2024 Tus sau: Elizabeth Oswald | [email protected]. Kawg hloov kho: 2024-01-13 00:07
Nyob rau hauv rooj plaub ntawm bakelite phenol thiab formaldehyde condense los tsim cov monomer muab H2O raws li cov khoom lag luam. Bakelite tseem hu ua co-polymer. Cov tshuaj tiv thaiv: Phenol reacts nrog formaldehyde los tsim o-Hydroxy methyl phenol.
Dab tsi yog cov khoom lag luam tsim thaum lub sijhawm npaj ntawm Bakelite polymer?
Bakelite yog dab tsi? Bakelite, uas tseem hu ua 'khoom siv ntawm ib txhiab siv' yog tshuaj hu ua polyoxybenzyl methylene glycol anhydride. Nws yog ib qho thermosetting phenol-formaldehyde resin tsim los ntawm condensation cov tshuaj tiv thaiv ntawm phenol nrog formaldehyde.
Bakelite yog dab tsi?
Ib qho nyuaj, infusible, thiab chemically resistant yas, Bakelite yog raws li ib tug tshuaj ua ke ntawm phenol thiab formaldehyde (phenol-formaldehyde resin), ob lub tebchaw uas tau muab los ntawm thee. tar thiab ntoo cawv (methanol), raws li lub sijhawm ntawd.
Leej twg tsim Bakelite?
Tus kws tshuaj ntsuam hauv Belgian yug thiab ua lag luam Leo Baekeland tau tsim Bakelite, thawj cov khoom siv hluavtaws ua ntej. Cov khoom muaj yeeb yuj ua los ntawm Bakelite-jewelry, xov tooj, xov tooj cua, thiab billiard balls, kom lub npe tsuas yog ob peb lub neej txhua hnub nyob rau hauv thawj ib nrab ntawm lub xyoo pua 20th.
Vim li cas peb thiaj tsis siv Bakelite?
Bakelite daim ntawv thov kev txuag tau raug txiav tawm hauv 1940s vim tias qee qhov tsis zoo uas sai sai nopom meej. Qhov tsis muaj cov ntaub ntawv thiab cov ntaub ntawv cuam tshuam txwv tsis pub muaj qhov kev xav ntawm qhov nws siv thiab nyob rau hauv lub koom haum twg.
Pom zoo:
Pob lub sij hawm tso tsheb hlau luam puas tas sij hawm?
Tsis yog, helium tsis tas sij hawm. Koj yuav tsum kaw lub valve kom nruj lossis helium yuav xau dhau sijhawm. Puas yog Balloon Time tanks rov ua dua tshiab? Yog lawm, Balloon Time tanks tuaj yeem rov ua dua tshiab. Lub sijhawm balloon lub tank ntev npaum li cas?
Rau tus neeg muag khoom lub sij hawm cov khoom muag yog hais txog?
Cov khoom lag luam yog tus nqi ntawm cov khoom ntawm tes thiab muaj muag rau txhua lub sijhawm. Cov khoom muag khoom muag (tseem hu ua Inventory) yog ib qho cuab tam tam sim no nrog tus nqi debit ib txwm txhais tau tias tus debit yuav nce thiab credit yuav txo.
Lub sij hawm spur ntawm lub sij hawm los ntawm qhov twg?
Ib tug spur yog ib tug spiked txuas rau ntawm ib tug caij tsheb kauj vab uas yog siv los yaum tus nees mus rau hauv kev txiav txim. Nyob rau hauv thaum ntxov 1500s, kab lus ntawm lub spur txhais tau hais tias nyob rau hauv ceev ceev. Cov lus no tau hloov zuj zus mus rau niaj hnub no, nyob rau lub sijhawm tam sim no, thawj zaug siv ib ncig ntawm 1800 los txhais tau tias ua ib yam dab tsi tsis tau xav txog, ua kom tsis muaj zog.
Formula rau lub sij hawm lub sij hawm seem?
Tus qauv ntawm lub sijhawm yog muab los ntawm [M 0 L 0 T 1 . Or, T=√[M 0 L 1 T 0 ] × [M 0 L 1 T - 2 - 1 =√[T 2 ]=[M 0 L 0 T 1 ]. Yog li ntawd, lub sij hawm yog dimensionally sawv cev li [M 0 L 0 T 1]
Puas lub sij hawm mus sij hawm ntev li qub?
Qhov ntev ntawm kev coj khaub ncaws txawv ntawm poj niam mus rau poj niam, tab sis qhov nruab nrab yog yuav tsum muaj lub caij nyoog txhua 28 hnub. Lub voj voog tsis tu ncua uas ntev dua lossis luv dua li qhov no, txij li 21 txog 40 hnub, yog qhov qub.
