Cov khoom sau ua rau tus cwj pwm crystallization ntawm cov polymer li cas?

Xyoo 1980s, kev tshawb pom cov khoom zoo heev ntawm nylon 6/clay composites ua rau muaj kev tshawb fawb ntau yam txog cov polymer composites uas muaj cov khoom puv thiab kev nkag siab tshiab txog lub luag haujlwm ntawm cov khoom sau hauv cov polymers. Nov yog saib ntawm cov nyhuv ntawm cov khoom sau rau ntawm tus cwj pwm crystallization ntawm cov polymers.

Kev cuam tshuam ntawm cov khoom sau rau ntawm cov qauv siv lead ua ntawm cov polymers

Qhov ntxiv ntawm cov fillers cuam tshuam rau cov crystalline morphology ntawm cov polymer:

Cov polymers crystalline tsim cov qauv crystalline sib txawv nyob rau hauv cov xwm txheej crystallization sib txawv, thiab cov siv lead ua spherical yog ib qho ntawm cov yam ntxwv tseem ceeb tshaj plaws ntawm polymer crystallization. Nyob rau hauv cov xwm txheej molding thiab ua cov txheej txheem ib txwm muaj, cov polymers crystalline feem ntau tsim cov qauv crystalline spherical.

Qhov ntxiv ntawm cov khoom sau ua lub luag haujlwm hauv kev sib txawv ntawm cov nucleation thiab kev ua kom zoo ntawm cov nplej:

Cov siv lead ua spherical loj thiab tsis tshua muaj dhau los ua me thiab compact, thiab kev ua kom zoo ntawm cov siv lead ua spherical thiab kev txhim kho cov khoom siv tawv yog qhov zoo thiab tuaj yeem yog ib txoj hauv kev zoo rau kev ua kom cov polymers tawv.

Qhov sib xws ntawm cov khoom sau nrog cov resin matrix kuj muaj qhov cuam tshuam rau cov qauv crystalline:

Piv txwv li, Qiao Fang et al. pom tias cov organicized montmorillonite rhuav tshem cov qauv siv lead ua ke ntawm nylon 6, feem ntau vim tias cov nylon 6 molecules muaj cov nyhuv sib txuas nrog cov organicized montmorillonite particles, yog li ntawd kev txav mus los ntawm nylon 6 molecular saw segments raug cuam tshuam hauv cov txheej txheem crystallization, thiab nws nyuaj rau loj hlob hauv kev sib npaug thiab tsis tu ncua raws li kev taw qhia radial, yog li ntawd cov txheej txheem kev loj hlob crystallization raug cuam tshuam, yog li tsim cov siv lead ua tsis tiav.

Thaum lub sijhawm molding cov fibrous filled polymer composites, cov fibers yuav ua lub luag haujlwm nucleation thiab cov spherical crystals tsis muaj cov xwm txheej rau peb-seem kev loj hlob thaum lub sijhawm loj hlob, uas tom qab ntawd siv daim ntawv ntawm columnar kev loj hlob, piv txwv li, kev loj hlob ib-seem uas tsim cov transverse crystals.

Piv txwv li:

Cov neeg sawv cev nucleating yog ib pawg ntawm cov tshuaj uas tuaj yeem hloov pauv tus cwj pwm crystallization ntawm cov resins thiab hloov pauv cov qauv me me ntawm cov polymers kom muab cov khoom tshiab thiab cov haujlwm tshiab rau lawv, thiab yog ib qho kev tshawb fawb kub tam sim no hauv tsev thiab txawv teb chaws.

Txoj kev ua haujlwm: Hauv lub xeev molten, raws li tus neeg sawv cev nucleating muab cov nuclei xav tau, cov polymer hloov pauv los ntawm homogeneous nucleation mus rau heterogeneous nucleation, uas ua kom nrawm dua qhov crystallization tus nqi thiab txhim kho cov qauv noob, thiab tseem txhim kho qhov rigidity ntawm cov khoom.

Cov neeg sawv cev nucleating feem ntau tuaj yeem muab faib ua cov neeg sawv cev inorganic nucleating, cov neeg sawv cev organic nucleating thiab cov neeg sawv cev polymer nucleating. Cov neeg sawv cev nucleating nanoparticle tau dhau los ua qhov chaw kub rau kev tshawb fawb txog cov neeg sawv cev nucleating vim lawv muaj ntau lub hauv paus nquag ntawm qhov chaw, uas tuaj yeem sib txuas nrog lub substrate thiab muaj kev sib raug zoo dua, thiab cov khoom me me tsis yooj yim sib cais ua ke thaum raug rau lub zog sab nraud.

Cov nyhuv ntawm cov khoom sau rau ntawm polymer crystallization kinetics

Cov txheej txheem crystallization polymer muaj ob theem: nucleation thiab kev loj hlob. Tus qauv Avrami feem ntau yog siv los piav qhia txog cov txheej txheem isothermal crystallization ntawm cov polymers, thiab los ntawm kev nrhiav Avrami index n thiab crystallization rate tas mus li K, cov txheej txheem loj hlob ntawm cov siv lead ua thiab tus nqi ntawm kev loj hlob tuaj yeem tau los ntawm.

Mucha M et al. hauv lawv txoj kev kawm txog crystallization kinetics ntawm carbon black filled PP pom tias muaj ob kauj ruam crystallization phenomenon: nyob rau theem thaum ntxov ntawm crystallization cuam tshuam nrog heterogeneous nucleation ntawm PP, nucleation ntawm qhov chaw ntawm cov pa roj carbon black particles, tsis muaj kev sib tsoo ntawm nuclei tshwm sim nyob rau theem thaum ntxov ntawm crystallization thiab kev loj hlob tsis txwv; ua raws li los ntawm theem crystallization qeeb qhov twg qhov kev loj hlob qeeb los ntawm kev sib tsoo ntawm cov siv lead ua ke. Thaum ntxov ntawm crystallization, n yog li 2.0, thaum nyob rau theem tom qab ntawm crystallization, n yog li 3.0. Nws kuj pom tias qhov ntxiv ntawm cov pa roj carbon black sib txawv muaj cov teebmeem sib txawv ntawm cov nqi ntawm K thiab n. Ntawm tib qhov kub crystallization, tus nqi ntawm K nce nrog kev nce ntawm carbon black ntxiv.

Raws li Avrami equation, tus nqi n yuav tsum yog tus lej zoo tsawg dua lossis sib npaug rau 4. Hauv kev xyaum, tus nqi n ntawm cov txheej txheem crystallization ntawm polymers feem ntau yog tus lej decimal thiab zoo li sib npaug rau 5, uas qhia tau hais tias cov txheej txheem crystallization tiag tiag txawv ntawm Avrami equation thiab qhov tshwm sim ntawm kev crystallization theem nrab lossis kev sib tsoo siv lead ua ke tshwm sim.

Cov qauv crystalline ntawm cov polymers uas puv

Nyob rau hauv xyoo caum tsis ntev los no, kev tshawb fawb thiab kev sim tau ua pov thawj tag nrho tias muaj qhov chaw hloov pauv ntawm thaj chaw crystalline thiab amorphous ntawm crystalline. polymers, piv txwv li, ib txheej nruab nrab, hu ua theem crystalline - amorphous intermediate.

Cov nyhuv ntawm talc rau cov qauv ntawm thaj chaw crystalline, thaj chaw amorphous thiab theem nruab nrab ntawm cov polyethylene qis density (LDPE) tau raug tshuaj xyuas los ntawm dynamic two-dimensional infrared spectroscopy. Cov txiaj ntsig qhia tau tias qhov ntxiv ntawm talc ua rau muaj qee qhov kev hloov pauv hauv cov qauv crystalline ntawm LDPE, thiab nws tau xaus lus tias talc muaj kev sib txuas nrog thaj chaw crystalline tab sis tsis yog nrog theem amorphous, uas ua rau cov qauv qauv infrared.

Kev kawm txog cov nyhuv ntawm cov khoom sau rau ntawm tus cwj pwm crystallization ntawm cov polymers tuaj yeem ua rau nkag siab zoo dua txog cov txheej txheem crystallization thiab cov qauv crystallization ntawm cov polymers crystalline. Ntxiv mus, tus cwj pwm crystallization ntawm cov polymers uas tau sau tuaj yeem cuam tshuam ncaj qha rau cov khoom ntawm cov composites, yog li qhov no yuav tsum tau them sai sai rau.

Txawm hais tias muaj qee qhov kev nce qib hauv kev kawm txog cov nyhuv ntawm cov khoom sau rau ntawm cov khoom siv crystalline ntawm cov polymers, tseem muaj qhov tsis txaus ntawm kev tshawb fawb tob dua, kev ua haujlwm thiab kev tshawb fawb ntxaws ntxaws, thiab yog tias qhov no tuaj yeem ua tiav, nws yuav tsum ua rau muaj kev tshawb fawb ntau dua hauv kev npaj cov khoom siv thiab cov khoom.