Txhim kho cov nyhuv ntawm precipitated silica ntawm silicone roj hmab
Piv nrog rau silicone roj hmab compound reinforced nrog fumed silica, lub compound reinforced nrogprecipitated silica rau silicone roj hmabTuam Tshoj Chaw tsim tshuaj paus muaj me ntsis qis zog txhua yam, tsis zoo dielectric zog, tshwj xeeb tshaj yog tom qab ntub dej, tab sis zoo dua tshav kub aging kuj, thiab ntau dua nqi ntawm compound. Thaum lub zog txhua yam ntawm cov khoom tsis siab, precipitated silica lossis fumed silica tuaj yeem siv ua ke. Kev ua haujlwm ntawm precipitated silica yog cuam tshuam los ntawm nag lossis daus tej yam kev mob xws li acidity thiab kub.
Dawb carbon dub rau silicone roj hmabtuaj yeem kho los ntawm cov khoom sib xyaw tsim nyog los tsim cov tshuaj hydrophobic nto. Cov kev kho mob feem ntau suav nrog cov txheej txheem ua kua theem thiab cov txheej txheem roj. Cov txheej txheem ntawm cov txheej txheem ua kua yog yooj yim los tswj, cov khoom zoo yog ruaj khov, thiab cov nyhuv kho tau zoo, tab sis cov txheej txheem nyuaj, thiab cov kuab tshuaj yuav tsum tau rov ua dua tshiab; Cov txheej txheem kev kho roj yog yooj yim, tab sis qhov zoo ntawm cov khoom tsis ruaj khov txaus thiab cov nyhuv kho tsis zoo.
Tus neeg saib xyuas kev kho deg yog cov ntsiab lus siv los ua tus neeg sawv cev kho deg Muaj cov hauv qab no uas tuaj yeem cuam tshuam nrog pawg hydroxyl nyob rau saum npoo ntawm silica:
1) cawv 2) chlorosilane 3) alkoxysilane 4) hexamethyldisilane 5) silazane.
Lub zog txhawb zog ntawm silica ntawm silicone roj hmab yog suav tias yog muaj ob hom hauv qab no.
a. Cov roj hmab yog adsorbed los ntawm cov muab tub lim, uas adsorb lub polymer, kom cov roj hmab molecular saw segments ncaj qha nyob ze ntawm lub muab tub lim los yog taw qhia raws tus muab tub lim nto los yog khaws cia los ntawm muab tub lim aggregate.
b. Kev sib xyaw ntawm cov roj hmab thiab cov khoom muab tub lim kev sib xyaw ua ke ntawm cov khoom muab tub lim thiab cov khoom siv polymer ua kom muaj kev sib txuas zoo thiab cov khoom siv polymer entanglement ntawm muab tub lim.
Raws li ob txoj haujlwm saum toj no, silica tuaj yeem txhawb nqa silicone roj hmab.
Vim yog txoj kev tsim khoom sib txawv, acidity thiab alkalinity ntawm cov pa roj carbon dub yog txawv. Fumed silica yog acidic, thaum precipitated silica yog alkaline. Tus nqi pH ntawm lub purest HCI dawb fumed silica yog 6, uas yog tshwm sim los ntawm dissociation ntawm hydroxyl pawg nyob rau saum npoo ntawm silica nyob rau hauv dej los tsim h ntxiv. Thaum tus nqi pH qis dua 4.6, nws yog vim HCI hneev sab laug los ntawm qhov kub-kub hydrolysis.