov qauv tuaj yeem cuam tshuam rau kev ruaj khov ntawm HEC los ntawm kev cuam tshuam rau nws cov solubility thiab kev sib cuam tshuam nrog cov dej molecules. Lub zog Ionic yuav tsum tau ua kom zoo tshaj plaws kom txo qis cov teebmeem tsis ruaj khov.
Cov Khoom Ntxiv: Kev siv cov khoom ntxiv xws li surfactants, preservatives, lossis buffering agents tuaj yeem cuam tshuam rau pH stability ntawm HEC formulations. Kev sim sib xws yuav tsum tau ua kom ntseeg tau tias cov khoom ntxiv sib xws thiab ruaj khov.
Cov Kev Siv thiab Kev Xav Txog Kev Tsim Qauv
Kev nkag siab txog qhov ruaj khov ntawm HEC yog qhov tseem ceeb rau cov neeg tsim khoom hauv ntau yam lag luam.
Nov yog qee qhov kev xav txog rau daim ntawv thov:
Cov Khoom Siv Kho Mob Tus Kheej: Hauv cov tshuaj zawv plaub hau, cov tshuaj pleev, thiab cov tshuaj pleev, tswj cov pH hauv qhov ntau yam xav tau (feem ntau nyob ib puag ncig nruab nrab) ua kom muaj kev ruaj khov thiab kev ua tau zoo ntawm HEC ua tus neeg sawv cev thickening thiab suspending.
Cov Tshuaj: HEC siv rau hauv cov tshuaj haus, cov tshuaj pleev qhov muag, thiab cov tshuaj pleev rau sab nraud. Cov tshuaj yuav tsum tau tsim thiab khaws cia rau hauv cov xwm txheej uas khaws cia HEC kom ruaj khov kom ntseeg tau tias cov khoom siv tau zoo thiab lub neej txee.
Cov Txheej Txheem thiab Xim: HEC yog siv los ua tus hloov pauv rheology thiab thickener hauv cov xim thiab cov txheej txheem dej. Cov neeg tsim qauv yuav tsum sib npaug pH cov kev cai nrog lwm cov qauv kev ua tau zoo xws li viscosity, leveling, thiab zaj duab xis tsim.
Cov Khoom Siv Tsim Kho: Hauv cov qauv cementitious, HEC ua haujlwm ua tus neeg sawv cev khaws dej thiab txhim kho kev ua haujlwm. Txawm li cas los xij, cov xwm txheej alkaline hauv cement tuaj yeem ua rau HEC ruaj khov, xav tau kev xaiv thiab kev hloov kho cov qauv kom zoo.
Hydroxyethyl cellulose (HEC) muaj cov khoom siv rheological thiab kev ua haujlwm zoo hauv ntau yam kev siv. Kev nkag siab txog nws qhov pH stability yog qhov tseem ceeb rau cov formulators los tsim cov formulations ruaj khov thiab zoo. Thaum HEC qhia tau tias muaj kev ruaj khov zoo nyob rau hauv cov xwm txheej pH nruab nrab, yuav tsum xav txog rau cov chaw acidic thiab alkaline kom tiv thaiv kev puas tsuaj thiab xyuas kom meej tias muaj kev ua tau zoo tshaj plaws. Los ntawm kev xaiv qib HEC tsim nyog, kev ua kom zoo dua cov qauv tsim, thiab kev siv cov xwm txheej cia khoom tsim nyog, cov formulators tuaj yeem siv cov txiaj ntsig ntawm HEC thoob plaws ntau yam pH ib puag ncig.
Lub sijhawm tshaj tawm: Lub Peb Hlis-29-2024