Ubushyuhe bwikirahure busobanura
Ubushyuhe bw'Ibirahure-Inzibacyuho (Tg) ， ni ubushyuhe aho polymer ihinduka kuva muri elastike ikajya mubirahuri ， Yerekeza ku bushyuhe bwinzibacyuho ya polymer amorphous (harimo igice kitari kristaline muri polymer kristaline) kiva mubirahuri kuri elastike cyane cyangwa kuva mubihe byanyuma. Nubushyuhe bwo hasi cyane aho macromolecular ibice bya amorphous polymers bishobora kugenda mubuntu. Mubisanzwe Uhagarariwe na Tg. Iratandukanye bitewe nuburyo bwo gupima nuburyo bimeze.
Iki nigikorwa cyingenzi cyerekana polymers. Hejuru yubushyuhe, polymer yerekana elastique; munsi yubushyuhe, polymer yerekana ubugome. Igomba gusuzumwa mugihe ikoreshwa nka plastiki, reberi, fibre synthique, nibindi. Urugero, ubushyuhe bwikirahure bwa polyvinyl chloride ni 80 ° C. Ariko, ntabwo arirwo rugabano rwo hejuru rwibicuruzwa bikora. Kurugero, ubushyuhe bwakazi bwa reberi bugomba kuba hejuru yubushyuhe bwikirahure, bitabaye ibyo bizatakaza ubuhanga bukomeye.
Kubera ko ubwoko bwa polymer bugikomeza imiterere yabwo, emulion nayo ifite ubushyuhe bwikirahure bwikirahure, nikimenyetso cyerekana ubukana bwa firime ya coating yakozwe na polymer emulsion. Emuliyoni hamwe nubushyuhe bwo hejuru bwikirahure ifite igifuniko gifite ubukana bwinshi, urumuri rwinshi, irwanya ikizinga cyiza, kandi ntabwo byoroshye guhumana, kandi nibindi bikoresho byubukanishi nibyiza. Nyamara, ubushyuhe bwikirahure nubushyuhe bwacyo bwo gukora firime nabyo biri hejuru, bizana ibibazo bimwe na bimwe byo gukoresha mubushyuhe buke. Ibi ni ukuvuguruzanya, kandi iyo polymer emulion igeze ku bushyuhe bwikirahure runaka, ibintu byinshi bizahinduka byingenzi, bityo ubushyuhe bukwiye bwikirahure bugomba kugenzurwa. Kubijyanye na polymer-yahinduwe minisiteri, hejuru yubushyuhe bwikirahure, niko imbaraga zo kwikuramo za minisiteri zahinduwe. Hasi yubushyuhe bwikirahure, nibyiza imikorere yubushyuhe buke bwa minisiteri yahinduwe.
Filime ntarengwa isobanura ubushyuhe
Ubushyuhe bwa Firime Ntarengwa ni ngombwaicyerekezo cya minisiteri yumye
MFFT bivuga ubushyuhe buke aho polymer ibice muri emulsiyo bifite umuvuduko uhagije wo guterana hamwe kugirango bikore firime ikomeza. Muburyo bwa polymer emulion ikora firime ikomeza, ibice bya polymer bigomba gukora ibintu byegeranye cyane. Kubwibyo, usibye gukwirakwiza neza kwa emulsiyo, ibisabwa kugirango ukore firime ikomeza harimo no guhindura ibice bya polymer. Nukuvuga ko, iyo umuvuduko wa capillary wamazi utanga umuvuduko mwinshi hagati yimiterere ya serefegitura, uko uduce duto duto dutunganijwe, niko umuvuduko wiyongera.
Iyo ibice bihuye, umuvuduko ukomoka ku guhindagurika kwamazi uhatira ibice guhindagurika no guhindurwa kugirango bihuze hamwe kugirango bikore firime. Ikigaragara ni uko kuri emulisiyo hamwe nibintu bigoye cyane, ibyinshi mubice bya polymer nibisigara bya termoplastique, ubushyuhe buke, niko bigenda bikomera kandi bigoye guhinduka, bityo hakaba ikibazo cyubushyuhe buke bwo gukora firime. Ni ukuvuga, munsi yubushyuhe runaka, nyuma yamazi yo muri emulsiyo amaze guhinduka, ibice bya polymer biracyari muburyo butandukanye kandi ntibishobora guhuzwa. Kubwibyo, emulion ntishobora gukora igifuniko gikomeza kubera guhumeka kwamazi; Hejuru yubushyuhe bwihariye, mugihe amazi azimye, molekile muri buri gice cya polymer izinjira, ikwirakwira, ihindurwe, kandi yegeranye kugirango ikore firime ikomeza. Iyi mipaka yo hasi yubushyuhe firime ishobora gukoreramo yitwa byibura firime ikora ubushyuhe.
MFFT ni ikimenyetso cyingenzi cyapolymer emulsion, kandi ni ngombwa cyane gukoresha emuliyoni mugihe cyubushyuhe buke. Gufata ingamba zikwiye birashobora gutuma polymer emulsiyo igira ubushyuhe buke bwo gukora firime bujuje ibisabwa. Kurugero, kongeramo plasitike kuri emulsion birashobora koroshya polymer kandi bikagabanya cyane ubushyuhe buke bwo gukora firime ya emulsiyo, cyangwa guhindura ubushyuhe buke bwo gukora firime. Amuliyeri yo hejuru ya polymer akoresha inyongeramusaruro, nibindi.
MFFT ya LongouVAE isubirwamo ifu ya latexmuri rusange hagati ya 0 ° C na 10 ° C, ibisanzwe ni 5 ° C. Kuri ubu bushyuhe ,.ifu ya polymerYerekana firime ikomeza. Ibinyuranye, munsi yubushyuhe, firime yifu ya polymer isubirwamo ntigikomeza kandi iracika.Nuko rero, ubushyuhe buke bwa firime bugaragaza ubushyuhe bwerekana ubushyuhe bwubaka bwumushinga. Mubisanzwe, nukuvuga ubushyuhe buke bwo gukora firime, niko gukora neza.
Itandukaniro riri hagati ya Tg na MFFT
1. Ubushyuhe bwikirahure, ubushyuhe ibintu byoroha. Ahanini bivuga ubushyuhe polimeri amorphous itangira koroshya. Ntabwo ifitanye isano gusa nuburyo bwa polymer, ahubwo nuburemere bwa molekile.
2. Ingingo yoroshye
Ukurikije imbaraga zinyuranye za polymers, ibikoresho byinshi bya polymer mubisanzwe birashobora kuba mubintu bine bikurikira (cyangwa imiterere yubukanishi): imiterere yikirahure, imiterere ya viscoelastique, imiterere ya elastike cyane (reta ya reberi) nuburyo bwo gutembera neza. Inzibacyuho yikirahure ninzibacyuho hagati ya elastike cyane na reta yikirahure. Uhereye ku miterere ya molekulire, ubushyuhe bwikirahure ni ibintu byo kuruhuka igice cya amorphous igice cya polymer kuva muri leta yakonje kugera kuri leta yashonze, bitandukanye nicyiciro. Hariho ubushyuhe bwo guhindura ubushyuhe mugihe cyo guhinduka, nuko rero ni icyiciro cya kabiri cyo guhinduka (bita impinduka yibanze muri polymer dinamike). Munsi yubushyuhe bwikirahure, polymer iri mubirahuri, kandi iminyururu ya molekile nibice ntibishobora kugenda. Gusa atome (cyangwa amatsinda) bigize molekile zinyeganyega kumwanya wazo uringaniye; mugihe ubushyuhe bwikirahure, nubwo iminyururu ya molekuline Ntishobora kugenda, ariko ibice byurunigi bitangira kugenda, byerekana ibintu byoroshye bya elastique. Niba ubushyuhe bwongeye kwiyongera, urunigi rwose rugenda rwimuka kandi rwerekana imiterere yimitsi. Ubushyuhe bwikirahure (Tg) numutungo wingenzi wa amorphous polymers.
Ubushyuhe bwikirahure ni kimwe mubiranga ubushyuhe bwa polymers. Ufashe ubushyuhe bwikirahure nkurubibi, polymers yerekana ibintu bitandukanye bifatika: munsi yubushyuhe bwikirahure, ibikoresho bya polymer ni plastiki; hejuru yubushyuhe bwikirahure, ibikoresho bya polymer ni reberi. Urebye mubikorwa bya injeniyeri, imipaka yo hejuru yo gukoresha ubushyuhe bwikirahure cyubushyuhe bwubushyuhe bwa plastike ni ntarengwa yo gukoresha reberi cyangwa elastomers.
Igihe cyo kohereza: Mutarama-04-2024