Cellulose ether wani nau'in polymer ne da aka yi da cellulose na halitta a matsayin kayan da aka ƙera ta hanyar gyaran sinadarai. Cellulose ether wani abu ne da aka samo daga cellulose na halitta, samar da cellulose ether da kuma polymer na roba ya bambanta, mafi mahimmancin kayansa shine cellulose, mahaɗan polymer na halitta. Saboda takamaiman tsarin cellulose na halitta, cellulose kanta ba ta da ikon yin aiki tare da wakilin etherifying. Amma bayan maganin maganin kumburi, an lalata haɗin hydrogen mai ƙarfi tsakanin sarƙoƙi da sarƙoƙi, kuma an saki aikin rukunin hydroxyl cikin cellulose na alkali tare da ikon amsawa, kuma an sami cellulose ether ta hanyar amsawar wakilin etherifying - ƙungiyar OH zuwa cikin ƙungiyar OR.
Halayen ethers na cellulose sun dogara ne akan nau'in, adadi da rarrabawar abubuwan maye. Rarraba ether na cellulose kuma ya dogara ne akan nau'in abubuwan maye, ana iya rarraba matakin etherification, narkewa da aikace-aikacen da suka shafi hakan. Dangane da nau'in abubuwan maye akan sarkar kwayoyin halitta, ana iya raba shi zuwa ether ɗaya da ether gauraye. Yawanci ana amfani da MC azaman ether ɗaya, yayin da HPmc shine ether gauraye. Methyl cellulose ether MC wani sinadari ne na halitta na glucose cellulose akan hydroxyl wanda aka maye gurbinsa da tsarin samfurin [CO H7O2 (OH) 3-H (OCH3) H] X, hydroxypropyl methyl cellulose ether HPmc wani sinadari ne akan hydroxyl wani ɓangare ne na methoxide da aka maye gurbinsa, wani ɓangare na samfurin da aka maye gurbinsa da hydroxypropyl, Tsarin sinadari shine [C6H7O2 (OH) 3-MN (OCH3) M [OCH2CH (OH) CH3] N] X da hydroxyethyl methyl cellulose ether HEmc, wanda ake amfani da shi sosai kuma ana sayarwa a kasuwa.
Daga narkewar za a iya raba shi zuwa nau'in ionic da nau'in da ba ionic ba. Cellulose ether mai narkewar ruwa wanda ba ionic ba galibi ya ƙunshi nau'ikan alkyl ether da hydroxyl alkyl ether guda biyu. Ana amfani da Ionic Cmc galibi a cikin sabulun sabulu na roba, yadi, bugu, abinci da amfani da mai. Non-ionic MC, HPmc, HEmc da sauran galibi ana amfani da su a cikin kayan gini, murfin latex, magani, sunadarai na yau da kullun da sauran fannoni. A matsayin mai kauri, wakilin riƙe ruwa, mai daidaita, mai watsawa, wakilin samar da fim.
Rikewar ruwa ta Cellulose ether
A fannin samar da kayan gini, musamman busasshen turmi gauraye, cellulose ether yana taka muhimmiyar rawa, musamman wajen samar da turmi na musamman (turmi da aka gyara), muhimmin bangare ne na hakan.
Muhimmin rawar da cellulose ether mai narkewa cikin ruwa ke takawa a cikin turmi galibi yana da fannoni uku, ɗaya shine kyakkyawan ikon riƙe ruwa, na biyu shine tasirin daidaiton turmi da thixotropy, na uku kuma shine hulɗa da siminti.
Rikewar ruwa ta cellulose ether, ya dogara ne akan tushen hydroscopicity, abun da ke cikin turmi, kauri na layin turmi, buƙatar ruwan turmi, lokacin da ake daskare kayan condensation. Rikewar ruwa ta cellulose ether ta fito ne daga narkewar ruwa da bushewar cellulose ether da kanta. Sanannen abu ne cewa sarƙoƙin ƙwayoyin cellulose, kodayake suna ɗauke da adadi mai yawa na ƙungiyoyin OH masu ruwa sosai, ba sa narkewa a cikin ruwa saboda tsarin kristal ɗinsu mai ƙarfi. Ikon ruwa na ƙungiyoyin hydroxyl kaɗai bai isa ya biya ƙarfin haɗin hydrogen na intermolecular da ƙarfin van der Waals ba. Lokacin da aka shigar da maye a cikin sarƙar ƙwayoyin halitta, ba wai kawai maye gurbin suna lalata sarƙar hydrogen ba, har ma haɗin hydrogen na interchain yana karyewa saboda haɗa maye tsakanin sarƙoƙi maƙwabta. Girman maye gurbin yana da yawa, mafi girman nisa tsakanin ƙwayoyin halitta. Mafi girman lalata tasirin haɗin hydrogen, faɗaɗa layin cellulose, mafita a cikin cellulose ether ya zama mai narkewa cikin ruwa, samuwar babban maganin danko. Yayin da zafin jiki ke ƙaruwa, ruwan polymer ɗin yana raguwa kuma ruwan da ke tsakanin sarƙoƙi zai ƙare. Idan tasirin bushewar ya isa, ƙwayoyin suna fara taruwa kuma gel ɗin yana naɗewa a cikin hanyar sadarwa mai girma uku. Abubuwan da ke shafar riƙe ruwa na turmi sun haɗa da ɗanɗanon cellulose ether, yawan amfani, ƙanƙantar barbashi da zafin sabis.
Girman danko na cellulose ether, mafi kyawun aikin riƙe ruwa, da kuma danko na ruwan polymer. Nauyin kwayoyin halitta (matakin polymerization) na polymer kuma ana tantance shi ta hanyar tsayi da yanayin tsarin kwayoyin halitta na sarkar, kuma rarrabawar adadin abubuwan maye yana shafar kewayon danko kai tsaye. [eta] = Km alpha
Danko na ciki na mafita na polymer
Nauyin ƙwayoyin polymer M
α yanayin polymer
Ma'aunin maganin danko na K
Dankowar ruwan polymer ya dogara ne akan nauyin kwayoyin polymer. Dankowar ruwan cellulose da yawan ruwan cellulose ether suna da alaƙa da aikace-aikace daban-daban. Saboda haka, kowace cellulose ether tana da ƙayyadaddun danko daban-daban, kuma tsarin danko shine galibi ta hanyar lalata cellulose na alkali, wato karyewar sarkar kwayoyin cellulose don cimmawa.
Don girman ƙwayoyin cuta, gwargwadon yadda ƙwayoyin cuta ke da kyau, haka nan ma riƙe ruwa zai fi kyau. Manyan ƙwayoyin cuta na cellulose ether suna hulɗa da ruwa, saman yana narkewa nan take kuma yana samar da gel don naɗe kayan don hana ƙwayoyin ruwa ci gaba da shiga, wani lokacin juyawa na dogon lokaci ba za a iya wargaza su daidai ba, samuwar maganin flocculent mai laka ko agglomerate. Narkewar cellulose ether yana ɗaya daga cikin abubuwan da ake zaɓar cellulose ether.
Kauri da kuma thixotropy na cellulose ether
Tasiri na biyu na cellulose ether - kauri ya dogara da: matakin polymerization na cellulose ether, yawan ruwan da ke cikinsa, saurin yankewa, zafin jiki da sauran yanayi. Siffar gelation na maganin ya kebanta da cellulose na alkyl da abubuwan da aka gyara. Sifofin gelation suna da alaƙa da matakin maye gurbinsa, yawan ruwan da aka haɗa da ƙari. Ga abubuwan da aka gyara na hydroxyl alkyl, halayen gel suma suna da alaƙa da matakin hydroxyl alkyl gyaggyara. Don yawan ruwan da ke cikin MC da HPmc, ana iya shirya maganin 10%-15% gyaggyara, matsakaicin ruwan da ke cikin MC da HPmc za a iya shirya maganin 5%-10% kuma babban ruwan da ke cikin MC da HPmc za a iya shirya maganin 2%-3% kawai, kuma yawanci ana auna danko na cellulose ether da kashi 1%-2%. Ingancin sinadarin cellulose ether mai nauyin ƙwayoyin halitta mai yawa, yawan sinadarin da aka haɗa, nau'ikan polymers daban-daban suna da bambancin danko, ana iya bayyana danko da nauyin ƙwayoyin halitta kamar haka, [η]=2.92×10-2 (DPn) 0.905, DPn shine matsakaicin matakin polymerization na babban. Ƙaramin cellulose ether mai nauyin ƙwayoyin halitta don ƙara ƙari don cimma danko da aka haɗa. Dankonsa ba ya dogara da ƙimar yankewa, babban danko don cimma danko da aka haɗa, adadin da ake buƙata don ƙarawa ƙasa, danko ya dogara da ingancin kauri. Saboda haka, don cimma daidaito, dole ne a tabbatar da wani adadin cellulose ether (tattarawar maganin) da danko da aka haɗa. Zafin gelation na maganin ya ragu a layi tare da ƙaruwar yawan sinadarin, kuma gelation ya faru a zafin ɗaki bayan ya kai wani takamaiman adadin. HPmc yana da babban yawan gelation a zafin ɗaki.
Haka kuma ana iya daidaita daidaiton ta hanyar zaɓar girman barbashi da kuma cellulose ethers tare da matakai daban-daban na gyara. Abin da ake kira gyare-gyare shine gabatar da ƙungiyar hydroxyl alkyl a cikin wani mataki na maye gurbin akan tsarin kwarangwal na MC. Ta hanyar canza ƙimar maye gurbin dangi na maye gurbin biyu, wato, ƙimar maye gurbin dangi na DS da MS na ƙungiyoyin methoxy da hydroxyl. Ana buƙatar halaye daban-daban na cellulose ether ta hanyar canza ƙimar maye gurbin dangi na nau'ikan maye biyu.
alaƙar da ke tsakanin daidaito da gyare-gyare. A cikin Hoto na 5, ƙara cellulose ether yana shafar yawan ruwan turmi kuma yana canza rabon ruwa-daura na ruwa da siminti, wanda shine tasirin kauri. Girman adadin, haka nan yawan shan ruwa.
Dole ne ƙwayoyin cellulose da ake amfani da su a cikin kayan gini masu ƙura su narke da sauri a cikin ruwan sanyi kuma su samar da tsarin da ya dace. Idan ƙimar yankewa har yanzu tana da ƙarfi da kuma colloidal, samfurin ba shi da inganci ko kuma mara inganci.
Akwai kuma kyakkyawar alaƙa tsakanin daidaiton siminti da kuma yawan sinadarin cellulose ether, cellulose ether na iya ƙara yawan turmi, yayin da yawan sinadarin ke ƙaruwa, tasirinsa ke ƙaruwa.
Maganin ruwa na cellulose ether mai yawan danko yana da yawan thixotropy, wanda shine daya daga cikin halayen cellulose ether. Maganin ruwa na polymers na nau'in Mc yawanci suna da pseudoplastic, wanda ba thixotropic ba ne a ƙasa da zafin gel ɗinsu, amma halayen kwararar Newtonian a ƙarancin ƙimar yankewa. Pseudoplasticity yana ƙaruwa tare da ƙaruwar nauyin kwayoyin halitta ko yawan cellulose ether kuma yana da alaƙa da nau'in maye gurbin da digiri. Saboda haka, cellulose ethers na matakin danko iri ɗaya, ko MC, HPmc ko HEmc, koyaushe suna nuna irin wannan halayen rheological matuƙar yawan da zafin jiki ya kasance iri ɗaya. Lokacin da zafin jiki ya ƙaru, ana samar da gel na tsari kuma babban kwararar thixotropic yana faruwa. Cellulose ethers masu yawan maida hankali da ƙarancin danko suna nuna thixotropy ko da ƙasa da zafin gel. Wannan kadarar tana da babban fa'ida ga gina turmi na gini don daidaita yanayin kwarara da kwararar da ke rataye. Ya kamata a yi bayani a nan cewa yawan danko na cellulose ether, mafi kyawun riƙe ruwa, amma mafi girman danko, mafi girman nauyin kwayoyin halitta na cellulose ether, da kuma raguwar narkewarsa, wanda ke da mummunan tasiri ga yawan turmi da aikin gini. Mafi girman danko, mafi girman tasirin kauri na turmi, amma ba cikakkiyar alaƙa ce ta daidaito ba. Wasu ƙananan danko, amma an gyara cellulose ether wajen inganta ƙarfin tsarin turmi mai danshi, suna da kyakkyawan aiki, tare da ƙaruwar danko, an inganta riƙe ruwa na cellulose ether.
Lokacin Saƙo: Maris-30-2022