Cellulose ether ndi polima yopangidwa ndi cellulose yachilengedwe ngati zinthu zopangira pogwiritsa ntchito mankhwala. Cellulose ether ndi yochokera ku cellulose yachilengedwe, kupanga cellulose ether ndi polima yopangidwa ndi yosiyana, zinthu zake zofunika kwambiri ndi cellulose, mankhwala achilengedwe a polymer. Chifukwa cha kapangidwe ka cellulose yachilengedwe, cellulose yokha ilibe mphamvu yochitapo kanthu ndi etherifying agent. Koma pambuyo pa chithandizo cha edema, ma hydrogen bonds amphamvu pakati pa unyolo wa mamolekyu ndi unyolo adawonongeka, ndipo ntchito ya hydroxyl group idatulutsidwa mu alkali cellulose yokhala ndi mphamvu yochitapo kanthu, ndipo cellulose ether idapezeka kudzera mu reaction ya etherifying agent — OH group into — OR group.
Kapangidwe ka ma ether a cellulose kamadalira mtundu, chiwerengero ndi kufalikira kwa ma ether. Kugawa kwa ether ya cellulose kumadaliranso mtundu wa ma ether, kuchuluka kwa ether, kusungunuka ndi kugwiritsidwa ntchito kofananako kungagawidwe m'magulu. Malinga ndi mtundu wa ma ether omwe ali pa unyolo wa mamolekyu, amatha kugawidwa m'magulu awiri: ether imodzi ndi ether yosakanikirana. MC nthawi zambiri imagwiritsidwa ntchito ngati ether imodzi, pomwe HPmc ndi ether yosakanikirana. Methyl cellulose ether MC ndi gawo lachilengedwe la shuga la cellulose pa hydroxyl ndipo methoxide yasinthidwa ndi fomula ya kapangidwe ka mankhwala [CO H7O2 (OH) 3-H (OCH3) H] X, hydroxypropyl methyl cellulose ether HPmc ndi gawo la hydroxyl lomwe lili gawo la methoxide lomwe lasinthidwa, gawo lina la chinthu chosinthidwa cha hydroxypropyl, Fomula yomangidwa ndi [C6H7O2 (OH) 3-MN (OCH3) M [OCH2CH (OH) CH3] N] X ndi hydroxyethyl methyl cellulose ether HEmc, yomwe imagwiritsidwa ntchito kwambiri ndikugulitsidwa pamsika.
Kuchokera ku kusungunuka, tingagawike m'magulu awiri: mtundu wa ionic ndi mtundu wosakhala ionic. Etha ya cellulose yosungunuka m'madzi imapangidwa makamaka ndi alkyl ether ndi hydroxyl alkyl ether. Cmc ya Ionic imagwiritsidwa ntchito kwambiri mu sopo yopangira, nsalu, kusindikiza, chakudya ndi mafuta. MC yosakhala ionic, HPmc, HEmc ndi zina zimagwiritsidwa ntchito kwambiri mu zipangizo zomangira, zokutira za latex, mankhwala, mankhwala a tsiku ndi tsiku ndi zina. Monga wothandizira wokhuthala, wothandizira wosunga madzi, wokhazikika, wothira mafuta, wothandizira wopanga filimu.
Kusunga madzi a ether ya cellulose
Pakupanga zipangizo zomangira, makamaka matope osakaniza ouma, cellulose ether imagwira ntchito yosasinthika, makamaka pakupanga matope apadera (matope osinthidwa), ndi gawo lofunika kwambiri.
Udindo wofunikira wa etha wosungunuka m'madzi mu matope uli ndi mbali zitatu, imodzi ndi luso labwino kwambiri losunga madzi, yachiwiri ndi mphamvu ya matope ogwirizana ndi thixotropy, ndipo yachitatu ndi kuyanjana ndi simenti.
Kusunga madzi a ether ya cellulose, kumadalira maziko a hydroscopicity, kapangidwe ka matope, makulidwe a matope, kufunika kwa madzi a matope, nthawi yokwanira yosunga madzi a cellulose ether. Kusunga madzi kwa ether ya cellulose kumachokera ku kusungunuka ndi kuchepa kwa madzi kwa ether ya cellulose yokha. Ndizodziwika bwino kuti ma cellulose molecular chains, ngakhale ali ndi magulu ambiri a OH omwe ali ndi madzi ambiri, sasungunuka m'madzi chifukwa cha kapangidwe kawo ka crystalline. Mphamvu ya hydration ya magulu a hydroxyl yokha sikokwanira kulipira ma hydrogen bonds amphamvu pakati pa mamolekyulu ndi mphamvu za van der Waals. Pamene ma substituents alowetsedwa mu unyolo wa mamolekyulu, si ma substituents okha omwe amawononga unyolo wa hydrogen, komanso ma interchain hydrogen bonds amasweka chifukwa cha kugawanika kwa ma substituents pakati pa ma chain oyandikana nawo. Ma substituents akakula, mtunda pakati pa mamolekyu umakhala waukulu. Pamene hydrogen bond effect ikuwonongeka kwambiri, cellulose lattice expansion, yankho limalowa mu cellulose ether limakhala losungunuka m'madzi, kupanga high viscosity solution. Pamene kutentha kukukwera, madzi a polima amachepa ndipo madzi pakati pa maunyolo amatuluka. Pamene mphamvu yochotsa madzi m'thupi imakhala yokwanira, mamolekyu amayamba kusonkhana ndipo gel imapindika mu netiweki ya magawo atatu. Zinthu zomwe zimakhudza kusunga madzi mu matope ndi monga kukhuthala kwa cellulose ether, mlingo, kupyapyala kwa tinthu tating'onoting'ono ndi kutentha kwa ntchito.
Kukhuthala kwa etha ya cellulose kukakhala kwakukulu, kukhuthala kwa madzi kumakhala bwino, komanso kukhuthala kwa yankho la polima kumakhala bwino. Kulemera kwa molekyulu (mlingo wa polymerization) ya polima kumatsimikiziridwanso ndi kutalika ndi mawonekedwe a kapangidwe ka molekyulu ya unyolo, ndipo kufalikira kwa chiwerengero cha zinthu zina kumakhudza mwachindunji kuchuluka kwa kukhuthala. [eta] = Km alpha
Kukhuthala kwamkati kwa mayankho a polima
Kulemera kwa molekyulu ya polima ya M
α polima khalidwe chosasintha
K viscosity solution coefficient
Kukhuthala kwa yankho la polima kumadalira kulemera kwa mamolekyulu a polima. Kukhuthala ndi kuchuluka kwa mayankho a ether a cellulose zimagwirizana ndi ntchito zosiyanasiyana. Chifukwa chake, ether iliyonse ya cellulose ili ndi mafotokozedwe osiyanasiyana a kukhuthala, malamulo a kukhuthala amapangidwanso makamaka kudzera mu kuwonongeka kwa cellulose ya alkali, yomwe ndi kusweka kwa unyolo wa maselo a cellulose kuti akwaniritse.
Pa kukula kwa tinthu, tinthu tating'onoting'ono tikakhala tating'onoting'ono, madzi amasungidwa bwino. Tinthu tating'onoting'ono ta cellulose ether tikakumana ndi madzi, pamwamba pake timasungunuka nthawi yomweyo ndikupanga gel yokulunga zinthuzo kuti mamolekyu amadzi asapitirire kulowa, nthawi zina kusakaniza kwa nthawi yayitali sikungasakanizidwe mofanana, kupangika kwa yankho la matope lodzaza ndi flocculent kapena agglomerate. Kusungunuka kwa cellulose ether ndi chimodzi mwazinthu zomwe zimasankha cellulose ether.
Kukhuthala ndi thixotropy ya efa ya cellulose
Zotsatira zachiwiri za ether ya cellulose - kukhuthala kumadalira: digiri ya polymerization ya ether ya cellulose, kuchuluka kwa yankho, kuchuluka kwa shear, kutentha ndi zina. Kapangidwe ka gelation ka yankho ndi kapadera kwa alkyl cellulose ndi zotumphukira zake zosinthidwa. Makhalidwe a gelation amagwirizana ndi kuchuluka kwa kusintha, kuchuluka kwa yankho ndi zowonjezera. Pa zotumphukira zosinthidwa za hydroxyl alkyl, mawonekedwe a gel amagwirizananso ndi kuchuluka kwa hydroxyl alkyl modified. Pa kuchuluka kwa yankho la MC ndi HPmc, kuchuluka kwa 10%-15% kungakonzedwe, kuchuluka kwa medium viscosity MC ndi HPmc kungakonzedwe yankho la 5%-10% ndi kuchuluka kwa viscosity MC ndi HPmc kungakonzedwe yankho la 2%-3%, ndipo nthawi zambiri kukhuthala kwa ether ya cellulose kumayesedwanso ndi yankho la 1%-2%. Kuchuluka kwa mamolekyulu a cellulose ether thickener, kuchuluka komweko kwa yankho, ma polima osiyanasiyana a molekyulu ali ndi kukhuthala kosiyana, kukhuthala ndi kulemera kwa mamolekyulu zitha kufotokozedwa motere, [η]=2.92×10-2 (DPn) 0.905, DPn ndi digiri yapakati ya polymerization yapamwamba. Kuchuluka kwa mamolekyulu a cellulose ether kuti muwonjezere zambiri kuti mukwaniritse kukhuthala komwe mukufuna. Kukhuthala kwake sikudalira kwambiri kuchuluka kwa shear, kukhuthala kwakukulu kuti mukwaniritse kukhuthala komwe mukufuna, kuchuluka komwe kumafunika kuti muwonjezere pang'ono, kukhuthala kumadalira kukhuthala komwe kukufunika. Chifukwa chake, kuti mukwaniritse kusinthasintha kwina, kuchuluka kwa cellulose ether (kuchuluka kwa yankho) ndi kukhuthala kwa yankho kuyenera kutsimikizika. Kutentha kwa gelation kwa yankho kunachepa motsatizana ndi kuwonjezeka kwa kuchuluka kwa yankho, ndipo gelation inachitika kutentha kwa chipinda mutafika pa kuchuluka kwina. HPmc ili ndi kuchuluka kwa gelation kwakukulu kutentha kwa chipinda.
Kusinthasintha kungasinthidwenso posankha kukula kwa tinthu tating'onoting'ono ndi ma ether a cellulose okhala ndi madigiri osiyanasiyana osinthira. Chomwe chimatchedwa kusintha ndi kuyambitsa gulu la hydroxyl alkyl mumlingo winawake wosinthira kapangidwe ka mafupa a MC. Mwa kusintha ma value osinthira ofanana a ma substituent awiri, ndiko kuti, ma value osinthira ofanana a DS ndi MS a magulu a methoxy ndi hydroxyl. Makhalidwe osiyanasiyana a ether ya cellulose amafunikira posintha ma value osinthira ofanana a mitundu iwiri ya ma substituent.
ubale pakati pa kusinthasintha ndi kusintha. Mu Chithunzi 5, kuwonjezera kwa cellulose ether kumakhudza momwe madzi amagwiritsidwira ntchito mu matope ndikusintha chiŵerengero cha madzi ndi simenti, chomwe ndi mphamvu yokhuthala. Mlingo ukakhala wokwera, madzi amagwiritsidwira ntchito kwambiri.
Ma cellulose ether omwe amagwiritsidwa ntchito mu zipangizo zomangira za ufa ayenera kusungunuka mwachangu m'madzi ozizira ndikupatsa makinawo kusinthasintha koyenera. Ngati chiŵerengero cha kudulidwa kwa chinthucho chikadali chofooka komanso chopanda mphamvu, ndiye kuti ndi chinthu chosakwanira kapena chapamwamba.
Palinso ubale wabwino pakati pa kugwirizana kwa simenti ndi kuchuluka kwa etha ya cellulose, etha ya cellulose imatha kukulitsa kwambiri kukhuthala kwa matope, kuchuluka kwa mlingo, ndi momwe zotsatira zake zimaonekera.
Madzi a Cellulose ether okhala ndi kukhuthala kwakukulu ali ndi thixotropy yapamwamba, yomwe ndi imodzi mwa makhalidwe a cellulose ether. Madzi a ma polima a mtundu wa Mc nthawi zambiri amakhala ndi pseudoplastic, non-thixotropic fluidity pansi pa kutentha kwa gel, koma Newtonian flow properties pamlingo wotsika wa shear. Pseudoplasticity imawonjezeka ndi kuwonjezeka kwa kulemera kwa molekyulu kapena kuchuluka kwa cellulose ether ndipo sikudalira mtundu ndi digiri yosinthira. Chifukwa chake, cellulose ethers a kalasi yofanana ya kukhuthala, kaya MC, HPmc kapena HEmc, nthawi zonse amawonetsa makhalidwe ofanana a rheological bola ngati kuchuluka ndi kutentha kumakhalabe kosasintha. Kutentha kukakwera, structural gel imapangidwa ndipo kuyenda kwa thixotropic kwakukulu kumachitika. Cellulose ethers okhala ndi kukhuthala kwakukulu komanso kukhuthala kochepa amasonyeza thixotropy ngakhale pansi pa kutentha kwa gel. Katunduyu ndi wothandiza kwambiri pakupanga matope omangira kuti asinthe kayendedwe kake ndi kukhuthala kwake. Apa pakufunika kufotokoza kuti kukhuthala kwa etha ya cellulose kumakhala kwakukulu, kusunga madzi kumakhala bwino, koma kukhuthala kumakhala kwakukulu, kulemera kwa maselo a etha ya cellulose kumakhala kwakukulu, kuchepetsa kusungunuka kwake, komwe kumakhudza kwambiri kuchuluka kwa matope ndi magwiridwe antchito omanga. Kukhuthala kumakhala kwakukulu, kukhuthala kwa matope kumaonekera bwino, koma si ubale wokwanira. Kukhuthala kochepa, koma kosinthidwa kwa etha ya cellulose pokonza mphamvu ya matope onyowa kumakhala ndi magwiridwe antchito abwino kwambiri, ndi kuwonjezeka kwa kukhuthala, kusunga madzi a etha ya cellulose kumawonjezeka.
Nthawi yotumizira: Marichi-30-2022