Incazelo yezinga lokushisa lokushintsha kwengilazi
I-Glass-Transition Temperature(Tg), izinga lokushisa lapho i-polymer ishintsha khona ukusuka esimweni sokunwebeka ukuya esimweni esiyingilazi，Ibhekisela ekushintsheni kwezinga lokushisa le-amorphous polymer (kuhlanganise nengxenye engeyona icrystalline kupholymer ecwebezelayo) isuka esimweni esiyingilazi. esimweni sokunwebeka kakhulu noma ukusuka kwesilandelayo kuya kwesingaphambili. Izinga lokushisa eliphansi kakhulu lapho izingxenye ze-macromolecular zama-amorphous polymers zingahamba ngokukhululeka. Ivamise ukumelwa ngu-Tg. Iyahluka kuye ngendlela yokulinganisa nezimo.
Lesi yinkomba yokusebenza ebalulekile yama-polymers. Ngaphezu kwalokhu kushisa, i-polymer ibonisa ukunwebeka; ngaphansi kwalokhu kushisa, i-polymer ikhombisa ukuqina. Kufanele kucatshangelwe uma isetshenziswa njengamapulasitiki, irabha, imicu yokwenziwa, njll. Isibonelo, izinga lokushisa lokushintsha kwengilazi le-polyvinyl chloride lingu-80°C. Nokho, akuwona umkhawulo ophezulu wezinga lokushisa lokusebenza lomkhiqizo. Isibonelo, izinga lokushisa elisebenzayo lerabha kufanele libe ngaphezu kwezinga lokushisa lokuguqulwa kwengilazi, ngaphandle kwalokho lizolahlekelwa ukuqina kwalo okuphezulu.
Ngenxa yokuthi uhlobo lwe-polymer lusagcina imvelo yalo, i-emulsion nayo inezinga lokushisa lokushintsha kwengilazi, okuyinkomba yokuqina kwefilimu yokugqoka eyakhiwe yi-emulsion ye-polymer. I-emulsion enezinga lokushisa eliphezulu lokuguqulwa kwengilazi ine-coating enobulukhuni obuphezulu, i-gloss ephezulu, ukumelana namabala okuhle, futhi akulula ukuyingcolisa, nezinye izakhiwo zayo zemishini zingcono ngokufanayo. Kodwa-ke, izinga lokushisa lokushintsha kwengilazi kanye nezinga lokushisa elincane lokwakha ifilimu nakho kuphezulu, okuletha izinkinga ezithile zokusebenzisa emazingeni okushisa aphansi. Lokhu kuwukuphikisana, futhi lapho i-emulsion ye-polymer ifinyelela izinga lokushisa elithile lokuguqulwa kwengilazi, izakhiwo zayo eziningi zizoshintsha ngokubalulekile, ngakho-ke izinga lokushisa lokuguqulwa kwengilazi elifanele kufanele lilawulwe. Ngokuphathelene nodaka oluguquliwe lwe-polymer, izinga lokushisa lokuguqulwa kwengilazi liphakeme, amandla okucindezela odaka olushintshiwe aphakama. Ukwehla kwezinga lokushisa lokushintsha kwengilazi, kuba ngcono izinga lokushisa eliphansi lodaka olushintshiwe.
Incazelo yezinga lokushisa elincane elenza ifilimu
I-Minimum Film Forming Temperature ibalulekileinkomba yodaka olomile oluxubile
I-MFFT ibhekisela ekushiseni okuphansi lapho izinhlayiya ze-polymer ku-emulsion zikwazi ukuhamba okwanele ukuze zihlangane ndawonye ukuze zenze ifilimu eqhubekayo. Enkambweni ye-emulsion ye-polymer eyenza ifilimu yokugqoka eqhubekayo, izinhlayiya ze-polymer kumele zenze ilungiselelo elihlanganiswe eduze. Ngakho-ke, ngaphezu kokuhlakazeka okuhle kwe-emulsion, izimo zokwenza ifilimu eqhubekayo zihlanganisa nokuguqulwa kwezinhlayiya ze-polymer. Okusho ukuthi, lapho umfutho we-capillary wamanzi udala ukucindezela okukhulu phakathi kwezinhlayiya eziyindilinga, lapho izinhlayiya eziyindilinga zihlelwa ngokusondelana, ukwanda komfutho kuyanda.
Lapho izinhlayiya zihlangana nomunye nomunye, ukucindezela okukhiqizwa ukuguquguquka kwamanzi kuphoqa izinhlayiya ukuba zicindezelwe futhi zikhubazeke ukuze zihlangane ukuze zenze ifilimu yokugqoka. Ngokusobala, kuma-emulsions anama-ejenti aqinile, iningi lezinhlayiya ze-polymer ziyizinhlayiya ze-thermoplastic, izinga lokushisa eliphansi, ubulukhuni obukhulu futhi kuzoba nzima ukukhubazeka, ngakho-ke kunenkinga yokushisa okuncane okwenza ifilimu. Okungukuthi, ngaphansi kwezinga lokushisa elithile, ngemva kokuba amanzi e-emulsion ehwamuka, izinhlayiya ze-polymer zisesesimweni esicacile futhi azikwazi ukuhlanganiswa. Ngakho-ke, i-emulsion ayikwazi ukwakha ukugqoka okufanayo okufanayo ngenxa yokuhwamuka kwamanzi; futhi Ngaphezu kwaleli zinga lokushisa elithile, lapho amanzi ehwamuka, ama-molecule ezinhlayiya ze-polymer ngayinye azongena, ahlakazeke, akhubazeke, futhi ahlangane ukuze akhe ifilimu esobala eqhubekayo. Lo mkhawulo ophansi wezinga lokushisa lapho ifilimu ingakhiwa khona ubizwa ngokuthi izinga lokushisa elincane lokwakheka kwefilimu.
I-MFFT iyinkomba ebalulekile yei-emulsion ye-polymer, futhi kubaluleke kakhulu ukusebenzisa i-emulsion phakathi nezinkathi zokushisa eziphansi. Ukuthatha izinyathelo ezifanele kungenza i-emulsion ye-polymer ibe nesilinganiso esincane sokushisa sokwenza ifilimu esihlangabezana nezidingo zokusetshenziswa. Isibonelo, ukwengeza i-plasticizer ku-emulsion kungathambisa i-polymer futhi kunciphise kakhulu izinga lokushisa elincane lefilimu le-emulsion, noma ulungise izinga lokushisa elincane lefilimu. Ama-emulsions e-polymer aphezulu asebenzisa izithasiselo, njll.
I-MFFT yaseLongouImpushana ye-latex ehlakazeka kabusha ye-VAEngokuvamile iphakathi kuka-0°C no-10°C, evame kakhulu ngu-5°C. Kuleli zinga lokushisa, ii-polymer powderyethula ifilimu eqhubekayo. Ngokuphambene nalokho, ngaphansi kwalokhu kushisa, ifilimu ye-polymer powder e-redispersible ayisaqhubeki futhi iphuka.Ngakho-ke, izinga lokushisa elincane lokwakha ifilimu liyinkomba emele izinga lokushisa lokwakhiwa kwephrojekthi. Ngokuvamile, ukwehlisa izinga lokushisa elincane lokwakhiwa kwefilimu, kuba ngcono ukusebenza.
Umehluko phakathi kwe-Tg ne-MFFT
1. Izinga lokushisa lokushintsha kwengilazi, izinga lokushisa okuthambisa ngalo into ethile. Ikakhulukazi ibhekisela ezingeni lokushisa lapho ama-polymer amorphous aqala ukuthamba. Ayihlobene kuphela nesakhiwo se-polymer, kodwa futhi nesisindo sayo samangqamuzana.
2.Iphuzu lokuthambisa
Ngokwamandla okunyakaza ahlukene wamapholymeri, izinto eziningi ze-polymer ngokuvamile zingaba sezimo ezine ezilandelayo (noma izimo zokusebenza): isimo sengilazi, isimo se-viscoelastic, isimo esinwebeka kakhulu (isimo serabha) kanye nesimo sokugeleza kwe-viscous. Uguquko lwengilazi luwushintsho phakathi kwesimo esinwebeka kakhulu nesimo esiyingilazi. Kusukela kumbono wesakhiwo samangqamuzana, izinga lokushisa lokushintsha kwengilazi liyinto yokunethezeka yengxenye ye-amorphous ye-polymer ukusuka kusimo esiyiqhwa ukuya endaweni encibilikisiwe, ngokungafani nesigaba. Kunokushisa koshintsho lwesigaba phakathi noshintsho, ngakho-ke ukuguqulwa kwesigaba sesibili (okubizwa ngokuthi ukuguqulwa okuyinhloko kumakhenikha we-polymer dynamic). Ngaphansi kwezinga lokushisa lokushintsha kwengilazi, i-polymer isesimweni sengilazi, futhi amaketanga amangqamuzana namasegimenti awakwazi ukunyakaza. Ama-athomu kuphela (noma amaqembu) akha ama-molecule adlidlizayo lapho emile khona; ngenkathi ekushiseni kwenguquko yengilazi, nakuba amaketanga amangqamuzana Akwazi ukunyakaza, kodwa izingxenye zamaketanga ziqala ukunyakaza, zibonisa izakhiwo eziphakeme zokunwebeka. Uma izinga lokushisa likhuphuka futhi, lonke iketango lamangqamuzana lizohamba futhi libonise izakhiwo zokugeleza kwe-viscous. Izinga lokushisa le-Glass Transition (Tg) liyimpahla ebalulekile yama-amorphous polymers.
Izinga lokushisa lokushintsha kwengilazi lingelinye lamazinga okushisa e-polymers. Ukuthatha izinga lokushisa lokuguqulwa kwengilazi njengomngcele, ama-polymers abonisa izakhiwo ezihlukene zomzimba: ngaphansi kwezinga lokushisa lokushintsha kwengilazi, impahla ye-polymer iyipulasitiki; ngaphezu kwezinga lokushisa lokuguqulwa kwengilazi, impahla ye-polymer iyirabha. Ngokombono wezinhlelo zokusebenza zobunjiniyela, umkhawulo ongaphezulu wokusetshenziswa kwezinga lokushisa kwengilazi yokuguqula izinga lokushisa lamapulasitiki obunjiniyela ngumkhawulo ophansi wokusetshenziswa kwerabha noma ama-elastomers.
Isikhathi sokuthumela: Jan-04-2024