Polyurethane: Tsvagiridzo pamusoro pekuoma kwepamusoro uye hunhu hwekuzviporesa hwePolyurethane Self-Healing Coatings zvichibva paDiels–Alder Reaction

Kuti vagadzirise nyaya yekuti machira epurasitiki echinyakare anogona kukuvara uye asina hunyanzvi hwekuzvirapa, vaongorori vakagadzira machira epurasitiki ekuzvirapa ane 5 wt% uye 10 wt% ekuporesa kuburikidza neDiels-Alder (DA) cycloaddition mechanism. Mhedzisiro yacho inoratidza kuti kuiswa kwemishonga inoporesa kunowedzera kuomarara kwepurasitiki ne3%–12% uye kunoita kuti kuporesa kukwenye kwe85.6%–93.6% mukati memaminitsi makumi matatu pa120 °C, zvichiwedzera hupenyu hwemachira. Chidzidzo ichi chinopa mhinduro itsva yekudzivirira pamusoro pezvinhu zveinjiniya.

Munyaya yezvinhu zveinjiniya, kugadziriswa kwekukuvadzwa kwemuchina muzvinhu zvekuputira kwave kuri dambudziko guru kwenguva refu. Kunyangwe machira epurasitiki echinyakare achiratidza kusimba kwakanaka uye kunamatira kwemamiriro ekunze, mashandiro awo ekudzivirira anoderera nekukurumidza kana mavanga kana kuputika kwaitika. Vachifemerwa nemaitiro ekuzviporesa ezvipenyu, masayendisiti akatanga kutsvaga zvinhu zvinozviporesa zvichibva pazvisungo zve covalent zvinoshanduka, neDiels-Alder (DA) reaction ichiwana kutariswa kukuru nekuda kwemamiriro ayo ekuita zvinyoro uye kugona kwayo kudzoka. Zvisinei, tsvakiridzo iripo yakatarisana zvakanyanya ne linear polyurethane systems, zvichisiya mukaha mukudzidza kwehunhu hwekuzviporesa mu cross-linked polyurethane powder coatings.

Kuti vakunde dambudziko iri rehunyanzvi, vaongorori vemuno vakashandisa nzira itsva yekurapa DA — furan-maleic anhydride uye furan-bismaleimide — mu hydroxylated polyester resin system, vachigadzira polyurethane powder coating ine hunhu hwakanaka hwekuzvirapa. Chidzidzo ichi chakashandisa ¹H NMR kusimbisa chimiro chemishonga inorapa, differential scanning calorimetry (DSC) kuratidza kuti DA/retro-DA reactions inogona kudzoserwa kumashure here, uye nanoindentation techniques pamwe chete ne surface profilometry kuti vaongorore zvine hunhu hwe mechanical uye hunhu hwepamusoro hwemachira.

Panyaya yehunyanzvi hwekuedza, timu yekutsvagisa yakatanga kugadzira mishonga yekurapa ine hydroxyl-containing DA ichishandisa nzira yematanho maviri. Mushure mezvo, upfu hwepolyurethane hune mishonga yekurapa ine 5 wt% uye 10 wt% yakagadzirwa kuburikidza nekunyunguduka, uye hwakaiswa pasimbi uchishandisa electrostatic spraying. Nekuenzanisa nemapoka ekutonga asina mishonga yekurapa, simba rekuwanda kwemishonga yekurapa pahunhu hwezvinhu rakaongororwa zvakarongeka.

1.Ongororo yeNMR Inosimbisa Chimiro Chemushonga Wekuporesa

1 H NMR spectra yakaratidza kuti amine-inserted furan-maleic anhydride (HA-1) yakaratidza hunhu hweDA ring peaks paδ = 3.07 ppm uye 5.78 ppm, nepo furan-bismaleimide adduct (HA-2) yakaratidza chiratidzo cheDA bond proton chakajairika paδ = 4.69 ppm, zvichisimbisa kubudirira kwekugadzirwa kwemishonga inoporesa.

2.DSC Inoratidza Hunhu Hunogona Kudzoserwa Mukupisa

Makori eDSC akaratidza kuti masampuru ane mishonga inoporesa akaratidza kukwirira kwe endothermic kweDA reaction pa75 °C uye kukwirira kwe retro-DA reaction kuri pakati pe110–160 °C. Nzvimbo yepamusoro yakawedzera nehuwandu hwakawanda hwemishonga inoporesa, zvichiratidza kugona kushandura kupisa zvakanaka.

3.Miedzo yeNanoindentation Inoratidza Kuvandudzwa kweKuoma

Kuongororwa kwe nanoindentation kwakaratidza kuti kuwedzerwa kwe5 wt% uye 10 wt% kuporesa kwakawedzera kuomarara kwe coating ne3% uye 12%, zvichiteerana. Kukosha kwekuomarara kwe0.227 GPa kwakaramba kuripo kunyangwe pakadzika kwe8500 nm, zvichibva pa network yakabatana yakaumbwa pakati pe kuporesa kurapa ne polyurethane matrix.

4.Kuongorora Maumbirwo Epamusoro

Kuongororwa kwekuomarara kwepamusoro kwakaratidza kuti machira epurasitiki akachena akaderedza kukosha kweRz ye substrate ne86%, nepo machira ane mishonga inoporesa akaratidza kuwedzera kushoma kwekuomarara nekuda kwekuvapo kwezvidimbu zvakakura. Mifananidzo yeFESEM inoratidza shanduko dzinooneka muchimiro chepamusoro chinokonzerwa nezvidimbu zvemishonga inoporesa.

5.Kubudirira muKushanda Kwekurapa Kwekukwenya

Kuongororwa kwe optical microscopy kwakaratidza kuti machira ane 10 wt% kuporesa, mushure mekupisa pa120 °C kwemaminitsi makumi matatu, akaratidza kudzikira kwehupamhi hwekukwenya kubva pa141 μm kusvika pa9 μm, zvichiita kuti kuporesa kushande ne93.6%. Kushanda uku kwakanyanya kupfuura kwakataurwa mumabhuku aripo e linear polyurethane systems.

Zvakaburitswa muNext Materials, chidzidzo ichi chinopa zvinhu zvitsva zvakawanda: Chekutanga, machira epolyurethane powder akagadzirwa neDA anobatanidza hunhu hwakanaka hwemuchina nekugona kuzvirapa, zvichiita kuti kuomarara kuwedzere kusvika ku12%. Chechipiri, kushandiswa kwetekinoroji yekupfapfaidza nemagetsi kunoita kuti zvinhu zvinoporesa zvipararire zvakaenzana mukati me network yakabatana, zvichikunda kusarongeka kwenzvimbo kwakajairika kwemaitiro echinyakare e microcapsule. Chinonyanya kukosha ndechekuti, machira aya anowana kushanda kwakanaka kwekuporesa patembiricha yakaderera (120 °C), zvichipa kushanda kwakanyanya mumaindasitiri zvichienzaniswa netembiricha yekuporesa ye145 °C yakataurwa mumabhuku aripo. Chidzidzo ichi hachingopi nzira itsva yekuwedzera hupenyu hwemachira einjiniya asiwo chinogadzira hurongwa hwedzidziso hwekugadzira mamorekuru emachira anoshanda kuburikidza nekuongorora kwayo kwehuwandu hwehukama hwe "healing agent concentration-performance". Kugadziriswa kwehuwandu hwehydroxyl mune zvinhu zvinoporesa uye chiyero cheuretdione cross-linkers kunotarisirwa kuwedzera miganhu yekushanda kwemachira ekuzvirapa.