Kusintha kwa etherification ya cellulose

01. Kuyambitsa kwa selulose

Cellulose ndi polysaccharide yayikulu yopangidwa ndi shuga. Sisungunuka m'madzi ndi zinthu zina zachilengedwe. Ndi gawo lalikulu la khoma la maselo a zomera, komanso ndi polysaccharide yofalikira kwambiri komanso yochuluka kwambiri m'chilengedwe.

Cellulose ndiye chuma chobwezerezedwanso chochuluka kwambiri padziko lonse lapansi, komanso ndi polima yachilengedwe yokhala ndi kuchuluka kwakukulu. Ili ndi ubwino wokhala ndi mphamvu zobwezerezedwanso, wokhoza kuwola kwathunthu, komanso wogwirizana bwino ndi zinthu zina.

02. Zifukwa zosinthira cellulose

Ma cellulose macromolecules ali ndi magulu ambiri a -OH. Chifukwa cha mphamvu ya ma hydrogen bonds, mphamvu pakati pa ma macromolecules ndi yayikulu, zomwe zimapangitsa kuti enthalpy melting entilpy △H isungunuke kwambiri; kumbali ina, pali mphete mu ma cellulose macromolecules. Monga kapangidwe kake, kuuma kwa unyolo wa mamolekyulu kumakhala kwakukulu, zomwe zimapangitsa kuti entropy melting entropy isinthe pang'ono ΔS. Zifukwa ziwirizi zimapangitsa kuti kutentha kwa cellulose yosungunuka (= △H / △S ) kukhale kwakukulu, ndipo kutentha kwa cellulose kumakhala kotsika. Chifukwa chake, cellulose ikatenthedwa kutentha kwina, ulusi umaonekera. Chodabwitsa n'chakuti cellulose yawonongeka isanayambe kusungunuka, chifukwa chake, kukonza zinthu za cellulose sikungatenge njira yoyamba kusungunuka kenako kupanga.

03. Kufunika kwa kusintha kwa cellulose

Chifukwa cha kuchepa pang'onopang'ono kwa zinthu zakale komanso mavuto aakulu azachilengedwe omwe amabwera chifukwa cha nsalu za ulusi wa mankhwala otayira zinyalala, kupanga ndi kugwiritsa ntchito ulusi wachilengedwe wongowonjezedwanso kwakhala chimodzi mwa zinthu zomwe anthu amasamala kwambiri. Cellulose ndiye chuma chachilengedwe chongowonjezedwanso chomwe chilipo kwambiri m'chilengedwe. Ili ndi zinthu zabwino kwambiri monga hygroscopicity yabwino, antistatic, mpweya wamphamvu wolowa, utoto wabwino, kuvala bwino, kukonza nsalu mosavuta, komanso kuwonongeka kwa zinthu. Ili ndi makhalidwe omwe sangafanane ndi ulusi wa mankhwala.

Mamolekyulu a cellulose ali ndi magulu ambiri a hydroxyl, omwe ndi osavuta kupanga ma hydrogen bond amkati mwa mamolekyulu ndi pakati pa mamolekyulu, ndipo amawola kutentha kwambiri popanda kusungunuka. Komabe, cellulose ili ndi reactivity yabwino, ndipo hydrogen bond yake imatha kuwonongedwa ndi kusintha kwa mankhwala kapena grafting reaction, zomwe zingathandize kuchepetsa kusungunuka. Monga zinthu zosiyanasiyana zamafakitale, imagwiritsidwa ntchito kwambiri mu nsalu, kulekanitsa nembanemba, mapulasitiki, fodya ndi zokutira.

04. Kusintha kwa etherification ya cellulose

Cellulose ether ndi mtundu wa cellulose derivative womwe umapezeka posintha etherification ya cellulose. Umagwiritsidwa ntchito kwambiri chifukwa cha kukhuthala kwake kwabwino, emulsification, suspension, film formation, protective colloid, chinyezi, komanso mphamvu zomatira. Umagwiritsidwa ntchito muzakudya, mankhwala, kupanga mapepala, utoto, zipangizo zomangira, ndi zina zotero.

Kuphatikizika kwa cellulose ndi mndandanda wa zinthu zomwe zimapangidwa ndi momwe magulu a hydroxyl amachitira pa unyolo wa maselo a cellulose ndi zinthu zotchedwa alkylating agents pansi pa mikhalidwe ya alkaline. Kugwiritsa ntchito magulu a hydroxyl kumachepetsa kuchuluka kwa ma hydrogen bond pakati pa mamolekyulu kuti achepetse mphamvu za mamolekyulu, motero kumawonjezera kukhazikika kwa kutentha kwa cellulose, kukonza magwiridwe antchito a zinthu, komanso nthawi yomweyo kuchepetsa kutentha kwa cellulose.

Zitsanzo za zotsatira za kusintha kwa etherification pa ntchito zina za cellulose:

Pogwiritsa ntchito thonje loyengedwa ngati zinthu zoyambira, ofufuzawo adagwiritsa ntchito njira imodzi yopangira ether kuti akonze ether ya carboxymethyl hydroxypropyl cellulose yokhala ndi reaction yofanana, kukhuthala kwakukulu, kukana asidi bwino komanso kukana mchere kudzera mu alkalization ndi etherification reactions. Pogwiritsa ntchito njira imodzi yopangira ether, carboxymethyl hydroxypropyl cellulose yopangidwa imakhala ndi kukana mchere bwino, kukana asidi komanso kusungunuka. Mwa kusintha kuchuluka kwa propylene oxide ndi chloroacetic acid, zinthu zomwe zili ndi carboxymethyl ndi hydroxypropyl zosiyanasiyana zitha kukonzedwa. Zotsatira za mayeso zikuwonetsa kuti carboxymethyl hydroxypropyl cellulose yopangidwa ndi njira imodzi imakhala ndi nthawi yochepa yopangira, kugwiritsa ntchito solvent kochepa, ndipo mankhwalawa ali ndi kukana bwino mchere wa monovalent ndi divalent komanso kukana asidi bwino.

05. Chiyembekezo cha kusintha kwa etherification ya cellulose

Cellulose ndi chinthu chofunikira kwambiri cha mankhwala ndi mankhwala chomwe chili ndi zinthu zambiri, chobiriwira komanso choteteza chilengedwe, komanso chobwezerezedwanso. Zochokera mu kusintha kwa etherification ya cellulose zimakhala ndi magwiridwe antchito abwino kwambiri, zimasiyana kwambiri pakugwiritsa ntchito komanso zimakwaniritsa bwino kwambiri zosowa za chuma cha dziko. Ndipo zosowa za chitukuko cha anthu, ndi kupita patsogolo kwaukadaulo kosalekeza komanso kukwaniritsa malonda mtsogolo, ngati zinthu zopangira ndi njira zopangira za cellulose zitha kupangidwa kukhala mafakitale ambiri, zidzagwiritsidwa ntchito mokwanira ndikugwiritsa ntchito mitundu yosiyanasiyana ya ntchito.