iav hloov kub txhais
Iav-Transition Temperature (Tg), yog qhov kub ntawm lub polymer hloov ntawm lub xeev elastic mus rau lub xeev iav, Hais txog kev hloov pauv kub ntawm amorphous polymer (xws li cov tsis-crystalline hauv crystalline polymer) los ntawm lub xeev iav mus rau ib tug heev elastic xeev los yog los ntawm lub tom kawg mus rau lub qub.Nws yog qhov ntsuas kub qis tshaj plaws uas cov macromolecular ntu ntawm amorphous polymers tuaj yeem txav tau yooj yim.Feem ntau sawv cev los ntawm Tg.Nws txawv nyob ntawm txoj kev ntsuas thiab tej yam kev mob.
Qhov no yog ib qho tseem ceeb qhia txog kev ua tau zoo ntawm polymers.Saum toj no kub, lub polymer qhia elasticity;Hauv qab no qhov kub thiab txias, lub polymer qhia tau hais tias brittleness.Nws yuav tsum raug txiav txim siab thaum siv cov yas, roj hmab, hluavtaws fibers, thiab lwm yam. Piv txwv li, iav hloov kub ntawm polyvinyl chloride yog 80 ° C.Txawm li cas los xij, nws tsis yog qhov txwv siab ntawm cov khoom ua haujlwm kub.Piv txwv li, kev ua haujlwm kub ntawm cov roj hmab yuav tsum yog siab dua lub iav hloov pauv kub, txwv tsis pub nws yuav poob nws cov elasticity siab.
Vim tias hom polymer tseem tswj hwm nws qhov xwm txheej, emulsion kuj tseem muaj qhov hloov pauv iav, uas yog qhov qhia txog qhov nyuaj ntawm txheej zaj duab xis tsim los ntawm polymer emulsion.Lub emulsion nrog lub iav siab hloov pauv kub muaj txheej txheej nrog lub siab hardness, siab gloss, zoo stain tsis kam, thiab tsis yooj yim rau paug, thiab nws lwm yam khoom siv zoo sib xws.Txawm li cas los xij, cov iav hloov pauv kub thiab nws qhov tsawg kawg nkaus ntawm cov yeeb yaj kiab-tsim kub kuj tseem siab, uas ua rau muaj qee yam teeb meem siv rau qhov kub thiab txias.Qhov no yog qhov tsis sib xws, thiab thaum lub polymer emulsion nce mus txog qhov kub hloov pauv ntawm iav, ntau yam ntawm nws cov khoom yuav hloov tseem ceeb, yog li qhov tsim nyog iav hloov kub yuav tsum tau tswj.Raws li qhov kev txhawj xeeb ntawm polymer-hloov mortar, qhov siab dua ntawm iav hloov qhov kub, qhov siab dua lub zog ntawm cov mortar hloov.Qhov qis dua qhov hloov pauv iav, qhov zoo dua qhov kev ua haujlwm qis-kub ntawm cov mortar hloov kho.
Yam tsawg kawg nkaus zaj duab xis tsim kub txhais
Yam tsawg kawg nkaus Film Forming Temperature yog ib qho tseem ceebqhov taw qhia ntawm qhuav mix mortar
MFFT hais txog qhov ntsuas kub tsawg kawg nkaus uas cov khoom siv polymer hauv cov emulsion muaj kev txav mus los txaus rau agglomerate nrog ib leeg los tsim cov yeeb yaj kiab txuas ntxiv.Nyob rau hauv tus txheej txheem ntawm polymer emulsion tsim ib tug nruam txheej zaj duab xis, cov polymer hais yuav tsum tsim ib tug zoo packed txheej txheem.Yog li ntawd, nyob rau hauv tas li ntawd mus rau lub zoo dispersion ntawm lub emulsion, tej yam kev mob rau tsim ib tug nruam zaj duab xis kuj muaj xws li lub deformation ntawm cov polymer hais.Ntawd yog, thaum lub capillary siab ntawm cov dej ua rau muaj kev kub ntxhov ntawm cov thooj voos kheej kheej, qhov ze ntawm cov khoom kheej kheej raug teeb tsa, lub siab ntau dua.
Thaum cov particles tuaj rau hauv kev sib cuag nrog ib leeg, lub siab generated los ntawm volatilization ntawm cov dej quab yuam cov hais yuav tsum tau squeezed thiab deformed rau kev sib raug zoo nrog ib leeg los ua ib tug txheej zaj duab xis.Pom tseeb, rau cov emulsions nrog cov neeg ua haujlwm nyuaj, feem ntau ntawm cov khoom siv polymer yog cov thermoplastic resins, qhov kub thiab txias, qhov hnyav dua thiab qhov nyuaj yuav ua rau deform, yog li muaj teeb meem ntawm qhov tsawg kawg nkaus zaj duab xis-forming kub.Ntawd yog, qis dua qhov kub thiab txias, tom qab cov dej hauv emulsion evaporates, cov khoom polymer tseem nyob hauv lub xeev tsis sib xws thiab tsis tuaj yeem ua ke.Yog li ntawd, cov emulsion tsis tuaj yeem tsim cov txheej txheem txuas ntxiv vim yog dej evaporation;Thiab saum toj no qhov tshwj xeeb kub, thaum dej evaporates, cov molecules nyob rau hauv txhua lub polymer particle yuav nkag mus, diffuse, deform, thiab aggregate los ua ib tug nruam pob tshab zaj duab xis.Qhov kev txwv qis ntawm qhov kub ntawm cov yeeb yaj kiab tuaj yeem tsim tau yog hu ua qhov tsawg kawg nkaus zaj duab xis ua qhov kub.
MFFT yog qhov taw qhia tseem ceeb ntawmpolymer emulsion, thiab nws yog ib qho tseem ceeb tshwj xeeb uas yuav tsum tau siv emulsion thaum lub caij kub.Kev ntsuas tsim nyog tuaj yeem ua rau cov polymer emulsion muaj qhov tsawg kawg nkaus ntawm cov yeeb yaj kiab-tsim kub uas ua tau raws li qhov yuav tsum tau siv.Piv txwv li, ntxiv cov yas yas rau lub emulsion tuaj yeem ua rau cov polymer soften thiab txo qhov tsawg kawg nkaus ntawm zaj duab xis-forming kub ntawm emulsion, los yog kho qhov tsawg kawg nkaus film-forming kub.High polymer emulsions siv additives, thiab lwm yam.
MFFT ntawm LongouVAE redispersible latex hmoovFeem ntau ntawm 0 ° C thiab 10 ° C, ntau tshaj ib qho yog 5 ° C.Nyob rau hauv qhov ntsuas kub no, lubpolymer hmoovnthuav tawm cov yeeb yaj kiab tsis tu ncua.Ntawm qhov tsis sib xws, hauv qab no qhov kub thiab txias, zaj duab xis ntawm redispersible polymer hmoov yog tsis tas mus li thiab so.Yog li ntawd, qhov tsawg kawg nkaus zaj duab xis tsim kub yog qhov taw qhia uas sawv cev rau qhov kub thiab txias ntawm qhov project.Feem ntau hais lus, qhov tsawg kawg nkaus ntawm cov yeeb yaj kiab-tsim kub, qhov ua haujlwm tau zoo dua.
Qhov sib txawv ntawm Tg thiab MFFT
1. Cov iav hloov pauv kub, qhov kub ntawm cov khoom siv softens.Feem ntau yog hais txog qhov kub thiab txias uas amorphous polymers pib muag.Nws tsis tsuas yog cuam tshuam nrog cov qauv ntawm cov polymer, tab sis kuj rau nws qhov hnyav molecular.
2.Softening point
Raws li lub zog sib txawv ntawm cov khoom siv polymers, feem ntau cov ntaub ntawv polymer feem ntau tuaj yeem nyob hauv plaub lub xeev hauv qab no (los yog lub xeev cov tshuab): lub xeev iav, lub xeev viscoelastic, lub xeev elastic heev (lub xeev roj hmab) thiab lub xeev khov.Kev hloov iav yog qhov hloov pauv ntawm lub xeev siab heev thiab lub xeev iav.Los ntawm cov qauv molecular foundations, lub iav hloov pauv kub yog qhov tshwm sim ntawm kev so ntawm lub amorphous ntawm cov polymer los ntawm lub xeev khov mus rau lub xeev thawed, tsis zoo li theem.Muaj cov theem hloov pauv thaum lub sijhawm hloov pauv, yog li nws yog theem nrab hloov pauv (hu ua thawj hloov pauv hauv polymer dynamic mechanics).Hauv qab lub iav hloov pauv kub, cov polymer yog nyob rau hauv lub khob iav, thiab cov saw hlau molecular thiab ntu yuav txav tsis tau.Tsuas yog cov atoms (los yog pawg) tsim cov molecules vibrate ntawm lawv txoj haujlwm sib npaug;Thaum lub iav hloov pauv kub, txawm tias cov saw hlau molecular Nws txav tsis tau, tab sis cov saw ntu pib txav mus, uas qhia cov khoom muaj zog.Yog tias qhov kub thiab txias dua, tag nrho cov saw hlau molecular yuav txav mus thiab qhia cov khoom muaj kuab heev.Cov iav hloov pauv kub (Tg) yog ib qho tseem ceeb ntawm lub cev ntawm amorphous polymers.
iav hloov kub yog ib qho ntawm cov yam ntxwv kub ntawm polymers.Noj cov iav hloov pauv kub raws li tus ciam teb, polymers nthuav tawm cov khoom sib txawv ntawm lub cev: hauv qab lub iav hloov kub, cov khoom siv polymer yog yas;saum lub iav hloov kub, cov khoom siv polymer yog roj hmab.Los ntawm qhov kev xav ntawm kev siv engineering, kev txwv sab saud ntawm kev siv cov iav hloov pauv kub engineering plastics yog qhov txwv qis ntawm kev siv roj hmab lossis elastomers.
Post lub sij hawm: Jan-04-2024