Cov nyhuv ntawm Graphene Ntawm Hloov Kho Asphalt Microstructures Raws li Atomic Force Microscopy Ⅱ

3.4. Kev Sib Tham ntawm Asphalt Microstructure Raws li Liquid-Solid Phase Transformation Theory

Thaum lub caij txias, qee cov khoom ntawm molten asphalt tuaj yeem dhau mus rau theem ua kua-khoomkev hloov pauv, uas ua rau theem sib cais hauv asphalt. Qhov "nplua nuj qauv" yog qhov tshwm simntawm theem sib cais hauv asphalt. Raws li Gibbs, cov txheej txheem hloov theem tuaj yeem ua taucategorized ua ob, piv txwv li, nucleation-loj theem hloov pauv thiab txuas mus ntxiv.

Nyem qhov no kom tau txais cov ntaub ntawv ntau ntxiv txog Cistanche tshuaj ntsuab rau kev laus

Daim duab 6.Qhov siab faib ntawm asphalt micromorphology

3.4. Kev sib tham ntawm Asphalt Microstructure Basedntawm Liquid-Solid Phase Transformation Theory

Nyob rau hauv peb lub tswv yim, tsim ntawm "bee structures" thiab cov nyhuv ntawm graphene ntawm lub"bee structures" tuaj yeem piav qhia siv cov basic theory of "kua-solid phase transition". Raws li thermodynamic equilibrium txoj kev xav, ib theem kev hloov yuav tshwm sim rautsim ib theem tshiab thaum cov khoom txiased mus rau theem hloov pauv kub. Raws liDaim duab 6.Qhov siab faib ntawm asphalt micromorphology.3.4.1. Kev tsom xam ntawm "Bee Structure" TsimQhov tsim ntawm "nplua nuj qauv" tau sib cav, thiab nyob rau hauv peb lub tswv yim, lub "nplua nujcov qauv" ntawm asphalt yog vim siv quav ciab crystallization los yog cov koom haum koom nrog siv quav ciab thiabLwm cov pob zeb (xws li asphaltenes thiab modififiers). Thaum lub sij hawm khov ntawm asphalt, crudethiab cov roj residue-hydrocarbon sib tov nrog cov ntsiab lus siab melting muaj peev xwm los nagntawm crystallization - yog sau ua ke siv quav ciab. Wax yog qhov tseem ceeb rau kev tsim ntawm "nplua nujqauv." Cov tsos ntawm koob-flake crystals tom qab txias qhia tias muajmicrocrystalline wax hauv asphalt [37].

Wax crystallization cuam tshuam nrog kev hloov pauv ntawm lub embryo nuclear mus rau ib tug siv lead ua nucleus, ua raws li siv lead ua. Thaum lub caij txias, cov alkane molecules uas tau muab faibRandomly nyob rau hauv molten asphalt hloov los ntawm lub siab dawb-zog lub xeev (kua xeev) mus rau ib tug tsawg.lub xeev dawb-zog (crystalline xeev), uas cov alkane molecules nyob rau hauv lub luv luv.Cov txheej txheem ntawm kev tsim cov nucleus embryo ntawm "nuclear embryo", uas pab txhawbqhov ntxiv tsim ntawm ib tug ruaj khov crystal nucleus. Lub embryo nuclear yog qhov yuav tsum tau ua ua ntejkev tsim kho ntawm ib tug nucleus. Txawm li cas los xij, lub embryo nuclear yuav tawg yog tias qhov kub thiab txiasnce, whereas nws yuav tsim ib tug ruaj khov nucleus uas yuav loj thiab loj hlob muaju yog hais tias tusyaj tseem yuav txias. Cov txheej txheem crystallization suav nrog kev tsim nucleationthiab kev loj hlob ntawm cov nplej, ob qho tib si uas yuav tsum tau muaj qhov tsim nyog supercooling degree. Raws li covkub txo, cov molecules yuav undergo ib nruam txuas-pob txha thiabtawg-txuas cov txheej txheem los tsim cov ntsiab lus lattice kom txog thaum muaj qhov loj me me (ib qho tshiabruaj khov lub xeev), piv txwv li, ib tug crystal nucleus [38]. Thaum kawg, lwm cov molecules nyob ib puag ncig yuav ib txwmnpog cov ntsiab lus siv lead ua lattice thiab maj mam tsim cov qauv nyias nyias uas ze rausiv lead ua nucleus thiab ua rau cov siv lead ua nucleus tsim los ua ib rab koob zoo li siv lead ua.

Kev loj hlob ntawm cov siv lead ua tshwm sim hauv thaj av uas lub zog polymerization ntawmcov siv lead ua thiab dawb paraffin yog qhov loj tshaj plaws, uas ua rau muaj kev loj hlob sai ntawm daim ntawvqauv nyob rau sab ntawm lub crystal nucleus. Hauv lwm cov khoom ntawm microcrystallinewax thiab asphalt, asphaltene molecules ua lub hauv paus rau accumulating siv lead uapawg thiab tom qab ntawd txuas ntxiv txhim kho lawv mus rau "cov qauv muv." Thaum lub asphalt system yogtxias kom qis dua qhov kub ntawm crystallization, cov roj hauv asphalt ntawm ob sab ntawm lubdaim ntawv ncov yuav nce raws lub ncov, uas tuaj yeem suav hais tias yog qhov tshwm sim capillary hauvmolten asphalt [39]. Daim duab7 qhia ib daim duab schematic ntawm nag los ntawm "ntubNyob rau hauv lub xeev molten, asphaltic Cheebtsam (saturates, aromatics, resins, thiabasphaltene) sib tov rau hauv lub xeev homogeneous. Tom qab ntawd, los ntawm kev hloov kho, lubgraphene modifier yog uniformly dispersed nyob rau hauv molten asphalt los ua ib homogeneousqhov system. Thaum lub caij txias, graphene thiab asphaltenes yuav dhau los ua qhov chaw nucleation, thiab covwax yuav crystallize yooj yim, yog li ua rau "ntub qauv."

3.4.2. Cov nyhuv ntawm Graphene rau ntawm Bee Structures ntawm Asphalt

Cov lus xaus dhau los tau qhia tias qhov hloov kho graphene "bee structures" appeared nyob rau hauv ib tug ntau dua thiab tsawg tshaj li cov asphalt puag. Qhov rauMation ntawm ib tug siv lead ua nucleus yog thawj kauj ruam hauv crystallization, thiab cov txheej txheem nucleationtuaj yeem muab faib ua inhomogeneous thiab homogeneous nucleation raws li siv lead uanucleation txoj kev xav. Homogeneous nucleation hais txog tib qhov tshwm sim ntawm nucleus generation nyob rau hauv undercooled melts. Meanwhile, inhomogeneous nucleation hais txog ib qho rautxheej txheem mating tau yooj yim los ntawm ntau txoj haujlwm catalytic xws li nto, interface,tawg, thiab phab ntsa.

Lub cev ntawm qhov ruaj khov graphene hloov kho yuav dhau los ua qhov chaw catalytic rau nucleustsim nyob rau hauv hloov kho asphalt, thiab qhov no yog cais nyob rau hauv inhomogeneous nucleation.Kev koom ua ke ntawm graphene muab ntau qhov chaw nucleation, thiab cuam tshuam rauvide tsis tu ncua (spherical) templates uas ciab molecules tuaj yeem tso [40].Lub barrier ntawm inhomogeneous nucleation (∆Gk*) yog tsawg tshaj li ntawm homogeneous nucleation(∆Gk), thiab kev sib raug zoo muaj nyob rau hauv asphalt, raws li qhia nyob rau hauv Equation (3), qhov twgθreprexa lub kaum sab xis ntawm lub hau-puab nucleus thiab lub tiaj tus substrate, raws li tau piav qhia hauvclassical nucleation txoj kev xav. fig 8 shnws tus qauv cap-shaped inhomogeneousnucleation.Cosθtuaj yeem suav los ntawm Young's equation (Equation (4)). Hauv kab zauv 4, nl, sl,thiab snxa mus rau interfacial dawb energies ntawmlub nucleus thiab kua, substratethiabsubstrate thiab nucleus, feem. f(0) tuaj yeem tau los ntawm Equation (5) ntawm kev sib raug zoo geometric ntawm tus qauv cap, thiab nws tus nqi tsawg dua lossis sib npaug rau 1.

Thaum cov crystal nucleus tsim rau ntawm tus neeg sawv cev nucleating, lub nucleation barriertxo nrog lub kaum sab xis (θ), thiab inhomogeneous nucleation barrier yog qis duatshaj qhov homogeneous nucleation barrier, uas pab txhawb crystallization. Hauv lub hauv pausasphalt, asphaltene tuaj yeem ua tus neeg sawv cev nucleating. Los ntawm qhov sib txawv, hauv graphene-hloov khoasphalt, uniformly dispersed graphene nyob rau hauv asphalt yuav qhia nws lub luag hauj lwm raws li ib tug nucleating neeg sawv cevnrog asphaltene. Txawm hais tias siv quav ciab tuaj yeem raug tshem tawm ntawm inhomogeneous nucleation hauv ob qho tib sipuag thiab hloov asphalt, tus naj npawb ntawm nucleating tus neeg sawv cev hais nyob rau hauv ob qho tib si yuav txawv.Nyob rau hauv peb lub tswv yim, graphene modifier yuav ua hauj lwm raws li ib tug ntxiv dispersed nucleationqhov chaw uas pab kom tsim tau ib tug loj tus naj npawb ntawm me wax crystals [41]. Yog li ntawd,tus naj npawb ntawm "cov qauv muv" hauv graphene-hloov asphalt yuav siab dua li ntawdntawm lub hauv paus asphalt. Tsis tas li ntawd, graphene tuaj yeem ua rau qis dua "tus qauv muv" ntimvim feem ntau yog tsim los ntawm ib qho kev sib cog lus gel network hauv kev hloov khoasphalt. Nyob rau hauv peb lub tswv yim, tsim ntawm "nplua nuj qauv" yog categorized nyob rau hauv diffusiveKev hloov pauv theem, thiab qhov nce viscosity ntawm hloov kho asphalt cuam tshuam qhov diffusion thiabkev hloov ntawm wax molecules

Kev loj hlob theem ntawm "nplua nuj qauv" tuaj yeem piav qhia raws li diffusion txoj kev xav.Cov lus piav qhia ntxaws tau nthuav tawm hauv peb txoj kev tshawb fawb dhau los [27]. Hauv asphalt, qis duaviscosity ua rau tsawg dua kev sib cuam tshuam ntawm intermolecular, whereas me me resistant quab yuam mus raumigration ua rau muaj ntau dua molecular migration rate, uas pab txhawb kev tsiv teb tsaws ntawmasphalt Cheebtsam. Lub viscosity ntawm lub hauv paus asphalt yog tsawg dua li ntawm graphene-hloovasphalt. Cov khoom siv quav ciab tuaj yeem txav tau sai sai hauv lub hauv paus asphalt, yog li ntawdpab txhawb txoj kev loj hlob ntawm "nplua nuj qauv."

Meanwhile, tus naj npawb ntawm nucleationcov chaw hauv lub hauv paus asphalt tsawg dua li ntawm graphene-hloov asphalt. Yog li ntawd,cov asphalt "nplua nuj" ntawm lub hauv paus asphalt kom loj, thiab lawv cov kev faib tawm yogtawg tawg. Lub caij no, viscosity ntawm kev hloov kho asphalt yog siab, ua rau qhov qismigration ceev ntawm wax molecules. Tsis tas li ntawd, graphene li asphaltene tuaj yeem pabraws li qhov chaw nucleation thiab impede particle migration. Cov xwm txheej saum toj no tuaj yeem ua rau covntau kom muaj nuj nqis thiab me me ntawm "cov qauv muv" hauv kev hloov kho asphalt

Lub micromorphology ntawm unaged thiab laus puag asphalt thiab graphene-hloov liphalt tau tshawb xyuas los ntawm AFM. Cov kev hloov pauv micrograph tau muab piv thiab txheeb xyuas.Kev tsim mechanism ntawm asphaltic "nplua nuj qauv" thiab cov nyhuv ntawm graphene ntawm lub"bee structures" tau tham txog. Lub ntsiab lus xaus tau yog raws li nram no: