Hydroxyethyl cellulose (HEC) yog ib qho tseem ceeb ntawm cov dej-soluble cellulose ether, uas yog dav siv nyob rau hauv coatings, roj drilling, tshuaj thiab lwm yam teb. Nws cov ntsiab lus melting yog ib qho tseem ceeb ntawm lub cev tsis zoo uas cuam tshuam rau nws txoj kev ua thiab kev siv. Cov yam ntxwv cuam tshuam rau lub melting point ntawm hydroxyethyl cellulose tuaj yeem muab faib ua ntau yam, xws li cov qauv molecular, qib kev hloov pauv, qhov hnyav molecular, crystallinity, impurities, thiab ib puag ncig.
1. Molecular qauv
Hydroxyethyl cellulose yog cov khoom ntawm cellulose tom qab ethoxylation. Nws lub hauv paus qauv yog tias hydrogen atoms nyob rau hauv cellulose molecule yog hloov los ntawm hydroxyethyl pawg. Txoj hauj lwm, tus lej thiab kev txiav txim ntawm hydroxyethyl hloov pauv yuav cuam tshuam rau nws cov ntsiab lus melting.
Hloov txoj haujlwm: Txhua chav piam thaj hauv cellulose muaj peb pawg hydroxyl uas tuaj yeem hloov pauv. Kev hloov pauv ntawm txoj haujlwm sib txawv yuav hloov cov qauv spatial ntawm cov molecule, yog li cuam tshuam rau lub melting point.
Tus naj npawb ntawm kev hloov pauv: Kev nce ntawm cov neeg hloov pauv feem ntau txo cov hydrogen bonding ntawm cov molecules, yog li txo qhov melting point.
Kev txiav txim ntawm kev hloov pauv: Randomly faib cov neeg hloov pauv thiab tsis tu ncua faib cov neeg hloov pauv muaj qhov sib txawv ntawm qhov hloov tau yooj yim thiab kev cuam tshuam ntawm cov saw hlau molecular, yog li cuam tshuam rau lub melting point.
2. Degree of Hloov (DS)
DS yog hais txog tus lej nruab nrab ntawm hydroxyethyl hloov pauv ntawm txhua chav tsev piam thaj. Qhov degree ntawm kev hloov pauv muaj qhov cuam tshuam tseem ceeb ntawm lub melting point, uas yog qhov tseem ceeb hauv cov hauv qab no:
Tsawg DS: Thaum qis DS, hydrogen bonding ntawm hydroxyethyl cellulose molecules muaj zog dua, ua rau cov molecules nruj nreem khi thiab qhov melting point siab dua.
High DS: High DS tsub kom qhov yooj ntawm cov molecules thiab txo cov nyhuv ntawm hydrogen bonding, ua rau cov molecules yooj yim rau swb thiab lub melting point.
3. Molecular Luj
Molecular hnyav muaj qhov cuam tshuam ncaj qha rau ntawm qhov chaw melting ntawm hydroxyethyl cellulose. Feem ntau hais lus, qhov loj dua qhov hnyav molecular, qhov ntev ntawm cov saw hlau molecular, qhov muaj zog ntawm van der Waals quab yuam ntawm cov molecules, thiab siab dua qhov melting point. Tsis tas li ntawd, qhov dav ntawm qhov hnyav molecular faib kuj tseem cuam tshuam rau qhov melting point, thiab kev faib dav yuav ua rau cov ntsiab lus tsis sib xws.
Qhov hnyav molecular: Cov saw hlau molecular ntev dua, sib txuas nrog ntau dua, thiab cov ntsiab lus melting siab.
Tsawg molecular hnyav: Cov saw hlau molecular luv dua, lub zog ntawm lub cev tsis muaj zog, thiab cov ntsiab lus melting tsawg.
4. Crystallinity
Hydroxyethyl cellulose yog amorphous polymer, tab sis nws tseem yuav muaj qee qhov chaw crystalline. Lub xub ntiag ntawm crystalline cheeb tsam ua rau kom lub melting point vim hais tias cov crystalline qauv yog ruaj khov thiab yuav tsum tau ntau zog los rhuav tshem cov qauv no. Qib ntawm hydroxyethylation thiab txheej txheem txheej txheem cuam tshuam rau nws cov crystallinity.
High crystallinity: nruj qauv, siab melting point.
Tsawg crystallinity: looser qauv, qis melting point.
5. Cov impurities
Thaum lub sij hawm tsim cov txheej txheem ntawm hydroxyethyl cellulose, qee cov khoom siv tsis zoo, cov khoom siv hluav taws xob lossis cov khoom lag luam yuav nyob twj ywm. Lub xub ntiag ntawm cov impurities tuaj yeem hloov pauv lub zog ntawm lub cev, yog li cuam tshuam rau lub melting point. Piv txwv li:
Residual catalyst: complexes yuav tsim, hloov lub melting point.
By-products: Lub xub ntiag ntawm txawv by-products yuav hloov qhov kev sib tshuam ntawm lub cev thiab cuam tshuam rau lub melting point.
6. Ib puag ncig tej yam kev mob
Ib puag ncig tej yam kev mob xws li kub thiab av noo yuav cuam tshuam qhov melting point ntawm hydroxyethyl cellulose. Nyob rau hauv high humidity tej yam kev mob, hydroxyethyl cellulose yuav undergo plasticization tom qab absorbing dej, uas yuav tsis muaj zog lub intermolecular rog thiab txo lub melting point.
Qhov kub thiab txias: Nws tuaj yeem ua rau thermal decomposition ntawm cov khoom thiab nthuav qhov melting point.
Cov av noo siab: Cov saw hlau molecular hloov tau yooj yim dua tom qab nqus dej, thiab cov ntsiab lus melting yog txo.
7. Kev Siv Tshuab
Qhov kub, shear quab yuam, ziab khaub ncaws, thiab lwm yam thaum lub sij hawm ua cov txheej txheem yuav cuam tshuam qhov melting point ntawm cov khoom kawg. Cov txheej txheem sib txawv yuav ua rau muaj kev sib txawv molecular orientations thiab crystallinity, uas nyob rau hauv lem cuam tshuam rau lub melting point.
Kev ua haujlwm kub: Kev ua haujlwm siab dua tuaj yeem ua rau qee qhov degradation lossis hla kev sib txuas, hloov pauv qhov melting point.
Qhuav tej yam kev mob: ceev kom qhuav thiab qeeb kom qhuav muaj qhov sib txawv ntawm cov txheej txheem ntawm molecules, thiab lub melting point kuj yuav txawv.
Hauv cov ntsiab lus, cov yam ntxwv uas cuam tshuam rau lub melting point ntawm hydroxyethyl cellulose muaj xws li molecular qauv, degree ntawm kev hloov, molecular hnyav, crystallinity, impurities, ib puag ncig tej yam kev mob thiab ua technology. Rau kev siv tswv yim thiab kev ua tiav, kev tswj xyuas tsim nyog ntawm cov khoom no tuaj yeem ua kom zoo dua ntawm hydroxyethyl cellulose thiab ua kom nws zoo dua raws li ntau yam kev thov. Nyob rau hauv cov txheej txheem ntau lawm, kev hloov kho ntawm cov tsis tuaj yeem tsis tsuas yog tswj lub melting point ntawm cov khoom, tab sis kuj txhim kho stability thiab zoo ntawm cov khoom.
Post lub sij hawm: Lub Xya hli ntuj-10-2024