Development of bionanocomposites based on PCL/PBS double crystalline blends and carbon nanotubes
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Date
2018
Authors
Gumede, Thandi Patricia
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Journal ISSN
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Publisher
University of the Free State
Abstract in other languages 𝘚𝘤𝘳𝘰𝘭𝘭 𝘥𝘰𝘸𝘯 𝘧𝘰𝘳 𝘈𝘧𝘳𝘪𝘬𝘢𝘢𝘯𝘴, 𝘚𝘦𝘚𝘰𝘵𝘩𝘰 𝘢𝘯𝘥 𝘐𝘴𝘪𝘡𝘶𝘭𝘶
Abstract in other languages 𝘚𝘤𝘳𝘰𝘭𝘭 𝘥𝘰𝘸𝘯 𝘧𝘰𝘳 𝘈𝘧𝘳𝘪𝘬𝘢𝘢𝘯𝘴, 𝘚𝘦𝘚𝘰𝘵𝘩𝘰 𝘢𝘯𝘥 𝘐𝘴𝘪𝘡𝘶𝘭𝘶
Abstract
𝑬𝒏𝒈𝒍𝒊𝒔𝒉
The main purpose of this research was to use commercially available crystalline biobased polymers, namely poly(ε-caprolactone) (PCL) and poly(butylene succinate) (PBS), and introduce polycarbonate (PC)/multi-walled carbon nanotubes (MWCNTs) masterbatch into these polymers in order to provide additional functionalities, especially those associated with electronic applications. All the samples were prepared through melt- mixing in a twin-screw extruder. According to our results, the PCL/PBS blends showed a sea-island morphology with discrete droplets of the minor phase within the matrix of the major phase, indicating immiscibility. The introduction of the PC/MWCNTs masterbatch to PCL, PBS and the PCL/PBS blends showed partial miscibility, where PC-rich, PCL-rich and PBS-rich phases were formed. A number of MWCNTs diffused from the PC-rich phase to the PCL- rich and the PBS-rich phases, although the MWCNTs were mostly agglomerated in the PC-rich phases. However, the extent of partial miscibility was different for each system. The polar component surface energy, interfacial tension and isothermal crystallization results suggested that the MWCNTs would preferably diffuse into the PBS-rich phase, rather than the PCL-rich phase. Standard DSC measurements for the PCL/PBS blends, PCL/(PC/MWCNTs) and PBS/(PC/MWCNTs) nanocomposites demonstrated nucleation effects.
In the PCL/PBS blends, nucleation was ascribed to (1) transference of the impurities from the PCL phase to the PBS phase, and (2) since the PBS crystallizes first, the PCL droplets may have crystallized by surface induced nucleation on the interface with the PBS crystallized matrix and nucleate at the interphase. In the case of the nanocomposites, the nucleation effect was attributed to the MWCNTs that diffused from the PC-rich to the PCL-rich and PBS-rich phases, even though the nucleating efficiency was lower than reported in the literature, which probably was due to the limited phase mixing between the PC-rich, the PCL-rich and PBS-rich phases. For the PCL/PBS/(PC/MWCNTs) nanocomposites, there was a decrease in the Tc values. This was due to the competition between two effects: (1) the partial miscibility of the PC-rich with the PCL-rich and PBS-rich phases, and (2) the nucleation effect of the MWCNTs. The decrease in the Tc values indicated that miscibility was the dominating effect. Isothermal crystallization experiments performed by DSC showed an increase in the overall crystallization rate of PCL with increases in MWCNTs contents, which was the result of their nucleating effect.
However, for the PBS/(PC/MWCNTs) nanocomposites, the crystallization rate increased up to 0.5 wt% MWCNTs, while further increases in MWCNTs loading (and also in PC content) resulted in progressive decreases in crystallization rate. The results were explained through increased MWCNTs aggregation and reduced diffusion rates of PBS chains, as the masterbatch content in the blends increased. In the case of the PCL/PBS/(PC/MWCNTs) nanocomposites, the overall crystallization rates decreased as a result of the competition between the nucleating effect and miscibility. Since the PC-rich phase is partially miscible with the PCL-rich and PBS-rich phases, the PC probably immobilized the PCL and PBS chains and inhibited the rate of crystallization. The thermal conductivities and mechanical strengths of the nanocomposites were generally enhanced compared to those of the neat material. The nanocomposites prepared in this work could be used in applications where electrical conductivity, as well as low weight and tailored mechanical properties, are required.
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𝑨𝒇𝒓𝒊𝒌𝒂𝒂𝒏𝒔 Die hoofdoel van hierdie navorsing was om kommersieel beskikbare kristallyne biogebaseerde polimere, naamlik poli(ε-kaprolaktoon) (PCL) en poli(butileensuksinaat) (PBS), te gebruik en om ’n meesterbondel (master batch) polikarbonaat (PC) of meerwandige koolstofnanobuise (MWCNTs) by hierdie polimere in te voer om bykomende funksionaliteite te verskaf, veral dié wat met elektroniese toepassings geassosieer word. Al die monsters is voorberei deur smeltmenging in 'n dubbelskroef-ekstruder. Volgens ons resultate het die PCL/PBS-mengsels 'n see-eiland morfologie getoon met diskrete druppels van die klein fase in die matriks van die hooffase, wat onmengbaarheid aandui. Die bekendstelling van die PC/MWCNTs-meesterbondel aan PCL, PBS en die PCL/PBS-mengsels het gedeeltelike mengbaarheid getoon, waar PC-ryke, PCL-ryke en PBS-ryke fases gevorm is. 'n Aantal MWCNTs het van die PC-ryke fase na die PCL-ryke en die PBS-ryke fases versprei, alhoewel die MWCNTs meestal in die PC-ryke fases geagglomereer was. Die mate van gedeeltelike mengbaarheid was egter verskillend vir elke stelsel. Die polêre komponent oppervlak energie, grensvlakspanning en isotermiese kristallisasie resultate het voorgestel dat die MWCNTs verkieslik in die PBS-ryke fase sou diffundeer, eerder as die PCL-ryke fase. Standaard DSC-metings vir die PCL/PBS-versnitte, PCL/(PC/MWCNTs) en PBS/(PC/MWCNTs) nanosamestellings het nukleasie-effekte getoon. In die PCL/PBS-mengsels is kernvorming toegeskryf aan (1) oordrag van die onsuiwerhede vanaf die PCL-fase na die PBS-fase, en (2) aangesien die PBS eerste kristalliseer, die PCL-druppels kan gekristalliseer het deur oppervlakgeïnduseerde kernvorming op die koppelvlak met die PBS-gekristalliseerde matriks en kernvormig by die interfase. In die geval van die nanokomposiete is die kernvormingseffek toegeskryf aan die MWCNT'e wat van die PC-ryke na die PCL-ryke en PBS-ryke fases versprei het, selfs al was die kernvormingsdoeltreffendheid laer as wat in die literatuur gerapporteer is, wat waarskynlik te wyte was. tot die beperkte fasevermenging tussen die PC-ryke, die PCL-ryke en PBS-ryke fases. Vir die PCL/PBS/(PC/MWCNTs) nanosamestellings was daar 'n afname in die Tc-waardes. Dit was as gevolg van die mededinging tussen twee effekte: (1) die gedeeltelike mengbaarheid van die PC-ryke met die PCL-ryke en PBS-ryke fases, en (2) die nukleasie-effek van die MWCNTs. Die afname in die Tc-waardes het aangedui dat mengbaarheid die oorheersende effek was. Isotermiese kristallisasie-eksperimente wat deur DSC uitgevoer is, het 'n toename in die algehele kristallisasietempo van PCL getoon met ’n toenames in die MWCNTs-inhoud, wat die gevolg was van hul kernvormingseffek. Vir die PBS/(PC/MWCNTs) nanosamestellings het die kristallisasietempo egter tot 0.5 wt% MWCNTs toegeneem, terwyl verdere toenames in MWCNTs se lading (en ook in PC-inhoud) gelei het tot progressiewe afname in kristallisasietempo. Die resultate is verduidelik deur verhoogde MWCNTs-aggregasie en verlaagde diffusietempo's van PBS-kettings, aangesien die meesterbatch-inhoud in die mengsels toegeneem het. In die geval van die PCL/PBS/(PC/MWCNTs) nanosamestellings, het die algehele kristallisasietempo's afgeneem as gevolg van die kompetisie tussen die kernvormingseffek en mengbaarheid. Aangesien die PC-ryke fase gedeeltelik mengbaar is met die PCL-ryke en PBS-ryke fases, het die PC waarskynlik die PCL- en PBS-kettings geïmmobiliseer en die tempo van kristallisasie geïnhibeer. Die termiese geleidingsvermoë en meganiese sterkte van die nanosamestellings is oor die algemeen verbeter in vergelyking met dié van die netjiese materiaal. Die nanosamestellings wat in hierdie werk voorberei is, kan gebruik word in toepassings waar elektriese geleidingsvermoë, sowel as lae gewig en pasgemaakte meganiese eienskappe, vereis word. ___________________________________________________________________
𝑺𝒆𝑺𝒐𝒕𝒉𝒐 Sepheo se seholo sa diphuputso tsena ke ho sebedisa mahakwe a kgwebo a fumanehang a biobased polymers, e leng poly (ε-caprolactone) (PCL) le poly (butylene succinate) (PBS), le ho hlahisa polycarbonate (PC)/multi-walled carbon nanotubes (MWCNTs) masterbatch ka hara polymers tsena e le ho fana ka mesebetsi e eketsehileng, haholoholo e amanang le ditshebeletso tsa elektroniki. Disampole tsohle di hlophisitswe ka ho tswakwa ka ho qhibidihiswa ka motjhini o sothwang ho theha sebopeho. Ho ya ka diphetho tsa rona, metswako ya PCL/PBS e bontshitse sebopeho se kang ‘sehlekehleke ka hara lewatle’ mme ho na le marothodinyana a sa fetoheng a sebopeho sa kgato e nyenyane ka hara kgato e kgolo, ho bontsha ho se tshwane. Tlhahiso ya PC/MWCNTs masterbatch ho PCL, PBS le metswako ya PCL/PBS di bontshitse ho tshwana hanyenyane, e leng moo dikgato tsa PC-rich, PCL-rich le PBS-rich di theilweng teng. Bongata ba di-MWCNT bo kopane ho tswa ho kgato ya PC-rich ho isa ho PCLrich le dikgato tsa PBS-rich, le hoja bongata ba di-MWCNT bo kopantswe ka hara dikgato tsa PC-rich. Leha ho le jwalo, boemo ba ho tshwana ho fokolang ho fapane bakeng sa tshebetso ka nngwe. Eneji ya karolo ya sebaka se ka hodimo, tsitsipano ya kamano le diphetho tsa ho thehwa ha mahakwe a isothermal di hlakisa hore di-MWCNT di tla kgahlwa ke ho amanywa ka hara kgato ya PBS-rich, ho na le kgato ya PCL-rich. Ditekanyetso tse tlwaelehileng tsa DSC bakeng sa ho tswaka PCL/PBS, PCL/(PC/MWCNTs) le PBS/(PC/MWCNTs) nanocomposites di bontshitse ditlamorao tsa nucleation. Ka hara metswako ya PCL/PBS, nucleation e amantswe le (1) phetiso ya ditshila tse tswang kgatong ya PCL ho isa kgatong ya PBS, le (2) ka lebaka la hobane PBS e theha mahakwe pele, marothodi a PCL e ka nna ya ba marothodi a fetohileng mahakwe e bile a fetohile ka hodimo mme marothodi a fetohile mahakwe ka nucleation ya kopano le PBS crystallized matrix hammoho le kopano le nucleate ho kopano eo ya bobedi. Boemong ba nanocomposites, ditlamorao tsa nucleation di amantswe le di-MWCNT tse qhibidihileng ho tswa ho dikgato tsa PC-rich ho isa ho PCL-rich hammoho le PBS-rich, leha bohlwahlwa ba nucleation bo le tlase hanyenyane ho feta kamoo bo bolelwang dingolweng, e neng e le ka lebaka la kgato e lekanyeditsweng ya motswako pakeng tsa dikgato tsa PC-rich, PCL-rich le PBS-rich. Bakeng sa PCL/PBS/(PC/MWCNTs) nanocomposites, ho ne ho na le phokotseho ya makgabane a Tc. Hona ho ne ho bakwa ke tlhodisano pakeng tsa ditlamorao tse pedi: (1) ho nwelella ho ya ka karolo e itseng ha PC-rich ka dikgato tsa PCL-rich le PBS-rich, le (2) ditlamorao tsa nucleation tsa MWCNTs. Phokotseho ya makgabane a Tc e bontshitse hore ho nwelella e ne e letshwao le leholo. Diteko tsa isothermal crystallization tse entsweng ke DSC di bontshitse keketseho ya tekanyetso ya ho thehwa ha mahakwe ka kakaretso ha PCL ka keketseho ya dikateng tsa di-MWCNT, tseo e neng e le sephetho sa ditlamorao tsa nucleation. Leha ho le jwalo, bakeng sa PBS/(PC/MWCNTs) nanocomposites, tekanyetso ya ketso ya mahakwe e eketsehile ho a fihla ho 0.5 wt% MWCNTs, ha dikeketseho tse ding tsa di-MWCNT (hape le tse ka hare tsa PC) di bakile phokotseho ya tekanyetso ya ketso ya mahakwe. Diphetho di hlalositswe ho ya ka keketseho ya tekanyetso ya palohare ya di-MWCNT le ditekanyetso tse fokoditsweng tsa ho qhibidiha tsa diketane tsa PBS, e le dikateng tsa masterbatch ka hara metswako e ekeditsweng. Boemong ba PCL/PBS/(PC/MWCNTs) nanocomposites, ditekanyetso tsohle tsa ketso ya mahakwe di fokotsehile ka lebaka la tlhodisano pakeng tsa ditlamorao tsa nucleation esita le ho nwelella. Erekaha kgato ya PC-rich e batla e kgona ho nwelella ho kopana le dikgato tsa PCL-rich le PBS-rich, PC e batla e sitisitse PCL le diketane tsa PBS mme e thibetse tekanyetso ya ketso ya mahakwe. The thermal conductivities le matla a metjhini ya di-nanocomposite ka kakaretso di ne di bapiswa le tsa thepa e hlwekileng. Di-Nanocomposite tse hlophisitsweng mosebetsing ona di ne di ka sebediswa bakeng sa tshebetso tse fapaneng moo ho hlokehang tsamaiso ka motlakase esita le boima bo tlase le matshwao a entsweng a metjhini ka kakaretso. ___________________________________________________________________
𝑰𝒔𝒊𝒁𝒖𝒍𝒖 Inhloso enkulu yalolu cwaningo bekuwukusebenzisa amacrystalline biobased polymers athengiswayo, okuyipoly(ε-caprolactone) (PCL) kanye ne poly(butylene succinate) (PBS), kanye nokwethula ipolycarbonate (PC)/multi-walled carbon nanotubes (MWCNTs) imasterbatch kulawa mapolymers ukuze unikeze imisebenzi eyengeziwe, ikakhulukazi leyo ehlotshaniswa nezinhlelo zokusebenza ze-elekthronikhi. Wonke amasampuli alungiswa ngokuxutshwa okuncibilikisayo kwitwin-screw extruder. Ngokwemiphumela yethu, izingxube ze-PCL/PBS zibonise imofoloji ye-sea-island enamaconsi ahlukene esigaba esincane ngaphakathi kwematrix yesigaba esikhulu, okubonisa ukungahambi kahle. Ukwethulwa kwe-PC/MWCNTs masterbatch ku-PCL, i-PBS kanye nezingxube ze-PCL/PBS kubonise ukungezwani okuyingxenye, lapho kwakhiwa khona izigaba zePC-rich, iPCL- rich kanye nePBS-rich. Inani lamaMWCNTs ahlukanisiwe kusukela kusigaba iPC-rich kuya kwi-PCLrich kanye nezigaba ezicebile zePBS-rich, nakuba amaMWCNT ayehlanganiswe kakhulu ezigabeni zePC-rich. Kodwa-ke, izinga lokungahleleki kahle ngokwengxenye lalihlukile kusistimu ngayinye. Ingxenye yepolar yamandla angaphezulu, ukungezwani phakathi kwalapho kuhlangana khona amasistimu kanye nemiphumela ye-isothermal crystallization iphakamise ukuthi amaMWCNTs angahle asakazeke esigabeni sePBS-rich, kunesigaba sePCL-rich. Izilinganiso ezijwayelekile ze-DSC zokuhlanganisa i-PCL/PBS, i-PCL/(PC/MWCNTs) kanye namananocomposites e-PBS/(PC/MWCNTs) abonise imiphumela yenucleation. Emixubeni ye-PCL/PBS, inucleation kwathiwa (1) ukudluliselwa kokungcola kusuka esigabeni se-PCL kuya esigabeni se-PBS, futhi (2) njengoba i-PBS icwebezela kuqala, amaconsi e-PCL angase acwebezeliswe yinucleation eyenziwe phezulu esibonakalayo. Nge-PBS crystallized matrix kanye nenucleate lapho kuhlangana khona amasistimu. Endabeni ye-nanocomposites, umphumela wenucleation ubizwa ngokuthi iMWCNTs eyahlukana nePC-rich kuya ezigabeni ezicebile ze-PCL kanye ne-PBS, nakuba ukusebenza kahle kwenucleating kwakungaphansi kunalokho okubikwe ezincwadini, okungenzeka ukuthi kwakungenxa yokuhlanganiswa kwesigaba esilinganiselwe phakathi kwezigaba zePC-rich, iPCL-rich kanye nePBS-rich. Kumananocomposites e-PCL/PBS/(PC/MWCNTs), kube nokwehla kwamanani e-Tc. Lokhu kwakungenxa yokuncintisana phakathi kwemiphumela emibili: (1) ukungezwani okuyingxenye kwePC-rich ngezigaba zePCL-rich kanye nePBS-rich, kanye (2) nomphumela wenucleation we-MWCNTs. Ukuncipha kwamanani e-Tc kubonise ukuthi ukuhlukahluka kwakuwumphumela obusayo. Ukuhlolwa kwe-Isothermal crystallization okwenziwa yi-DSC kubonise ukwenyuka kwezinga lecrystallization eliphelele le-PCL ngokunyuka kokuqukethwe kwe-MWCNTs, okuwumphumela womphumela wabo wenucleating. Kodwa-ke, kumananocomposites e-PBS/(PC/MWCNTs), izinga lokucwebezela likhuphuke lafika kumaphesenti ayi-0.5 wt MWCNTs, kuyilapho ukwanda okwengeziwe ekulayisheni kweMWCNTs (kanye nokuqukethwe kwePC) kubangele ukwehla okuqhubekayo kwezinga lokucwebezela. Imiphumela yachazwa ngokwenyuka kokuhlanganisa kwe-MWCNTs kanye namazinga ancishisiwe okusabalalisa amaketango ePBS, njengoba okuqukethwe kwemasterbatch ekuhlanganisweni kwanda. Endabeni yePCL/PBS/(PC/MWCNTs) nanocomposites, amazinga ecrystallization jikelele ehla ngenxa yokuncintisana phakathi komthelela wenucleating kanye nokungahleleki. Njengoba isigaba iPC-rich sixubene ngokwengxenye nezigaba ezicebile ze-PCL kanye nePBS-rich, iPC cishe yavala amaketanga ePCL nePBS futhi yavimbela izinga lecrystallization. Ukulawulwa kukagesi kunamandla emishini yamananocomposites ngokuvamile athuthukisiwe uma kuqhathaniswa nalawo ezinto ezihlanzekile. Amananocomposites alungiselelwe kulo msebenzi angasetshenziswa ezinhlelweni zokusebenza lapho ukuqhutshwa kukagesi, kanye nesisindo esincane kanye nezakhiwo zemishini ezilungiselelwe, kudingeka. ___________________________________________________________________
𝑨𝒇𝒓𝒊𝒌𝒂𝒂𝒏𝒔 Die hoofdoel van hierdie navorsing was om kommersieel beskikbare kristallyne biogebaseerde polimere, naamlik poli(ε-kaprolaktoon) (PCL) en poli(butileensuksinaat) (PBS), te gebruik en om ’n meesterbondel (master batch) polikarbonaat (PC) of meerwandige koolstofnanobuise (MWCNTs) by hierdie polimere in te voer om bykomende funksionaliteite te verskaf, veral dié wat met elektroniese toepassings geassosieer word. Al die monsters is voorberei deur smeltmenging in 'n dubbelskroef-ekstruder. Volgens ons resultate het die PCL/PBS-mengsels 'n see-eiland morfologie getoon met diskrete druppels van die klein fase in die matriks van die hooffase, wat onmengbaarheid aandui. Die bekendstelling van die PC/MWCNTs-meesterbondel aan PCL, PBS en die PCL/PBS-mengsels het gedeeltelike mengbaarheid getoon, waar PC-ryke, PCL-ryke en PBS-ryke fases gevorm is. 'n Aantal MWCNTs het van die PC-ryke fase na die PCL-ryke en die PBS-ryke fases versprei, alhoewel die MWCNTs meestal in die PC-ryke fases geagglomereer was. Die mate van gedeeltelike mengbaarheid was egter verskillend vir elke stelsel. Die polêre komponent oppervlak energie, grensvlakspanning en isotermiese kristallisasie resultate het voorgestel dat die MWCNTs verkieslik in die PBS-ryke fase sou diffundeer, eerder as die PCL-ryke fase. Standaard DSC-metings vir die PCL/PBS-versnitte, PCL/(PC/MWCNTs) en PBS/(PC/MWCNTs) nanosamestellings het nukleasie-effekte getoon. In die PCL/PBS-mengsels is kernvorming toegeskryf aan (1) oordrag van die onsuiwerhede vanaf die PCL-fase na die PBS-fase, en (2) aangesien die PBS eerste kristalliseer, die PCL-druppels kan gekristalliseer het deur oppervlakgeïnduseerde kernvorming op die koppelvlak met die PBS-gekristalliseerde matriks en kernvormig by die interfase. In die geval van die nanokomposiete is die kernvormingseffek toegeskryf aan die MWCNT'e wat van die PC-ryke na die PCL-ryke en PBS-ryke fases versprei het, selfs al was die kernvormingsdoeltreffendheid laer as wat in die literatuur gerapporteer is, wat waarskynlik te wyte was. tot die beperkte fasevermenging tussen die PC-ryke, die PCL-ryke en PBS-ryke fases. Vir die PCL/PBS/(PC/MWCNTs) nanosamestellings was daar 'n afname in die Tc-waardes. Dit was as gevolg van die mededinging tussen twee effekte: (1) die gedeeltelike mengbaarheid van die PC-ryke met die PCL-ryke en PBS-ryke fases, en (2) die nukleasie-effek van die MWCNTs. Die afname in die Tc-waardes het aangedui dat mengbaarheid die oorheersende effek was. Isotermiese kristallisasie-eksperimente wat deur DSC uitgevoer is, het 'n toename in die algehele kristallisasietempo van PCL getoon met ’n toenames in die MWCNTs-inhoud, wat die gevolg was van hul kernvormingseffek. Vir die PBS/(PC/MWCNTs) nanosamestellings het die kristallisasietempo egter tot 0.5 wt% MWCNTs toegeneem, terwyl verdere toenames in MWCNTs se lading (en ook in PC-inhoud) gelei het tot progressiewe afname in kristallisasietempo. Die resultate is verduidelik deur verhoogde MWCNTs-aggregasie en verlaagde diffusietempo's van PBS-kettings, aangesien die meesterbatch-inhoud in die mengsels toegeneem het. In die geval van die PCL/PBS/(PC/MWCNTs) nanosamestellings, het die algehele kristallisasietempo's afgeneem as gevolg van die kompetisie tussen die kernvormingseffek en mengbaarheid. Aangesien die PC-ryke fase gedeeltelik mengbaar is met die PCL-ryke en PBS-ryke fases, het die PC waarskynlik die PCL- en PBS-kettings geïmmobiliseer en die tempo van kristallisasie geïnhibeer. Die termiese geleidingsvermoë en meganiese sterkte van die nanosamestellings is oor die algemeen verbeter in vergelyking met dié van die netjiese materiaal. Die nanosamestellings wat in hierdie werk voorberei is, kan gebruik word in toepassings waar elektriese geleidingsvermoë, sowel as lae gewig en pasgemaakte meganiese eienskappe, vereis word. ___________________________________________________________________
𝑺𝒆𝑺𝒐𝒕𝒉𝒐 Sepheo se seholo sa diphuputso tsena ke ho sebedisa mahakwe a kgwebo a fumanehang a biobased polymers, e leng poly (ε-caprolactone) (PCL) le poly (butylene succinate) (PBS), le ho hlahisa polycarbonate (PC)/multi-walled carbon nanotubes (MWCNTs) masterbatch ka hara polymers tsena e le ho fana ka mesebetsi e eketsehileng, haholoholo e amanang le ditshebeletso tsa elektroniki. Disampole tsohle di hlophisitswe ka ho tswakwa ka ho qhibidihiswa ka motjhini o sothwang ho theha sebopeho. Ho ya ka diphetho tsa rona, metswako ya PCL/PBS e bontshitse sebopeho se kang ‘sehlekehleke ka hara lewatle’ mme ho na le marothodinyana a sa fetoheng a sebopeho sa kgato e nyenyane ka hara kgato e kgolo, ho bontsha ho se tshwane. Tlhahiso ya PC/MWCNTs masterbatch ho PCL, PBS le metswako ya PCL/PBS di bontshitse ho tshwana hanyenyane, e leng moo dikgato tsa PC-rich, PCL-rich le PBS-rich di theilweng teng. Bongata ba di-MWCNT bo kopane ho tswa ho kgato ya PC-rich ho isa ho PCLrich le dikgato tsa PBS-rich, le hoja bongata ba di-MWCNT bo kopantswe ka hara dikgato tsa PC-rich. Leha ho le jwalo, boemo ba ho tshwana ho fokolang ho fapane bakeng sa tshebetso ka nngwe. Eneji ya karolo ya sebaka se ka hodimo, tsitsipano ya kamano le diphetho tsa ho thehwa ha mahakwe a isothermal di hlakisa hore di-MWCNT di tla kgahlwa ke ho amanywa ka hara kgato ya PBS-rich, ho na le kgato ya PCL-rich. Ditekanyetso tse tlwaelehileng tsa DSC bakeng sa ho tswaka PCL/PBS, PCL/(PC/MWCNTs) le PBS/(PC/MWCNTs) nanocomposites di bontshitse ditlamorao tsa nucleation. Ka hara metswako ya PCL/PBS, nucleation e amantswe le (1) phetiso ya ditshila tse tswang kgatong ya PCL ho isa kgatong ya PBS, le (2) ka lebaka la hobane PBS e theha mahakwe pele, marothodi a PCL e ka nna ya ba marothodi a fetohileng mahakwe e bile a fetohile ka hodimo mme marothodi a fetohile mahakwe ka nucleation ya kopano le PBS crystallized matrix hammoho le kopano le nucleate ho kopano eo ya bobedi. Boemong ba nanocomposites, ditlamorao tsa nucleation di amantswe le di-MWCNT tse qhibidihileng ho tswa ho dikgato tsa PC-rich ho isa ho PCL-rich hammoho le PBS-rich, leha bohlwahlwa ba nucleation bo le tlase hanyenyane ho feta kamoo bo bolelwang dingolweng, e neng e le ka lebaka la kgato e lekanyeditsweng ya motswako pakeng tsa dikgato tsa PC-rich, PCL-rich le PBS-rich. Bakeng sa PCL/PBS/(PC/MWCNTs) nanocomposites, ho ne ho na le phokotseho ya makgabane a Tc. Hona ho ne ho bakwa ke tlhodisano pakeng tsa ditlamorao tse pedi: (1) ho nwelella ho ya ka karolo e itseng ha PC-rich ka dikgato tsa PCL-rich le PBS-rich, le (2) ditlamorao tsa nucleation tsa MWCNTs. Phokotseho ya makgabane a Tc e bontshitse hore ho nwelella e ne e letshwao le leholo. Diteko tsa isothermal crystallization tse entsweng ke DSC di bontshitse keketseho ya tekanyetso ya ho thehwa ha mahakwe ka kakaretso ha PCL ka keketseho ya dikateng tsa di-MWCNT, tseo e neng e le sephetho sa ditlamorao tsa nucleation. Leha ho le jwalo, bakeng sa PBS/(PC/MWCNTs) nanocomposites, tekanyetso ya ketso ya mahakwe e eketsehile ho a fihla ho 0.5 wt% MWCNTs, ha dikeketseho tse ding tsa di-MWCNT (hape le tse ka hare tsa PC) di bakile phokotseho ya tekanyetso ya ketso ya mahakwe. Diphetho di hlalositswe ho ya ka keketseho ya tekanyetso ya palohare ya di-MWCNT le ditekanyetso tse fokoditsweng tsa ho qhibidiha tsa diketane tsa PBS, e le dikateng tsa masterbatch ka hara metswako e ekeditsweng. Boemong ba PCL/PBS/(PC/MWCNTs) nanocomposites, ditekanyetso tsohle tsa ketso ya mahakwe di fokotsehile ka lebaka la tlhodisano pakeng tsa ditlamorao tsa nucleation esita le ho nwelella. Erekaha kgato ya PC-rich e batla e kgona ho nwelella ho kopana le dikgato tsa PCL-rich le PBS-rich, PC e batla e sitisitse PCL le diketane tsa PBS mme e thibetse tekanyetso ya ketso ya mahakwe. The thermal conductivities le matla a metjhini ya di-nanocomposite ka kakaretso di ne di bapiswa le tsa thepa e hlwekileng. Di-Nanocomposite tse hlophisitsweng mosebetsing ona di ne di ka sebediswa bakeng sa tshebetso tse fapaneng moo ho hlokehang tsamaiso ka motlakase esita le boima bo tlase le matshwao a entsweng a metjhini ka kakaretso. ___________________________________________________________________
𝑰𝒔𝒊𝒁𝒖𝒍𝒖 Inhloso enkulu yalolu cwaningo bekuwukusebenzisa amacrystalline biobased polymers athengiswayo, okuyipoly(ε-caprolactone) (PCL) kanye ne poly(butylene succinate) (PBS), kanye nokwethula ipolycarbonate (PC)/multi-walled carbon nanotubes (MWCNTs) imasterbatch kulawa mapolymers ukuze unikeze imisebenzi eyengeziwe, ikakhulukazi leyo ehlotshaniswa nezinhlelo zokusebenza ze-elekthronikhi. Wonke amasampuli alungiswa ngokuxutshwa okuncibilikisayo kwitwin-screw extruder. Ngokwemiphumela yethu, izingxube ze-PCL/PBS zibonise imofoloji ye-sea-island enamaconsi ahlukene esigaba esincane ngaphakathi kwematrix yesigaba esikhulu, okubonisa ukungahambi kahle. Ukwethulwa kwe-PC/MWCNTs masterbatch ku-PCL, i-PBS kanye nezingxube ze-PCL/PBS kubonise ukungezwani okuyingxenye, lapho kwakhiwa khona izigaba zePC-rich, iPCL- rich kanye nePBS-rich. Inani lamaMWCNTs ahlukanisiwe kusukela kusigaba iPC-rich kuya kwi-PCLrich kanye nezigaba ezicebile zePBS-rich, nakuba amaMWCNT ayehlanganiswe kakhulu ezigabeni zePC-rich. Kodwa-ke, izinga lokungahleleki kahle ngokwengxenye lalihlukile kusistimu ngayinye. Ingxenye yepolar yamandla angaphezulu, ukungezwani phakathi kwalapho kuhlangana khona amasistimu kanye nemiphumela ye-isothermal crystallization iphakamise ukuthi amaMWCNTs angahle asakazeke esigabeni sePBS-rich, kunesigaba sePCL-rich. Izilinganiso ezijwayelekile ze-DSC zokuhlanganisa i-PCL/PBS, i-PCL/(PC/MWCNTs) kanye namananocomposites e-PBS/(PC/MWCNTs) abonise imiphumela yenucleation. Emixubeni ye-PCL/PBS, inucleation kwathiwa (1) ukudluliselwa kokungcola kusuka esigabeni se-PCL kuya esigabeni se-PBS, futhi (2) njengoba i-PBS icwebezela kuqala, amaconsi e-PCL angase acwebezeliswe yinucleation eyenziwe phezulu esibonakalayo. Nge-PBS crystallized matrix kanye nenucleate lapho kuhlangana khona amasistimu. Endabeni ye-nanocomposites, umphumela wenucleation ubizwa ngokuthi iMWCNTs eyahlukana nePC-rich kuya ezigabeni ezicebile ze-PCL kanye ne-PBS, nakuba ukusebenza kahle kwenucleating kwakungaphansi kunalokho okubikwe ezincwadini, okungenzeka ukuthi kwakungenxa yokuhlanganiswa kwesigaba esilinganiselwe phakathi kwezigaba zePC-rich, iPCL-rich kanye nePBS-rich. Kumananocomposites e-PCL/PBS/(PC/MWCNTs), kube nokwehla kwamanani e-Tc. Lokhu kwakungenxa yokuncintisana phakathi kwemiphumela emibili: (1) ukungezwani okuyingxenye kwePC-rich ngezigaba zePCL-rich kanye nePBS-rich, kanye (2) nomphumela wenucleation we-MWCNTs. Ukuncipha kwamanani e-Tc kubonise ukuthi ukuhlukahluka kwakuwumphumela obusayo. Ukuhlolwa kwe-Isothermal crystallization okwenziwa yi-DSC kubonise ukwenyuka kwezinga lecrystallization eliphelele le-PCL ngokunyuka kokuqukethwe kwe-MWCNTs, okuwumphumela womphumela wabo wenucleating. Kodwa-ke, kumananocomposites e-PBS/(PC/MWCNTs), izinga lokucwebezela likhuphuke lafika kumaphesenti ayi-0.5 wt MWCNTs, kuyilapho ukwanda okwengeziwe ekulayisheni kweMWCNTs (kanye nokuqukethwe kwePC) kubangele ukwehla okuqhubekayo kwezinga lokucwebezela. Imiphumela yachazwa ngokwenyuka kokuhlanganisa kwe-MWCNTs kanye namazinga ancishisiwe okusabalalisa amaketango ePBS, njengoba okuqukethwe kwemasterbatch ekuhlanganisweni kwanda. Endabeni yePCL/PBS/(PC/MWCNTs) nanocomposites, amazinga ecrystallization jikelele ehla ngenxa yokuncintisana phakathi komthelela wenucleating kanye nokungahleleki. Njengoba isigaba iPC-rich sixubene ngokwengxenye nezigaba ezicebile ze-PCL kanye nePBS-rich, iPC cishe yavala amaketanga ePCL nePBS futhi yavimbela izinga lecrystallization. Ukulawulwa kukagesi kunamandla emishini yamananocomposites ngokuvamile athuthukisiwe uma kuqhathaniswa nalawo ezinto ezihlanzekile. Amananocomposites alungiselelwe kulo msebenzi angasetshenziswa ezinhlelweni zokusebenza lapho ukuqhutshwa kukagesi, kanye nesisindo esincane kanye nezakhiwo zemishini ezilungiselelwe, kudingeka. ___________________________________________________________________
Description
Thesis (Ph.D.(Chemistry))--University of the Free State, 2018
Keywords
Crystalline biobased polymers, Poly(ε-caprolactone) (PCL), Poly(butylene succinate) (PBS), Electronic applications