Qhov txawv ntawm HEC thiab EC

HEC thiab EC yog ob hom cellulose ethers nrog cov khoom sib txawv thiab kev siv. HEC sawv cev rau hydroxyethyl cellulose, thaum EC sawv cev rau ethyl cellulose. Hauv tsab xov xwm no, peb yuav tham txog qhov sib txawv ntawm HEC thiab EC ntawm lawv cov qauv tshuaj, khoom siv, thiab kev nyab xeeb.

1. Chemical Structure

HEC thiab EC muaj cov qauv tshuaj sib txawv uas muab cov khoom sib txawv. HEC yog cov dej-soluble polymer uas tau los ntawm cellulose. Nws yog ib qho kev hloov kho cellulose ether uas muaj cov pab pawg hydroxyethyl txuas rau hauv cov pob txha cellulose. Qhov degree ntawm kev hloov pauv (DS) ntawm HEC yog hais txog tus naj npawb ntawm pawg hydroxyethyl uas muaj nyob rau hauv ib chav tsev anhydroglucose (AGU) ntawm cov pob txha cellulose. DS ntawm HEC tuaj yeem nyob ntawm 0.1 txog 3.0, nrog cov txiaj ntsig DS siab dua qhia tias muaj kev hloov pauv ntau dua.

EC, ntawm qhov tod tes, yog dej-insoluble polymer uas kuj tau los ntawm cellulose. Nws yog ib qho kev hloov kho cellulose ether uas muaj ethyl pawg txuas nrog cellulose qaum. DS ntawm EC yog hais txog tus naj npawb ntawm ethyl pawg uas muaj nyob rau hauv AGU ntawm cov pob txha cellulose. DS ntawm EC tuaj yeem nyob ntawm 1.7 txog 2.9, nrog rau cov txiaj ntsig DS siab dua qhia tias muaj kev hloov pauv ntau dua.

2. Cov khoom

HEC thiab EC muaj cov khoom sib txawv uas ua rau lawv haum rau kev siv sib txawv. Qee qhov tseem ceeb ntawm HEC thiab EC tau teev tseg hauv qab no:

ib. Solubility: HEC yog soluble hauv dej, thaum EC yog insoluble hauv dej. Txawm li cas los xij, EC tuaj yeem yaj hauv cov kuab tshuaj organic xws li ethanol, acetone, thiab chloroform.

b. Rheology: HEC yog cov khoom siv pseudoplastic, uas txhais tau hais tias nws nthuav tawm tus cwj pwm shear thinning. Qhov no txhais tau hais tias qhov viscosity ntawm HEC txo qis raws li tus nqi shear nce. EC, ntawm qhov tod tes, yog cov khoom siv thermoplastic, uas txhais tau hais tias nws tuaj yeem softened thiab molded thaum rhuab.

c. Zaj duab xis-forming zog: HEC muaj zoo zaj duab xis-forming zog, uas ua rau nws haum rau siv nyob rau hauv coatings thiab films. EC kuj muaj cov khoom ua yeeb yaj kiab, tab sis cov yeeb yaj kiab yuav nkig thiab ua rau tawg.

d. Stability: HEC yog ruaj khov nyob rau ntau yam ntawm pH thiab kub tej yam kev mob. EC kuj tseem ruaj khov tshaj pH dav, tab sis nws qhov kev ruaj ntseg yuav cuam tshuam los ntawm qhov kub thiab txias.

3. Siv

HEC thiab EC yog siv nyob rau hauv ntau yam kev siv hauv cov khoom noj, tshuaj, thiab kev kho tus kheej. Qee qhov kev siv tseem ceeb ntawm HEC thiab EC tau teev tseg hauv qab no:

ib. Kev lag luam zaub mov: HEC feem ntau yog siv los ua cov thickener, stabilizer, thiab emulsifier hauv cov khoom noj xws li kua ntses, hnav khaub ncaws, thiab cov khoom ci. EC yog siv los ua txheej txheej rau cov khoom noj xws li zom cov pos hniav, khoom qab zib, thiab tshuaj.

b. Kev lag luam kws tshuaj: HEC yog siv los ua ib qho kev sib khi, disintegrant, thiab ntsiav tshuaj txheej tus neeg sawv cev hauv cov tshuaj formulations. EC yog siv los ua ib qho kev sib khi, tus neeg sawv cev txheej, thiab tus neeg saib xyuas kev tso tawm nyob rau hauv cov tshuaj formulations.

4. Kev nyab xeeb

HEC thiab EC feem ntau suav hais tias muaj kev nyab xeeb rau kev siv khoom noj thiab tshuaj siv. Txawm li cas los xij, zoo li txhua yam tshuaj lom neeg, tej zaum yuav muaj qee qhov kev pheej hmoo cuam tshuam nrog lawv siv. Nws yog ib qho tseem ceeb uas yuav tsum ua raws li cov lus pom zoo rau kev siv HEC thiab EC kom ntseeg tau tias lawv muaj kev nyab xeeb thiab siv tau zoo.