Hydroxypropyl methylcellulose (HPMC) yog ib qho polymer uas siv tau ntau yam hauv ntau yam lag luam xws li tshuaj, khoom noj, kev tsim kho thiab tshuaj pleev ib ce. Cov khoom siv tseem ceeb uas siv los ua HPMC yog cellulose thiab propylene oxide.
1. Cellulose: lub hauv paus ntawm HPMC
1.1 Kev piav qhia txog cellulose
Cellulose yog cov carbohydrate nyuaj uas yog cov khoom tseem ceeb ntawm cov phab ntsa cell ntawm cov nroj tsuag ntsuab. Nws muaj cov saw hlau ntawm cov glucose molecules txuas ua ke los ntawm β-1,4-glycosidic bonds. Qhov muaj ntau ntawm cov hydroxyl pawg hauv cellulose ua rau nws yog cov khoom siv pib tsim nyog rau kev tsim ntau yam cellulose derivatives, suav nrog HPMC.
1.2 Kev yuav khoom cellulose
Cellulose tuaj yeem tau los ntawm ntau yam khoom siv cog qoob loo, xws li cov ntoo pulp, paj rwb linters, lossis lwm yam nroj tsuag fibrous. Cov ntoo pulp yog ib qho chaw dav vim nws muaj ntau, siv tau zoo, thiab ruaj khov. Kev rho tawm ntawm cellulose feem ntau cuam tshuam nrog kev rhuav tshem cov nroj tsuag fibers los ntawm ntau yam txheej txheem tshuab thiab tshuaj lom neeg.
1.3 Kev huv thiab cov yam ntxwv
Qhov zoo thiab qhov huv ntawm cellulose yog qhov tseem ceeb hauv kev txiav txim siab txog cov yam ntxwv ntawm HPMC cov khoom kawg. Cov cellulose ntshiab siab ua kom HPMC tsim tawm nrog cov khoom zoo sib xws xws li viscosity, solubility thiab thermal stability.
2. Propylene oxide: kev qhia txog hydroxypropyl pawg
2.1 Kev Taw Qhia Txog Propylene Oxide
Propylene oxide (PO) yog ib qho organic compound nrog cov tshuaj mis C3H6O. Nws yog ib qho epoxide, txhais tau tias nws muaj ib qho oxygen atom bonded rau ob lub carbon atoms sib ze. Propylene oxide yog cov khoom siv tseem ceeb rau kev tsim cov hydroxypropyl cellulose, uas yog ib qho nruab nrab rau kev tsim HPMC.
2.2 Cov txheej txheem hydroxypropylation
Cov txheej txheem hydroxypropylation cuam tshuam nrog cov tshuaj tiv thaiv ntawm cellulose nrog propylene oxide los qhia cov pab pawg hydroxypropyl rau ntawm cellulose backbone. Cov tshuaj tiv thaiv no feem ntau yog ua tiav nyob rau hauv qhov muaj cov catalyst yooj yim. Cov pab pawg Hydroxypropyl muab kev txhim kho solubility thiab lwm yam khoom zoo rau cellulose, ua rau muaj hydroxypropyl cellulose.
3. Methylation: Ntxiv cov pawg methyl
3.1 Cov txheej txheem Methylation
Tom qab hydroxypropylation, cov kauj ruam tom ntej hauv HPMC synthesis yog methylation. Cov txheej txheem cuam tshuam nrog kev qhia txog cov pab pawg methyl rau ntawm cellulose backbone. Methyl chloride yog cov tshuaj reagent siv rau qhov kev tshuaj tiv thaiv no. Qib ntawm methylation cuam tshuam rau cov khoom ntawm cov khoom kawg HPMC, suav nrog nws cov viscosity thiab gel tus cwj pwm.
3.2 Qib ntawm kev hloov pauv
Qhov degree of substitution (DS) yog qhov tseem ceeb rau kev ntsuas tus lej nruab nrab ntawm cov substituents (methyl thiab hydroxypropyl) ib chav anhydroglucose hauv cov saw cellulose. Cov txheej txheem tsim khoom raug tswj hwm kom ua tiav qhov kev ua tau zoo ntawm cov khoom HPMC.
4. Kev Ua Kom Huv Si thiab Kev Tswj Xyuas Zoo
4.1 Tshem tawm cov khoom seem
Kev tsim cov HPMC yuav ua rau muaj cov khoom seem xws li ntsev lossis cov tshuaj reagents tsis tau teb. Cov kauj ruam ntxuav suav nrog kev ntxuav thiab lim dej yog siv los tshem tawm cov khoom tsis huv no thiab ua kom cov khoom kawg huv si.
4.2 Kev ntsuas kev tswj xyuas zoo
Cov kev ntsuas tswj xyuas zoo nruj heev tau siv thoob plaws hauv cov txheej txheem tsim khoom kom ntseeg tau tias muaj kev sib xws thiab zoo ntawm HPMC. Cov txheej txheem tshuaj ntsuam xws li spectroscopy, chromatography thiab rheology yog siv los ntsuas cov yam ntxwv xws li qhov hnyav molecular, qib ntawm kev hloov pauv thiab viscosity.
5. Cov yam ntxwv ntawm Hydroxypropyl Methylcellulose (HPMC)
5.1 Cov khoom siv lub cev
HPMC yog hmoov dawb mus rau dawb tawm, tsis muaj ntxhiab nrog cov yam ntxwv zoo heev rau kev tsim zaj duab xis. Nws yog hygroscopic thiab yooj yim tsim cov gel pob tshab thaum dispersed hauv dej. Qhov solubility ntawm HPMC nyob ntawm qib ntawm kev hloov pauv thiab cuam tshuam los ntawm cov yam xws li kub thiab pH.
5.2 Cov qauv tshuaj lom neeg
Cov qauv tshuaj ntawm HPMC muaj cov cellulose backbone nrog hydroxypropyl thiab methyl substituents. Qhov piv ntawm cov substituents no, uas cuam tshuam rau qib ntawm kev hloov pauv, txiav txim siab txog cov qauv tshuaj tag nrho thiab yog li cov khoom ntawm HPMC.
5.3 Viscosity thiab rheological zog
HPMC muaj nyob rau hauv ntau qib nrog ntau yam viscosity. Qhov viscosity ntawm HPMC cov kev daws teeb meem yog qhov tseem ceeb hauv kev siv xws li tshuaj, qhov twg nws cuam tshuam rau qhov tso tawm ntawm cov tshuaj, thiab hauv kev tsim kho, qhov twg nws cuam tshuam rau kev ua haujlwm ntawm cov mortars thiab pastes.
5.4 Cov yam ntxwv ua zaj duab xis thiab ua kom tuab
HPMC siv dav ua cov zaj duab xis hauv cov tshuaj pleev xim thiab ua cov neeg sawv cev tuab hauv ntau yam qauv. Nws lub peev xwm tsim cov zaj duab xis ua rau nws muaj txiaj ntsig zoo hauv kev txhim kho cov txheej txheem tshuaj tswj kev tso tawm, thaum nws cov khoom tuab ua rau cov qauv thiab kev ruaj khov ntawm ntau yam khoom.
6. Daim ntawv thov ntawm hydroxypropyl methylcellulose
6.1 Kev lag luam tshuaj
Hauv kev lag luam tshuaj, HPMC siv los tsim cov tshuaj khov kho xws li cov ntsiav tshuaj thiab cov tshuaj ntsiav. Nws feem ntau siv ua tus neeg sawv cev rau cov khoom sib txuas, cov khoom tawg thiab cov tshuaj pleev xim. Cov khoom tswj kev tso tawm ntawm HPMC ua rau nws siv tau rau hauv cov tshuaj tso tawm tas mus li.
6.2 Kev lag luam tsim kho
Hauv kev tsim kho, HPMC siv ua tus neeg sawv cev khaws dej, ua kom tuab thiab nplaum rau cov khoom siv cement. Nws ua rau cov mortar ua haujlwm tau zoo dua, tiv thaiv kev poob qis hauv kev siv ntsug, thiab txhim kho kev ua haujlwm ntawm cov khoom siv hauv tsev.
6.3 Kev lag luam zaub mov
HPMC siv rau hauv kev lag luam khoom noj ua ib yam khoom ua kom tuab, ruaj khov thiab emulsifier. Nws lub peev xwm los tsim cov gels ntawm qhov tsis tshua muaj zog ua rau nws haum rau ntau yam kev siv, suav nrog cov kua ntses, cov kua ntses thiab cov khoom qab zib.
6.4 Cov tshuaj pleev ib ce thiab cov khoom siv tu tus kheej
Hauv cov tshuaj pleev ib ce thiab cov khoom siv tu tus kheej, HPMC pom muaj ntau yam qauv xws li tshuaj pleev, tshuaj pleev thiab tshuaj zawv plaub hau. Nws pab txhim kho qhov zoo nkauj, kev ruaj khov thiab kev ua tau zoo ntawm cov khoom no.
6.5 Lwm yam lag luam
HPMC muaj ntau yam siv tau rau lwm yam lag luam, suav nrog cov ntaub, xim thiab cov nplaum, qhov twg nws siv tau ua cov khoom hloov pauv rheology, tus neeg sawv cev khaws dej thiab cov khoom ua kom tuab.
7. Xaus Lus
Hydroxypropylmethylcellulose yog ib qho polymer uas siv tau ntau yam nrog ntau yam kev siv. Nws cov synthesis siv cellulose thiab propylene oxide ua cov khoom siv raw tseem ceeb, thiab cellulose raug hloov kho los ntawm hydroxypropylation thiab methylation cov txheej txheem. Kev tswj hwm cov khoom siv raw no thiab cov xwm txheej tshuaj tiv thaiv tuaj yeem tsim HPMC nrog cov khoom siv kho kom haum rau cov kev xav tau tshwj xeeb hauv kev lag luam. Yog li ntawd, HPMC ua lub luag haujlwm tseem ceeb hauv kev txhim kho kev ua tau zoo thiab kev ua haujlwm ntawm cov khoom thoob plaws kev lag luam. Kev tshawb nrhiav tas mus li ntawm cov ntawv thov tshiab thiab kev txhim kho cov txheej txheem tsim khoom pab HPMC txuas ntxiv ua lub luag haujlwm tseem ceeb hauv kev lag luam thoob ntiaj teb.
Lub sijhawm tshaj tawm: Lub Kaum Ob Hlis-28-2023