Hydroxypropyl Methylcellulose yog dab tsi los ntawm

Hydroxypropyl methylcellulose (HPMC) yog cov khoom siv hluav taws xob semisynthetic uas siv rau hauv ntau qhov kev lag luam, suav nrog kev tsim kho, khoom noj khoom haus, tshuaj, thiab cov khoom tu tus kheej. Nws muaj nuj nqis rau nws lub peev xwm los txhim kho rheological zog ntawm formulations, nrog rau nws compatibility nrog rau lwm cov khoom xyaw thiab nws cov toxicity tsawg. Yuav kom nkag siab tias HPMC tau tsim li cas, nws yog ib qho tseem ceeb ua ntej nkag siab txog cov qauv thiab cov khoom ntawm cellulose.

Cellulose yog ib txoj kab ntev ntawm cov piam thaj molecules uas pom nyob rau hauv cell phab ntsa ntawm cov nroj tsuag. Cov piam thaj molecules tau txuas ua ke los ntawm beta-1,4-glycosidic bonds, tsim cov saw hlau. Cov chains tau tuav ua ke los ntawm hydrogen bonds thiab Van der Waals rog los tsim cov qauv muaj zog, fibrous. Cellulose yog cov organic ntau tshaj plaws nyob rau hauv lub ntiaj teb, thiab nws yog siv nyob rau hauv ntau yam kev siv, xws li ntawv, textiles, thiab cov ntaub ntawv hauv tsev.

Txawm hais tias cellulose muaj ntau yam khoom muaj txiaj ntsig, nws feem ntau nruj heev thiab insoluble siv rau hauv ntau cov qauv. Txhawm rau kov yeej cov kev txwv no, cov kws tshawb fawb tau tsim ntau yam hloov pauv cellulose derivatives, suav nrog HPMC. HPMC yog tsim los ntawm kev hloov kho tej yam ntuj tso cellulose los ntawm ib tug series ntawm tshuaj tiv thaiv.

Thawj kauj ruam hauv kev ua HPMC yog kom tau txais cov khoom pib cellulose. Qhov no tuaj yeem ua tau los ntawm kev rho tawm cellulose los ntawm cov nroj tsuag xws li ntoo pulp, paj rwb, lossis xyoob. Cov cellulose yog tom qab ntawd kho nrog cov tshuaj alkaline, xws li sodium hydroxide lossis potassium hydroxide, kom tshem tawm cov impurities thiab rhuav tshem cov cellulose fibers rau hauv me me. Cov txheej txheem no hu ua mercerization, thiab nws ua rau cov cellulose reactive thiab hloov tau yooj yim dua.

Tom qab mercerization, cellulose yog reacted nrog ib tug sib tov ntawm propylene oxide thiab methyl chloride los qhia hydroxypropyl thiab methyl pawg mus rau lub cellulose qaum. Cov pab pawg hydroxypropyl tau ntxiv los txhim kho cov solubility thiab dej tuav cov khoom ntawm cellulose, thaum cov methyl pawg tau ntxiv los ua kom muaj kev ruaj ntseg thiab txo cov reactivity ntawm cellulose. Cov tshuaj tiv thaiv feem ntau yog ua nyob rau hauv lub xub ntiag ntawm ib tug catalyst, xws li sodium hydroxide los yog poov tshuaj hydroxide, thiab nyob rau hauv cov kev tswj ntawm kub, siab, thiab cov tshuaj tiv thaiv lub sij hawm.

Qib ntawm kev hloov pauv (DS) ntawm HPMC yog hais txog tus naj npawb ntawm hydroxypropyl thiab methyl pawg uas tau nkag mus rau hauv cov pob txha cellulose. DS tuaj yeem sib txawv raws li qhov xav tau ntawm HPMC thiab daim ntawv thov tshwj xeeb uas nws tau siv rau. Feem ntau, cov txiaj ntsig DS siab dua ua rau HPMC nrog cov viscosity qis dua thiab nrawm dua, thaum cov nqi DS qis dua ua rau HPMC nrog cov viscosity ntau dua thiab qeeb qeeb qeeb.

Tom qab cov tshuaj tiv thaiv tiav, cov khoom tsim tau raug ntxuav thiab qhuav los tsim HPMC hmoov. Cov txheej txheem purification yuav tshem tawm cov tshuaj tsis muaj tshuaj, cov kuab tshuaj seem, thiab lwm yam impurities los ntawm HPMC. Qhov no feem ntau yog ua los ntawm kev sib xyaw ua ke ntawm kev ntxuav, pom, thiab ziab cov kauj ruam.

Cov khoom kawg yog cov hmoov dawb rau cov hmoov dawb uas tsis muaj ntxhiab thiab tsis qab. HPMC yog soluble hauv dej thiab ntau cov kuab tshuaj organic, thiab nws tuaj yeem tsim cov gels, films, thiab lwm yam qauv nyob ntawm seb qhov kev siv. Nws yog non-ionic polymer, txhais tau hais tias nws tsis nqa cov nqi hluav taws xob, thiab nws feem ntau suav tias yog tsis muaj tshuaj lom thiab muaj kev nyab xeeb rau kev siv ntau yam kev siv.

HPMC yog siv nyob rau hauv ntau yam formulations, nrog rau cov xim, cov nplaum, sealants, tshuaj, thiab khoom noj khoom haus. Hauv kev tsim kho, HPMC feem ntau yog siv los ua cov thickener, binder, thiab zaj duab xis-yav dhau los hauv cov khoom siv cementitious thiab gypsum, xws li mortars, grouts, thiab sib koom ua ke.