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Stearic acid (SA) inoshandiswa sechinhu chinochinja-chinja chikamu (PCM) mumidziyo yekuchengetera simba. Muchidzidzo ichi, nzira ye sol-gel yakashandiswa kuisa microcapsulate SiO2 shell surfactant. Huwandu hwakasiyana hweSA (5, 10, 15, 20, 30, uye 50 g) hwakaiswa mu10 mL ye tetraethyl orthosilicate (TEOS). Chinhu chinogadziriswa microencapsulated phase change material (MEPCM) chaive neFourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), uye scanning electron microscopy (SEM). Mhedzisiro yehunhu yakaratidza kuti SA yakaiswa zvinobudirira neSiO2. Thermogravimetric analysis (TGA) yakaratidza kuti MEPCM ine kugadzikana kuri nani kwekupisa kupfuura CA. Uchishandisa differential scanning calorimetry (DSC), zvakaonekwa kuti enthalpy value yeMEPCM haina kuchinja kunyangwe mushure memakumi matatu ekupisa-kutonhodza. Pakati pemasampuli ese akavharirwa muzvikamu zvidiki, 50 g yeSA ine MEPCM yaive nekupisa kwakanyanya kwekunyunguduka nekusimba, izvo zvaive 182.53 J/g uye 160.12 J/g, zvichiteerana. Kukosha kwekushanda kwepakeji kwakaverengerwa uchishandisa data rekupisa uye kushanda kwepamusoro kwakawanikwa kwemuenzaniso mumwe chete uyo waiva 86.68%.
Inenge 58% yesimba rinoshandiswa muindasitiri yekuvaka rinoshandiswa kupisa nekutonhodza zvivakwa1. Saka, chinhu chinonyanya kukosha kugadzira masisitimu esimba anoshanda anofunga nezvekusvibiswa kwezvakatipoteredza2. Tekinoroji yekupisa yakavanzika inoshandisa zvinhu zvekuchinja chikamu (PCM) inogona kuchengetedza simba rakawanda pakuchinja kwetembiricha kwakaderera3,4,5,6 uye inogona kushandiswa zvakanyanya munzvimbo dzakadai sekuchinjisa kupisa, kuchengetedza simba rezuva, aerospace uye air conditioning7,8,9. PCM inotora simba rekupisa kubva kunze kwezvivakwa masikati uye inoburitsa simba husiku10. Naizvozvo, zvinhu zvekuchinja chikamu zvinokurudzirwa sezvinhu zvekuchengetedza simba rekupisa. Pamusoro pezvo, kune mhando dzakasiyana dzePCM dzakadai sesolid-solid, solid-liquid, liquid-gas uye solid-gas11. Pakati padzo, zvinhu zvekuchinja chikamu zvinonyanya kufarirwa uye zvinoshandiswa kazhinji zvinhu zvekuchinja chikamu zvine solid-solid phase change zvinhu uye solid-liquid phase change zvinhu. Zvisinei, kushandiswa kwazvo kwakaoma nekuda kwekuchinja kukuru kwevolumetric kwezvinhu zvekuchinja chikamu zvine liquid-gas uye solid-gas phase.
PCM ine mashandisirwo akasiyana-siyana nekuda kwehunhu hwayo: ayo anonyunguduka patembiricha iri pasi pe15°C anogona kushandiswa mumhepo inotonhorera kuchengetedza tembiricha inotonhora, uye ayo anonyunguduka patembiricha iri pamusoro pe90°C anogona kushandiswa mumhepo inodziya kudzivirira moto12. Zvichienderana nekushandiswa uye nzvimbo yekunyunguduka, zvinhu zvakasiyana-siyana zvekuchinja kwechikamu zvakagadzirwa kubva kumakemikari akasiyana-siyana eorganic neasina organic13,14,15. Paraffin ndiyo inonyanya kushandiswa pakuchinja kwechikamu ine kupisa kwakanyanya, isingaparadzi, yakachengeteka uye nzvimbo yakafara yekunyunguduka16,17,18,19,20,21.
Zvisinei, nekuda kwekudzikira kwekupisa kwezvinhu zvinochinja chikamu, zvinoda kuvharwa mugoko (chikamu chekunze) kudzivirira kubuda kwechinhu chepasi panguva yekuchinja chikamu22. Pamusoro pezvo, zvikanganiso zvekushanda kana kumanikidzwa kwekunze zvinogona kukuvadza chikamu chekunze (cladding), uye chinhu chinochinja chikamu chakanyungudutswa chinogona kusangana nezvinhu zvekuvaka, zvichikonzera ngura yesimbi yakapinzwa, nokudaro zvichideredza kushanda kwechivako23. Saka, zvakakosha kugadzira zvinhu zvinochinja chikamu zvakapinzwa nezvinhu zvakakwana zvegoko, izvo zvinogona kugadzirisa matambudziko ari pamusoro apa24.
Kupinza zvinhu muchikamu chekuchinja kwechikamu (phase change materials) kunogona kuwedzera kupisa uye kuderedza reactivity yezvakatipoteredza, uye kudzora kuchinja kwehuwandu hwezvinhu. Nzira dzakasiyana-siyana dzakagadzirwa dzePCM encapsulation, dzinoti interfacial polymerization25,26,27,28, in situ polymerization29,30,31,32, coacervation33,34,35 uye sol-gel processes36,37,38,39. Formaldehyde resin inogona kushandiswa kune microencapsulation40,41,42,43. Melamine-formaldehyde uye urea-formaldehyde resins zvinoshandiswa sezvinhu zveganda, izvo zvinowanzoburitsa formaldehyde ine chepfu panguva yekushanda. Nokudaro, zvinhu izvi hazvibvumirwi kushandiswa muzvirongwa zvekurongedza. Zvisinei, zvinhu zvekuchinja zvikamu zvine hushamwari kune zvakatipoteredza zvekuchengetera simba rekupisa zvinogona kugadzirwa uchishandisa hybrid nanocapsules zvichibva pamafuta acids uye lignin 44.
Zhang nevamwe 45 vakagadzira lauric acid kubva ku tetraethyl orthosilicate uye vakagumisa kuti sezvo huwandu hwemethyltriethoxysilane kuenda ku tetraethyl orthosilicate huchiwedzera, kupisa kwakavanzika kunoderera uye hydrophobicity yepamusoro inowedzera. Lauric acid inogona kunge iri chinhu chakakosha uye chinoshanda che kapok fibers46. Pamusoro pezvo, Latibari nevamwe 47 vakagadzira stearic acid-based PCMs vachishandisa TiO2 sechinhu cheganda. Zhu nevamwe vakagadzira n-octadecane uye silicone nanocapsules sePCMs dzinogona kushanda 48. Kubva pakuongorora zvinyorwa, zvakaoma kunzwisisa chiyero chinokurudzirwa chekugadzira zvinhu zvinoshanda uye zvakagadzikana zve microencapsulated phase change.
Saka, sekuziva kwevanyori, huwandu hwezvinhu zvinoshandiswa pakuchinja chikamu (phase change) chinhu chakakosha pakugadzira zvinhu zvinobudirira uye zvakagadzikana zvekuchinja chikamu (microencapsulated phase change). Kushandisa huwandu hwakasiyana hwezvinhu zvinochinja chikamu (phase change) kuchatibvumira kujekesa hunhu hwakasiyana uye kugadzikana kwezvinhu zvinochinja chikamu (phase change). Stearic acid (fatty acid) chinhu chine hushamwari kune nharaunda, chakakosha pakurapa uye chinodhura chinogona kushandiswa kuchengetedza simba rekupisa nekuti chine enthalpy yakakosha (~200 J/g) uye chinogona kutsungirira tembiricha inosvika 72 °C. Pamusoro pezvo, SiO2 haibati, inopa simba repamusoro remuchina, thermal conductivity uye makemikari ari nani kupokana nezvinhu zvepakati, uye inoshanda sechinhu chinodzivirira mukuvaka. Kana simende ikasanganiswa nemvura, maPCM asina kuputirwa zvakanaka anogona kutsemuka nekuda kwekusakara kwemuchina uye tembiricha yakakwira (kupisa kwemvura) inogadzirwa muzvivakwa zvikuru zvekongiri. Nokudaro, kushandiswa kweCA ine SiO2 shell kunogona kugadzirisa dambudziko iri. Saka, chinangwa chechidzidzo ichi chaive chekuongorora mashandiro uye kushanda zvakanaka kwePCMs dzinogadzirwa nemaitiro e sol-gel mukuvaka. Mubasa iri, takadzidza zvakarongeka huwandu hwakasiyana hweSA (sezvinhu zvekutanga) hwe5, 10, 15, 20, 30 uye 50 g dzakaputirwa mumagoko eSiO2. Huwandu hwakatarwa hwetetraethylorthosilicate (TEOS) muhuwandu hwe10 ml hwakashandiswa senzira yekutanga kuumbwa kwegoko reSiO2.
Reactive grade stearic acid (SA, C18H36O2, melting point: 72°C) sezvinhu zvepakati zvakatengwa kubva kuDaejung Chemical & Metals Co., Ltd., Gyeonggi-do, South Korea. Tetraethylorthosilicate (TEOS, C8H20O4Si) semushonga wekutanga yakatengwa kubva kuAcros Organics, Geel, Belgium. Pamusoro pezvo, absolute ethanol (EA, C2H5OH) uye sodium lauryl sulfate (SLS, C12H25NaO4S) zvakatengwa kubva kuDaejung Chemical & Metals Co., Ltd, Gyeonggi-do, South Korea, uye zvakashandiswa se solvents uye surfactants, zvichiteerana. Mvura yakasanganiswa inoshandiswawo se solvent.
Huwandu hwakasiyana hweSA hwakasanganiswa nehuwandu hwakasiyana hwesodium lauryl sulfate (SLS) mu 100 mL yemvura yakasanganiswa uchishandisa magnetic stirrer pa 800 rpm uye 75 °C kweawa imwe (Tafura 1). SA emulsions dzakakamurwa kuita mapoka maviri: (1) 5, 10 uye 15 g yeSA yakasanganiswa ne 0.10 g yeSLS mu 100 ml yemvura yakasanganiswa (SATEOS1, SATEOS2 uye SATEOS3), (2) 20, 30 uye 50 g yeSA yakasanganiswa ne 0.15, 0.20 uye 0.25 g yeSLS yakasanganiswa ne 100 ml yemvura yakasanganiswa (SATEOS4, SATEOS5 uye SATEOS6). 0.10 g SLS yakashandiswa ne 5, 10 uye 15 g SA kugadzira emulsions dzakabatana. Mushure mezvo, zvakakurudzirwa kuwedzera huwandu hweSLS yeSATEOS4, SATEOS5 uye SATEOS6. Tafura 1 inoratidza zviyero zveCA neSLS zvinoshandiswa kuwana mhinduro dzakagadzikana dze emulsion.
Isa 10 ml TEOS, 10 ml ethanol (EA) uye 20 ml mvura yakasanganiswa mubeaker ye100 ml. Kuti udzidze kushanda kwe encapsulation kwezvikamu zvakasiyana zveSA neSiO2 shells, synthesis coefficient yesampuli dzese yakanyorwa. Musanganiswa wacho wakakurungwa ne magnetic stirrer pa400 rpm uye 60°C kweawa imwe chete. Precursor solution yakazowedzerwa dropwise kuSA emulsion yakagadzirwa, yakakurungwa nesimba pa800 rpm uye 75 °C kwemaawa maviri, uye yakasefetwa kuti pave nehupfu huchena. Hupfu huchena hwakagezwa nemvura yakasanganiswa kuti hubvise SA yakasara uye hwakaomeswa mu vacuum oven pa45°C kwemaawa makumi maviri nemana. Nekuda kweizvozvo, microencapsulated SC ine ganda reSiO2 yakawanikwa. Maitiro ese ekugadzira nekugadzirira microencapsulated SA anoratidzwa muMufananidzo 1.
Ma microcapsule eSA ane ganda reSiO2 akagadzirwa nenzira ye sol-gel, uye nzira yavo yekuvhara inoratidzwa muMufananidzo 2. Danho rekutanga rinosanganisira kugadzirira emulsion yeSA mumvura ine SLS se surfactant. Muchiitiko ichi, mugumo we hydrophobic weSA molecule unosunga kuSLS, uye mugumo we hydrophilic kumamorekuru emvura, zvichigadzira emulsion yakagadzikana. Saka, zvikamu zve hydrophobic zveSLS zvinodzivirirwa uye zvinofukidza pamusoro pedonhwe reSA. Kune rumwe rutivi, hydrolysis yemhinduro dzeTEOS inoitika zvishoma nezvishoma nemamorekuru emvura, zvichikonzera kuumbwa kwe hydrolyzed TEOS pamberi pe ethanol (Mufananidzo 2a) 49,50,51. Hydrolyzed TEOS inosangana ne condensation reaction, panguva iyo n-hydrolyzed TEOS inoumba silica clusters (Mufananidzo 2b). Silica clusters dzakavharirwa neSA52 pamberi peSLS (Mufananidzo 2c), iyo inonzi microencapsulation process.
Dhiyagiramu yemufananidzo we microencapsulation yeCA negoko reSiO2 (a) hydrolysis yeTEOS (b) condensation ye hydrolyzate uye (c) encapsulation yeCA negoko reSiO2.
Kuongororwa kwemakemikari kwe bulk SA ne microencapsulated SA kwakaitwa uchishandisa Fourier transform infrared spectrometer (FT-IR, Perkin Elmer UATR Two, USA) uye ma spectra akanyorwa ari pakati pe500 kusvika 4000 cm-1.
Chiyero cheX-ray diffractometer (XRD, D/MAX-2500, Rigaku, Japan) chakashandiswa kuongorora bulk SA phases nezvinhu zve microcapsule. X-ray structural scanning yakaitwa munzvimbo iri pakati pe2θ = 5°–95° nekumhanya kwekuskena kwe4°/min, uchishandisa Cu-Kα radiation (λ = 1.541 Å), mamiriro ekushanda e25 kV uye 100 mA, mu continuous scanning mode. Mifananidzo yeX-ray yakagadzirwa munzvimbo iri pakati pe2θ = 5–50°, sezvo pasina peak yakaonekwa mushure me50° musampuli dzese.
X-ray photoelectron spectroscopy (XPS, Scienta Omicron R3000, USA) yakaitwa uchishandisa Al Kα (1486.6 eV) senzvimbo yeX-ray kunzwisisa mamiriro emakemikari e bulk SA pamwe nezvinhu zviri mu encapsulation material. XPS spectra dzakaunganidzwa dzakagadziriswa kusvika pa C 1s peak uchishandisa exotic carbon (binding energy 284.6 eV). Mushure mekugadziriswa kwemashure uchishandisa Shirley method, high-resolution peaks yechinhu chimwe nechimwe yakabviswa convolution ndokuiswa kumabasa eGaussian/Lorentzian uchishandisa CASA XPS software.
Maumbirwo eSc yakawanda neSC yakavharirwa muzvikamu zvidiki akaongororwa pachishandiswa scanning electron microscopy (SEM, MIRA3, TESCAN, Brno, Czech Republic) yakashongedzerwa ne energy-dispersive X-ray spectroscopy (EDS) pa15 kV. SEM isati yatorwa mifananidzo, sampuro dzaizora platinum (Pt) kudzivirira kushaikwa kwesimba.
Hunhu hwekupisa (nzvimbo yekunyunguduka/kusimba uye kupisa kwakavanzika) uye kuvimbika (thermal cycling) zvakaongororwa ne differential scanning calorimetry (DSC, TA Instrument, Discovery DSC, Newcastle, USA) pachiyero chekupisa/kutonhodza che10 °C/min pa40 °C. uye 90 °C ne continuous nitrogen purge. Kuongorora kuderedza uremu kwakaitwa uchishandisa TGA analyzer (TA Instrument, Discovery TGA, New Castle, USA) mukuyerera kwenitrogen kunoramba kuripo kutanga patembiricha ye40–600 °C, nechiyero chekupisa che10 °C/min.
Mufananidzo 3 unoratidza ma FTIR spectra e SC yakawanda pamwe ne microencapsulated SC (SATEOS1, SATEOS2, SATEOS3, SATEOS4, SATEOS5 naSATEOS6). Kukwira kwemvura pa 2910 cm-1 uye 2850 cm-1 muzviyero zvese (SA pamwe ne microencapsulated SA) kunokonzerwa nekutenderera kwe symmetrical stretching vibrations ye –CH3 ne –CH2 groups, zvichiteerana10,50. Kukwira kwemvura pa 1705 cm-1 kunoenderana nekutenderera kwe vibrational kweC=O bond. Kukwira kwemvura pa 1470 cm-1 uye 1295 cm-1 kunokonzerwa nekutenderera kwe in-plane bend kwe –OH functional group, nepo kukwira kwemvura pa 940 cm-1 uye 719 cm-1 kunoenderana nekutenderera kwe in-plane uye yield. -plane deformation vibration, zvichiteerana - OH group. Kunyudzwa kweSA pa2910, 2850, 1705, 1470, 1295, 940 uye 719 cm-1 kwakaonekwawo muSA yese ine microcapsulated. Pamusoro pezvo, peak ichangobva kuwanikwa pa1103 cm-1 inoenderana nekudengenyeka kwekutambanudza kweSi-O-Si band kwakaonekwa muSA microcapsule. Mhedzisiro yeFT-IR inoenderana naYuan et al. 50 Vakagadzira SA ine microcapsulated muhuwandu hweammonia/ethanol uye vakaona kuti hapana kusangana kwemakemikari kwakaitika pakati peSA neSiO2. Mhedzisiro yechidzidzo cheFT-IR chiripo inoratidza kuti ganda reSiO2 rakanyatso putirwa SA (core) kuburikidza nemaitiro ekunyorovesa uye polymerization yeTEOS ine hydrolyzed. PaSA yakaderera, simba repamusoro reSi-O-Si band rakakwira (Mufananidzo 3b-d). Sezvo huwandu hweSA huchiwedzera kusvika pa15 g, simba repamusoro uye kuwedzera kweSi-O-Si band kunoderera zvishoma nezvishoma, zvichiratidza kuumbwa kwechikamu chakatetepa cheSiO2 pamusoro peSA.
Mifananidzo yeFTIR ye (a) SA, (b) SATEOS1, (c) SATEOS2, (d) SATEOS3, (e) SATEOS4, (f) SATEOS5 uye (g) SATEOS6.
Mapatani eXRD e bulk SA ne microencapsulated SA anoratidzwa muMufananidzo 4. Ma XRD peaks ari pa2θ = 6.50° (300), 10.94° (500), 15.46° (700), 20.26° \((\overline {5}maererano neJCPDS Nhamba 0381923, 02)\), 21.42° musampuli dzese (311), 24.04° (602) uye 39.98° (913) anopiwa kuSA. Kukanganiswa uye kusanganiswa ne bulk CA nekuda kwezvinhu zvisina chokwadi zvakaita se surfactant (SLS), zvimwe zvinhu zvakasara uye microencapsulation yeSiO250. Mushure mekunge encapsulation yaitika, simba re main peaks (300), (500), (311), uye (602) rinoderera zvishoma nezvishoma zvichienzaniswa ne bulk CA, zvichiratidza kudzikira kwekristaro yesample.
Mapatani eXRD e (a) SA, (b) SATEOS1, (c) SATEOS2, (d) SATEOS3, (e) SATEOS4, (f) SATEOS5 uye (g) SATEOS6.
Simba reSATEOS1 rinoderera zvakanyanya kana tichienzanisa nedzimwe sampuro. Hapana mamwe mapeaks akaonekwa musampuli dzese dzakaiswa muzvikamu zvidiki (Mufananidzo 4b–g), izvo zvinosimbisa kuti kunyudzwa kweSiO252 panzvimbo pekudyidzana kwemakemikari kunoitika pamusoro peSA. Pamusoro pezvo, zvakagumiswawo kuti microencapsulation yeSA haina kutungamira pakuonekwa kwezvimiro zvitsva. SiO2 inoramba isina chinhu pamusoro peSA pasina chero reaction yemakemikari, uye sezvo huwandu hweSA huchiderera, mapeaks aripo anova pachena (SATEOS1). Mhedzisiro iyi inoratidza kuti SiO2 inonyanya kufukidza pamusoro peSA. Mapeaks pa (700) anonyangarika zvachose, uye mapeaks pa \((\overline{5}02)\) anova hump muSATEOS 1 (Mufananidzo 4b), iyo inobatanidzwa nekudzikira kwekristaro uye kuwedzera kweamorphism. SiO2 haina chimiro chakafanana, saka misoro inoonekwa kubva pa2θ = 19° kusvika 25° ine hump uye broadening53 (Mufananidzo 4b–g), izvo zvinosimbisa kuvapo kweSiO252 isina chimiro. Kusimba kwepasi kwe diffraction peak ye microencapsulated SA kunokonzerwa ne nucleation effect ye silica inner wall uye limitation crystallization behavior49. Zvinotendwa kuti neSA content yakaderera, silica shell yakakora inoumbwa nekuda kwekuvapo kwehuwandu hwakawanda hweTEOS, iyo inonyanya kunamirwa pamusoro pekunze kweSA. Zvisinei, sezvo huwandu hweSA huchiwedzera, nzvimbo yepamusoro yemadonhwe eSA mu emulsion solution inowedzera uye TEOS yakawanda inodiwa kuti ive yakavharidzirwa zvakanaka. Nokudaro, neSA content yakakwira, SiO2 peak muFT-IR inodzvinyirirwa (Mufananidzo 3), uye simba re diffraction peak pedyo ne2θ = 19–25° muXRF (Mufananidzo 4) inoderera uye kuwedzera kunodererawo. Hazvionekwe. Zvisinei, sezvinoonekwa muMufananidzo 4, kana huwandu hweSA hwangowedzerwa kubva pa5 g (SATEOS1) kusvika pa50 g (SATEOS6), misoro inoswedera pedyo nebulk SA, uye peak pa (700) inoonekwa nekuwanda kwese kwepeak kwakaonekwa. Mhedzisiro iyi inoenderana neFT-IR results, uko simba reSiO2 SATEOS6 peak rinoderera pa1103 cm-1 (Mufananidzo 3g).
Mamiriro emakemikari ezvinhu aripo muSA, SATEOS1 neSATEOS6 anoratidzwa muMifananidzo 1 ne2. Mifananidzo 5, 6, 7 ne8 neTafura 2. Kuyerwa kwekuongorora kwehuwandu hweSA, SATEOS1 neSATEOS6 kunoratidzwa muMufananidzo 5 uye kuyera kwepamusoro kweC 1s, O 1s neSi 2p kunoratidzwa muMifananidzo 5, 6, 7 ne8 neTafura 2. 6, 7 ne8 zvichiteerana. Simba rekubatanidza rakawanikwa neXPS rakapfupikiswa muTafura 2. Sezvatinoona kubva kuMufananidzo 5, Si 2s neSi 2p peaks dzakaonekwa muSATEOS1 neSATEOS6, uko kwakaitika microencapsulation yeSiO2 shell. Vaongorori vekare vakataura nezveSi 2s peak yakafanana pa155.1 eV54. Kuvapo kweSi peaks muSATEOS1 (Mufananidzo 5b) neSATEOS6 (Mufananidzo 5c) kunosimbisa data reFT-IR (Mufananidzo 3) neXRD (Mufananidzo 4).
Sezvakaratidzwa muMufananidzo 6 a, maC1 ehuwandu hweSA ane mativi matatu akasiyana eCC, caliphatic, uye O=C=O pasimba rekubatanidza, ayo ari 284.5 eV, 285.2 eV, uye 289.5 eV, zvichiteerana. Mapoka eC–C, caliphatic uye O=C=O akaonekwawo muSATEOS1 (Mufananidzo 6b) uye SATEOS6 (Mufananidzo 6c) uye akapfupikiswa muTafura 2. Pamusoro peizvi, peak yeC1s inoenderanawo neSi-C peak yakawedzerwa pa283 .1 eV (SATEOS1) uye 283.5 eV (SATEOS6). Simba redu rekubatanidza rakaonekwa reC–C, caliphatic, O=C=O uye Si–C rinoenderana zvakanaka nemamwe masosi55,56.
MaXPS spectra eO1 SA, SATEOS1 naSATEOS6 anoratidzwa muMifananidzo 7a–c, zvichiteerana. O1s peak ye bulk SA yakabviswa convoluted uye ine peaks mbiri, dzinoti C=O/C–O (531.9 eV) uye C–O–H (533.0 eV), nepo O1 yeSATEOS1 naSATEOS6 dzichienderana. kune peaks nhatu chete: C=O/C–O, C–O–H naSi–OH55,57,58. Simba rekubatanidza O1s muSATEOS1 naSATEOS6 rinoshanduka zvishoma zvichienzaniswa ne bulk SA, iyo inobatanidzwa nekuchinja kwechikamu chemakemikari nekuda kwekuvapo kweSiO2 neSi-OH muzvinhu zveganda.
MaSi 2p XPS spectra eSATEOS1 neSATEOS6 anoratidzwa muMufananidzo 8a neb, zvichiteerana. Muhuwandu hweCA, Si 2p haina kuonekwa nekuda kwekushaikwa kweSiO2. Si 2p peak inoenderana ne105.4 eV yeSATEOS1 ne105.0 eV yeSATEOS6, inoenderana neSi-O-Si, nepo SATEOS1 peak iri 103.5 eV uye SATEOS6 peak iri 103.3 eV, inoenderana neSi-OH55. Si-O-Si neSi-OH peak fitting muSATEOS1 neSATEOS6 zvakaratidza kubudirira kwe microencapsulation yeSiO2 pamusoro peSA core surface.
Maumbirwo echinhu chakavharirwa muzvikamu zvidiki akakosha zvikuru, achikanganisa kunyungudika, kugadzikana, reactivity yemakemikari, kufamba zvakanaka uye simba59. Nokudaro, SEM yakashandiswa kuratidza maumbirwo ehuwandu hweSA (100×) uye SA (500×), sezvakaratidzwa muMufananidzo 9. Sezvatinoona muMufananidzo 9a, SA block ine chimiro cheelliptical. Saizi yezvikamu inodarika 500 microns. Zvisinei, kana maitiro e microencapsulation aramba achienderera mberi, maumbirwo acho anochinja zvakanyanya, sezvakaratidzwa muMifananidzo 9 b–g.
Mifananidzo yeSEM ​​ye (a) SA (×100), (b) SATEOS1, (c) SATEOS2, (d) SATEOS3, (e) SATEOS4, (f) SATEOS5 uye (g) SATEOS6 pa ×500.
Mumuenzaniso weSATEOS1, zvidimbu zvidiki zveSA zvakaputirwa neSiO2-zvakaputirwa zvine nzvimbo isina kurongeka zvinoonekwa (Mufananidzo 9b), izvo zvinogona kunge zvichikonzerwa nekunyungudika kweTEOS uye kuumbwa kwemvura inoyerera pamusoro peSA, zvichikurumidzisa kupararira nekukurumidza kwemamorekuru eethanol. Nekuda kweizvozvo, zvidimbu zveSiO2 zvinoiswa uye agglomeration inoonekwa52,60. Goko iri reSiO2 rinopa simba remakanika kune zvidimbu zveCA zvakavharirwa uye rinodzivirirawo kubuda kweCA yakanyungudutswa pakupisa kwakanyanya10. Mhedzisiro iyi inoratidza kuti zvidimbu zveSA zvine SiO2 zvinogona kushandiswa sezvinhu zvinogona kuchengetwa simba61. Sezvazvinogona kuonekwa kubva kuMufananidzo 9b, sampuli yeSATEOS1 ine kugoverwa kwezvikamu zvakafanana neSiO2 layer yakakora inofukidza SA. Saizi yezvikamu zveSA yakavharirwa (SATEOS1) inenge 10–20 μm (Mufananidzo 9b), iyo idiki zvikuru kana tichienzanisa neSA yakawanda nekuda kwehuwandu hwakaderera hweSA. Ukobvu hwe microcapsule layer hunokonzerwa ne hydrolysis uye condensation polymerization ye precursor solution. Agglomeration inoitika pa doses shoma dzeSA, kureva kusvika 15 g (Mufananidzo 9b-d), asi kana dose yawedzerwa, hapana agglomeration inoonekwa, asi zvidimbu zve spherical zvinoonekwa zvakajeka (Mufananidzo 9e-g) 62.
Pamusoro pezvo, kana huwandu hweSLS surfactant huchigara huripo, huwandu hweSA (SATEOS1, SATEOS2 naSATEOS3) hunokanganisawo kushanda zvakanaka, chimiro uye kugoverwa kwehukuru hwezvikamu. Saka, SATEOS1 yakawanikwa iine saizi diki yezvikamu, kugoverwa kwakafanana uye nzvimbo yakakora (Mufananidzo 9b), iyo yaifungidzirwa kuti ine hunhu hweSA hunofadza mvura hunokurudzira nucleation yechipiri pasi pe surfactant inogara iripo63. Zvinotendwa kuti nekuwedzera huwandu hweSA kubva pa5 kusvika ku15 g (SATEOS1, SATEOS2 naSATEOS3) uye kushandisa huwandu hwesurfactant hunogara huripo, kureva 0.10 g SLS (Tafura 1), mupiro wechikamu chimwe nechimwe chemorekuru yesurfactant uchaderera, nokudaro zvichideredza saizi yezvikamu uye saizi yezvikamu. Kugoverwa kweSATEOS2 (Mufananidzo 9c) naSATEOS3 (Mufananidzo 9d) kwakasiyana nekugoverwa kweSATEOS 1 (Mufananidzo 9b).
Zvichienzaniswa neSATEOS1 (Mufananidzo 9b), SATEOS2 yakaratidza chimiro chakakora cheSA yakavharirwa uye saizi yezvikamu yakawedzera (Mufananidzo 9c). Izvi zvinokonzerwa nekubatana 49, izvo zvinoderedza mwero wekuvharika (Mufananidzo 2b). Sezvo huwandu hweSC huchiwedzera nekuwedzera kweSLS, microcapsules dzinoonekwa zvakajeka, sezvakaratidzwa muMufananidzo. kuti kuungana kunoitika sei. Pamusoro pezvo, Mifananidzo 9e-g inoratidza kuti zvikamu zvese zvakajeka muchimiro nehukuru. Zvave zvichizivikanwa kuti kana paine huwandu hwakawanda hweSA, huwandu hwakakodzera hwe silica oligomers hunogona kuwanikwa, zvichikonzera kuunganidzwa kwakakodzera uye kuvharwa uye nekudaro kuumbwa kwe microcapsules dzakatsanangurwa zvakanaka49. Kubva mumhedzisiro yeSEM, zviri pachena kuti SATEOS6 yakagadzira microcapsules dzinoenderana zvichienzaniswa nehuwandu hushoma hweSA.
Mhedzisiro ye energy dispersive X-ray spectroscopy (EDS) ye bulk SA ne microcapsule SA inoratidzwa muTafura 3. Sezvatinoona kubva patafura iyi, huwandu hweSi hunoderera zvishoma nezvishoma kubva paSATEOS1 (12.34%) kusvika paSATEOS6 (2.68%). Kuwedzera muSA. Saka, tinogona kutaura kuti kuwedzera kwehuwandu hweSA kunotungamira kudzikira kwekuiswa kweSiO2 pamusoro peSA. Hapana hunhu hwakafanana hwezviri mukati meC neO muTafura 3 nekuda kwe semi-quantitative analysis yeEDS51. Hunhu hweSi hwe microencapsulated SA hwakabatana nemigumisiro yeFT-IR, XRD neXPS.
Maitiro ekunyunguduka nekusimba kwe bulk SA pamwe ne microencapsulated SA ine SiO2 shell anoratidzwa muMifananidzo 1 ne 2. Anoratidzwa muMifananidzo 10 ne 11 zvichiteerana, uye data rekupisa rinoratidzwa muTafura 4. Kunyunguduka nekusimba kwe microencapsulated SA kwakawanikwa kwakasiyana. Sezvo huwandu hweSA huchiwedzera, tembiricha yekunyunguduka nekusimba inowedzera uye inosvika pahukuru hwe bulk SA. Mushure me SA microencapsulation, madziro e silica anowedzera tembiricha yekukristallisa, uye madziro awo anoshanda sepakati pekusimudzira kusiyana. Naizvozvo, sezvo huwandu hweSA huchiwedzera, kunyunguduka (Mufananidzo 10) uye kusimba (Mufananidzo 11) tembiricha dzinowedzerawo zvishoma nezvishoma49,51,64. Pakati pemasampuli ese e microencapsulated SA, SATEOS6 yakaratidza tembiricha yepamusoro yekunyunguduka nekusimba, ichiteverwa neSATEOS5, SATEOS4, SATEOS3, SATEOS2, uye SATEOS1.
SATEOS1 inoratidza nzvimbo yakaderera yekunyunguduka (68.97 °C) uye tembiricha yekusimba (60.60 °C), izvo zvinokonzerwa nehukuru hudiki hwezvimedu umo kufamba kwezvimedu zveSA mukati mema microcapsules kuri kudiki kwazvo uye ganda reSiO2 rinoumba denderedzwa gobvu uye nokudaro Core Material inoganhurira kutambanudza nekufamba49. Iyi fungidziro ine chekuita nemhedzisiro yeSEM, apo SATEOS1 yakaratidza saizi diki yezvimedu (Mufananidzo 9b), izvo zvinokonzerwa nekuti mamorekuru eSA akavharirwa munzvimbo diki kwazvo yema microcapsules. Musiyano mukunyunguduka nekusimba kwehuremu hukuru, pamwe chete nema microcapsule ese eSA ane ma shells eSiO2, uri pakati pe6.10–8.37 °C. Mhedzisiro iyi inoratidza kuti microencapsulated SA inogona kushandiswa sechinhu chinogona kuchengetedza simba nekuda kwekupisa kwakanaka kweSiO2 shell 65.
Sezvatinoona kubva paTafura 4, SATEOS6 ine enthalpy yakanyanya kupfuura dzose pakati pemaSC ese ane microcapsulated (Mufananidzo 9g) nekuda kwekuvharwa kwakakodzera kwakaonekwa neSEM. SA packing rate inogona kuverengerwa uchishandisa equation (1). (1) Nekuenzanisa data rekupisa rakavanzika reSA49 ine microcapsulated.
Kukosha kweR kunomiririra dhigirii rekuvharwa kwechinhu (%) cheSC yakavharwa, ΔHMEPCM, m inomiririra kupisa kwakavanzika kwekusanganiswa kweSC yakavharwa, uye ΔHPCM, m inomiririra kupisa kwakavanzika kwekusanganiswa kweSC. Pamusoro pezvo, kushanda zvakanaka pakurongedza (%) kunoverengerwa seimwe parameter yakakosha yehunyanzvi, sezvakaratidzwa muEquation (1). (2)49.
Kukosha kweE kunomiririra kushanda zvakanaka kweCA yakavharirwa muzvikamu zvidiki (%), ΔHMEPCM,s inomiririra kupisa kwakavanzika kwekuporesa kweCA yakavharirwa muzvikamu zvidiki (microcapsulated), uye ΔHPCM,s inomiririra kupisa kwakavanzika kwekuporesa kweCA.
Sezvakaratidzwa muTafura 4, mwero wekurongedza uye kushanda zvakanaka kweSATEOS1 i71.89% uye 67.68%, zvichiteerana, uye mwero wekurongedza uye kushanda zvakanaka kweSATEOS6 i90.86% uye 86.68%, zvichiteerana (Tafura 4). Muenzaniso weSATEOS6 unoratidza mwero wepamusoro wekuvharwa uye kushanda zvakanaka pakati pemaSA ese ane microcapsulated, zvichiratidza kugona kwayo kupisa kwakanyanya. Nokudaro, kuchinja kubva kune yakasimba kuenda kune mvura kunoda simba rakawanda. Pamusoro pezvo, mutsauko mukunyunguduka nekusimba kwekushisa kwemaSA ese microcapsules nebulk SA panguva yekutonhora unoratidza kuti silica shell inovharwa munzvimbo panguva yekugadzira microcapsule. Saka, mhedzisiro inoratidza kuti sezvo huwandu hweSC huchiwedzera, mwero wekuvharwa uye kushanda zvakanaka zvinowedzera zvishoma nezvishoma (Tafura 4).
Makomba eTGA e bulk SA ne microcapsule SA ane ganda reSiO2 (SATEOS1, SATEOS3 neSATEOS6) anoratidzwa muMufananidzo 12. Hunhu hwekugadzikana kwekupisa kwe bulk SA (SATEOS1, SATEOS3 neSATEOS6) hwakaenzaniswa nemasampuli akavharirwa. Zviri pachena kubva mugwara reTGA kuti kurasikirwa nehuremu kwe bulk SA pamwe ne microencapsulated SA kunoratidza kudzikira kwakapfava uye kudiki kubva pa40°C kusvika 190°C. Pakupisa uku, bulk SC haiparare nekupisa, nepo microencapsulated SC inoburitsa mvura yakavharirwa kunyangwe mushure mekuoma pa45°C kwemaawa makumi maviri nemana. Izvi zvakakonzera kudzikira kudiki kwehuremu,49 asi kupfuura kupisa uku zvinhu zvakatanga kuora. Pakuderera kweSA (kureva SATEOS1), mvura yakavharirwa yakakwira uye nekudaro kurasikirwa nehuremu kusvika ku190 °C kwakakwira (mukati muMufananidzo 12). Kana tembiricha yangokwira pamusoro pe190 °C, sampuro inotanga kurasikirwa nehuremu nekuda kwekuora. Bulk SA inotanga kuora pa190 °C uye 4% chete inosara pa260 °C, nepo SATEOS1, SATEOS3 naSATEOS6 zvichiramba 50%, 20% uye 12% patembiricha iyi, zvichiteerana. Mushure me300 °C, kurasikirwa nehuremu kwebulk SA kwaive 97.60%, nepo kurasikirwa nehuremu kweSATEOS1, SATEOS3, naSATEOS6 kwaive 54.20%, 82.40%, uye 90.30% zvichiteerana. Nekuwedzera kwehuwandu hweSA, huwandu hweSiO2 hunoderera (Tafura 3), uye kutetepa kweganda kunoonekwa muSEM (Mufananidzo 9). Saka, kurasikirwa nehuremu kweSA yakavharirwa muzvikamu zvishoma kwakaderera kana tichienzanisa neSA yakawanda, izvo zvinotsanangurwa nehunhu hwakanaka hwegoko reSiO2, iro rinokurudzira kuumbwa kweganda recarbonaceous silicate-carbonaceous pamusoro peSA, nokudaro richiparadzanisa SA core uye richideredza kuburitswa kwezvigadzirwa zvinoputika zvinobva10. Ganda iri rechar rinoumba chipingamupinyi chemuviri panguva yekuora kwekupisa, richideredza kuchinja kwemamorekuru anobvira kuita gasi phase66,67. Pamusoro peizvi, tinogonawo kuona mhedzisiro yakakura yekurasikirwa nehuremu: SATEOS1 inoratidza hunhu hwakaderera zvichienzaniswa neSATEOS3, SATEOS6 neSA. Izvi zvinodaro nekuti huwandu hweSA muSATEOS1 hwakaderera pane muSATEOS3 neSATEOS6, uko goko reSiO2 rinoumba goko rakakora. Kusiyana neizvi, kurasikirwa kwehuremu kweSA yakawanda kunosvika 99.50% pa415 °C. Zvisinei, SATEOS1, SATEOS3, naSATEOS6 vakaratidza kudzikira kwehuremu ne62.50%, 85.50%, uye 93.76%, zvichiteerana, pa415 °C. Mhedzisiro iyi inoratidza kuti kuwedzerwa kweTEOS kunovandudza kudzikira kweSA nekugadzira SiO2 layer pamusoro peSA. Aya ma layer anogona kuumba chidziviriro chemuviri, uye nekudaro kuvandudzwa kwekugadzikana kwekupisa kwe microencapsulated CA kunogona kuonekwa.
Mhedzisiro yekuvimbika kwekupisa kweSA yakawanda uye sampuro yakanakisa ye microencapsulated (kureva SATEOS 6) mushure memakumi matatu ekudziya nekutonhodza kweDSC51,52 inoratidzwa muMufananidzo 13. Zvinogona kuonekwa kuti SA yakawanda (Mufananidzo 13a) hairatidzi mutsauko mukunyunguduka kwekushisa. kusimba uye enthalpy kukosha, nepo SATEOS6 (Mufananidzo 13b) isingaratidze mutsauko mukudziya uye enthalpy kukosha kunyangwe mushure mekudziya kwechi30. uye maitiro ekutonhodza. Bulk SA yakaratidza poindi yekunyunguduka ye72.10 °C, tembiricha yekusimba ye64.69 °C, uye kupisa kwekusanganiswa nekusimba mushure mekutenderera kwekutanga kwaive 201.0 J/g uye 194.10 J/g, zvichiteerana. Mushure menguva yechi30, kunyunguduka kwezviyero izvi kwakaderera kusvika pa71.24 °C, tembiricha yekusimba yakaderera kusvika pa63.53 °C, uye kukosha kwe enthalpy kwakaderera ne10%. Kuchinja kwetembiricha yekunyunguduka nekusimba, pamwe nekuderera kwe enthalpy, zvinoratidza kuti bulk CA haina kuvimbika kune zvisiri zve microencapsulation. Zvisinei, mushure mekunge microencapsulation yaitika (SATEOS6), tembiricha yekunyunguduka nekusimba uye enthalpy hazvichinje (Mufananidzo 13b). Kana yangoiswa microcapsulated neSiO2 shells, SA inogona kushandiswa sechinhu chinochinja-chinja mukushandiswa kwekupisa, kunyanya mukuvaka, nekuda kwetembiricha yayo yepamusoro yekunyunguduka nekusimba uye enthalpy yakagadzikana.
Makove eDSC akawanikwa emuenzaniso SA (a) naSATEOS6 (b) padanho rekutanga nerechitatu rekudziisa nekutonhodza.
Muchidzidzo ichi, kuferefeta kwakarongeka kwe microencapsulation kwakaitwa uchishandisa SA sechinhu chikuru uye SiO2 sechinhu chegoko. TEOS inoshandiswa senzira yekutanga kugadzira SiO2 support layer uye protective layer pamusoro peSA. Mushure mekubudirira kwe microencapsulated SA, FT-IR, XRD, XPS, SEM uye EDS zvakawanikwa zvakaratidza kuvapo kweSiO2. Ongororo yeSEM ​​inoratidza kuti sample yeSATEOS6 inoratidza zvidimbu zvakaumbwa zvakanaka zvakakomberedzwa nemagoko eSiO2 pamusoro peSA. Zvisinei, MEPCM ine SA content yakaderera inoratidza agglomeration, izvo zvinoderedza kushanda kwePCM. Ongororo yeXPS yakaratidza kuvapo kweSi-O-Si neSi-OH mu microcapsule samples, izvo zvakaratidza adsorption yeSiO2 pamusoro peSA. Zvichienderana neongororo yekushanda kwekupisa, SATEOS6 inoratidza kugona kwakanyanya kuchengetedza kupisa, nekupisa kwekunyunguduka nekusimba kwe70.37°C uye 64.27°C, zvichiteerana, uye kupisa kwakavanzika kwekunyunguduka nekusimba kwe182.53 J/g uye 160.12 J/g. G. zvichiteerana. Kushanda kwakanyanya kweSATEOS6 pakupaka i86.68%. Kuongorora kweTGA neDSC thermal cycle kwakaratidza kuti SATEOS6 ichiri nekupisa kwakanaka uye kuvimbika kunyangwe mushure memaitiro makumi matatu ekupisa nekutonhodza.
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