Focus on Cellulose ethers

Izakhiwo ze-sodium carboxymethyl cellulose kanye nesingeniso somkhiqizo

I-sodium carboxymethyl cellulose, ebizwa ngokuthi i-carboxymethyl cellulose (CMC) iwuhlobo lwe-fiber ether ephezulu ye-polymer elungiswe ukuguqulwa kwamakhemikhali kwe-cellulose yemvelo. Ukwakheka kwayo ngokuyinhloko iyunithi ye-D-glucose ngo-β (1→4) Okhiye baxhunywe ndawonye.

I-CMC iyimpushana emhlophe noma eyi-milky emhlophe noma ama-granules, anobuningi obungu-0.5-0.7 g/cm3, cishe ayinaphunga, ayinambitheki, futhi i-hygroscopic. Ihlakazeka kalula emanzini ukuze yenze isixazululo se-colloidal esobala, esingancibiliki kumakhemikhali ezinto eziphilayo njenge-ethanol. I-pH ye-aqueous solution engu-1% ingu-6.5-8.5, lapho i-pH>10 noma <5, i-viscosity ye-mucilage iyancipha kakhulu, futhi ukusebenza kuba kuhle kakhulu uma i-pH=7. Izinzile ekushiseni, i-viscosity ikhuphuka ngokushesha ngaphansi kuka-20°C, futhi ishintsha kancane ku-45°C. Ukushisa isikhathi eside ngaphezu kuka-80°C kungashintsha i-colloid futhi kunciphise ngokuphawulekayo i-viscosity nokusebenza. Incibilika kalula emanzini futhi isisombululo sisobala; izinzile kakhulu kusisombululo se-alkaline, kodwa i-hydrolyzed kalula uma ihlangana ne-asidi, futhi izokwehla lapho inani le-pH liyi-2-3, futhi izophinde isabele ngosawoti wensimbi we-multivalent.

Ifomula yesakhiwo: C6H7(OH)2OCH2COONA Ifomula yemolekyuli: C8H11O5Na

Ukusabela okuyinhloko ukuthi: i-cellulose yemvelo kuqala ithola ukusabela kwe-alkalinization nge-NaOH, futhi ngokungezwa kwe-chloroacetic acid, i-hydrogen eqenjini le-hydroxyl kuyunithi ye-glucose ibhekana nokusabela esikhundleni seqembu le-carboxymethyl ku-chloroacetic acid. Kungabonakala kufomula yesakhiwo ukuthi kunamaqembu amathathu e-hydroxyl kuyunithi ngayinye ye-glucose, okungukuthi, amaqembu e-C2, C3, kanye ne-C6 hydroxyl. I-hydrogen eqenjini ngalinye le-hydroxyl ithathelwa indawo yi-carboxymethyl, echazwa njenge-degree of substitution of 3. Izinga lokushintshwa kwe-CMC lithinta ngokuqondile ukuncibilika, ukuxubha, ukuqina, ukuzinza, ukumelana ne-asidi kanye nokumelana nosawotiI-CMC .

Ngokuvamile kunenkolelo yokuthi uma izinga lokushintsha liseduze kuka-0.6-0.7, ukusebenza kwe-emulsifying kuba ngcono, futhi ngokwanda kwezinga lokushintshwa, ezinye izakhiwo ziyathuthukiswa ngokufanele. Lapho izinga lokushintsha lingaphezu kuka-0.8, ukumelana kwayo ne-asidi nokumelana nosawoti kuyathuthukiswa kakhulu. .

Ukwengeza, kuphinde kushiwo ngenhla ukuthi kunamaqembu amathathu e-hydroxyl kuyunithi ngayinye, okungukuthi, amaqembu e-hydroxyl yesibili ye-C2 ne-C3 kanye neqembu le-hydroxyl eliyinhloko le-C6. Ngokombono, umsebenzi weqembu eliyinhloko le-hydroxyl mkhulu kunoweqembu lesibili le-hydroxyl, kodwa ngokusho komphumela we-isotopic we-C, iqembu le--OH ku-C2 I-acidic eyengeziwe, ikakhulukazi endaweni ye-alkali enamandla, umsebenzi wayo. inamandla kune-C3 ne-C6, ngakho-ke ijwayele ukusabela esikhundleni, ilandelwe yi-C6, futhi i-C3 ibuthakathaka kakhulu.

Eqinisweni, ukusebenza kwe-CMC akuhlobene kuphela nezinga lokushintsha, kodwa futhi nokufana kokusatshalaliswa kwamaqembu e-carboxymethyl kuyo yonke i-molecule ye-cellulose kanye nokushintshwa kwamaqembu e-hydroxymethyl kuyunithi ngayinye nge-C2, C3, ne-C6 i-molecule ngayinye. okuhlobene nokufana. Njengoba i-CMC iyinhlanganisela yomugqa eyenziwe nge-polymerized kakhulu, futhi iqembu layo le-carboxymethyl linokushintshwa okulinganayo ku-molecule, ama-molecule anomumo ohlukile lapho ikhambi lishiywe limile, nobude be-molecule yomugqa buhlukile uma kukhona amandla okugunda esixazululweni. . I-axis inomkhuba wokuphendukela ekuqondeni kokugeleza, futhi lokhu kuthambekela kuba namandla ngokunyuka kwezinga lokugunda kuze kube yilapho ukuqondiswa kokugcina kuhlelwe ngokuphelele. Lesi sici se-CMC sibizwa nge-pseudoplasticity. I-pseudoplasticity ye-CMC ihambisana ne-homogenization kanye nokuthuthwa kwamapayipi, futhi ngeke inambithe i-greasy obisini oluwuketshezi, okusiza ekukhishweni kwephunga lobisi. .

Ukuze sisebenzise imikhiqizo ye-CMC, sidinga ukuqonda kahle imingcele eyinhloko njengokuzinza, i-viscosity, ukumelana ne-asidi, kanye ne-viscosity. Yazi ukuthi sikhetha kanjani umkhiqizo olungile.

Imikhiqizo ye-CMC ene-viscosity ephansi inokunambitheka okuqabulayo, i-viscosity ephansi, futhi cishe ayinawo umuzwa owugqinsi. Zisetshenziswa kakhulu kumasoso akhethekile neziphuzo. Uketshezi oluphuzwayo lwezempilo nakho kuyisinqumo esihle.

Imikhiqizo ye-Medium-viscosity ye-CMC isetshenziswa kakhulu eziphuzweni eziqinile, eziphuzweni ezijwayelekile zamaprotheni kanye nejusi yezithelo. Indlela yokukhetha incike emikhubeni yomuntu siqu yonjiniyela. Ekuzinzeni kweziphuzo zobisi, i-CMC ifake isandla kakhulu.

Imikhiqizo ye-CMC ene-viscosity ephezulu inendawo enkulu yokufaka isicelo. Uma kuqhathaniswa nesitashi, i-guar gum, i-xanthan gum neminye imikhiqizo, ukuzinza kwe-CMC kusesobala, ikakhulukazi emikhiqizweni yenyama, inzuzo yokugcina amanzi ye-CMC isobala kakhulu! Phakathi kokuqiniswa okufana no-ayisikhilimu, i-CMC nayo iyisinqumo esihle.

Izinkomba eziyinhloko zokukala ikhwalithi ye-CMC yi-degree of substitution (DS) nobumsulwa. Ngokuvamile, izakhiwo ze-CMC zihlukile uma i-DS ihlukile; izinga lokushintsha liphakeme, kuqina ukuncibilika, kanye nokuba sobala nokuzinza kwesixazululo. Ngokwemibiko, ukucaca kwe-CMC kungcono uma izinga lokushintshwa liyi-0.7-1.2, futhi i-viscosity yesisombululo sayo esinamanzi inkulu kakhulu lapho inani le-pH liyi-6-9.

Ukuze kuqinisekiswe ikhwalithi yayo, ngaphezu kokukhethwa komenzeli wokufaka i-etherification, ezinye izici ezithinta izinga lokushintsha nobumsulwa nazo kufanele zicatshangelwe, njengobudlelwane phakathi kwenani le-alkali ne-etherification ejenti, isikhathi sokufaka i-etherification, okuqukethwe kwamanzi uhlelo, izinga lokushisa, inani le-DH, isixazululo Ukugxila nosawoti njll.

isingeniso somkhiqizo

Izinga lemikhiqizo eqediwe ye-CMC ikakhulukazi lincike kwisixazululo somkhiqizo. Uma isixazululo somkhiqizo sicacile, kunezinhlayiya ezimbalwa zejeli, imicu yamahhala, namabala amnyama okungcola, kuqinisekiswa ngokuyisisekelo ukuthi izinga le-CMC lihle. Uma isisombululo sishiywe izinsuku ezimbalwa, isisombululo asibonakali. Imhlophe noma i-turbid, kodwa isacacile kakhulu, lowo ngumkhiqizo ongcono!


Isikhathi sokuthumela: Dec-14-2022
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