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Aluminium oxide - poly(ethylene-co-butylacrylate) nanocomposites: synthesis, structure, transport properties and long-term performance
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Polymer nanocomposites are promising materials for dielectrical use in high voltage applications and insulations. This work presents a study of nanocomposites based on poly(ethylene-co-butyl acrylate) with two different comonomer compositions and two different aluminium oxide nanoparticles. The nanoparticles were either untreated, or surface-treated with two different silanes, aminopropyl triethoxy silane and octyltriethoxy silane. The best level of dispersion was found for the polymer with 13 wt. % of butyl acrylate (EBA-13) whereas the low melt viscosity of the polymer with 28 wt. % of butyl acrylate (EBA-28) resulted in insufficient mixing with uneven dispersion as a result. Octyltriethoxy silane-treated particles were best dispersed in the polymer. The nanoparticles acted as nucleation agents in EBA-28, increasing the crystallization temperature by several degrees. Studies of the water uptake in the nanocomposite materials showed the effect of the enormous interfacial surfaces and great number of polar groups present on the nanoparticle surfaces. For the well-dispersed nanomaterials, the water sorption data could be modeled by a single Fickian equation, whereas materials that contained a sizeable fraction of large nanoparticle agglomerates showed a two stage sorption process, first a fast process associated with the saturation of the polymer phase and second, a slow diffusion process due to water sorption of large particle agglomerates. The long-term performance and interaction between the nanoparticles and the phenolic antioxidant (Irganox 1010) was investigated by differential scanning calorimetry in order to assess the oxidation induction time (OIT); the latter being proportional to the concentration of efficient antioxidant. It was found that the stabilizer was adsorbed to the untreated Al2O3 nanoparticles, resulting in a significant reduction in OIT. However, silanization of the nanoparticles resulted in an increase in OIT, compared to the materials containing untreated particles. Furthermore, it was shown that the stabilizer was not irreversibly adsorbed to the particles, allowing a gradual release of stabilizer with ageing time.

Abstract [sv]

Polymera nanokompositer är lovande material för användning som dielektriskt material inom högspänningsområdet. I detta arbete studeras nanokompositer framställda av två olika sampolymerer av eten och butylakrylat (EBA-13 med 13 vikt% butylakrylat samt EBA-28 med 28 vikt% och två olika typer av nanopartiklar av Al2O3. Nanopartiklarna användes antingen som obehandlade eller efter silanisering med aminopropyltrietoxysilan- eller oktyltrietoxysilan. Den bästa partikeldispergeringen observerades för de material som baserats på EBA-13 medan den låga smältviskositeten hos EBA-28 resulterade i låga skjuvkrafter under kompounderingen och en observerat ojämn dispergering och förekomst av mikrometerstora agglomerat. Partiklar som silaniserats med oktyltrietoxysilan var lättast att dispergera. Nanopartiklarna fungerade som kärnbildare i EBA-28 vilket medförde en höjning av kristallisationstemperaturen. Vattensorptionsstudier demonstrerade dels effekten av den stora specifika gränsytan mellan partikel och matris och dels av förekomst av polära grupper lokaliserade till nämnda gränsyta. Kompositer med väldispergerade partiklar uppvisade en enkel Ficksk sorptionsprocess medan de material som innehöll en betydande mängd stora agglomerat påvisade en tvådelad process. Den första processen var kopplad till mättningen av polymermatrisen och den andra kunde länkas till vattenupptaget i de stora agglomeraten. Vidare undersöktes långtidsegenskaperna hos nanokompositerna, samt om det fanns någon växelverkan mellan nanopartiklar och en fenolbaserade antioxidant (Irganox 1010). DSC användes för att bestämma induktionstiden för oxidation (OIT) vilket är ett mått på koncentrationen av aktiv fenolisk antioxidant. Det framgick det att Irganox 1010 adsorberades på nanopartiklarna, vilket ledde till en minskning av OIT. Det framgick även att de material som innehöll silaniserade nanopartiklar hade högre OIT jämfört material med obehandlade partiklar. Antioxidanten var däremot inte irreversibelt bunden till nanopartiklarna, utan frigjordes från deras ytor och blev aktiv under åldringen.

Place, publisher, year, edition, pages
Stockholm: US-AB , 2011. , 43 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2011:3
Keyword [en]
nanocomposite, nanoparticles, aluminium oxide, poly(ethylene-co-butyl acrylate), silanization, dispersion, Irganox 1010, antioxidant, OIT, sorption kinetics, water
Keyword [sv]
nanokomposit, nanopartiklar, aluminium oxid, poly(eten-co-butyl akrylat), silanisering, dispergering, Irganox 1010, antioxidant, OIT, vattenupptag.
Identifiers
URN: urn:nbn:se:kth:diva-29270ISBN: 978-91-7415-827-4 (print)OAI: oai:DiVA.org:kth-29270DiVA: diva2:393507
Presentation
2011-01-28, Rångbyrummet, KTH, Teknikringen 56, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20110128Available from: 2011-01-31 Created: 2011-01-31 Last updated: 2011-01-31Bibliographically approved
List of papers
1. Preparation and characterization of aluminum oxide-poly(ethylene-co-butyl acrylate) nanocomposites
Open this publication in new window or tab >>Preparation and characterization of aluminum oxide-poly(ethylene-co-butyl acrylate) nanocomposites
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2012 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 125, no 2, 975-983 p.Article in journal (Refereed) Published
Abstract [en]

This article describes the preparation and characterization of composites containing poly(ethylene-co-butyl acrylate) (EBA13 and EBA28 with 13 and 28 wt % butyl acrylate, respectively) and 212 wt % (0.53 vol %) of aluminum oxide nanoparticles (two types differing in specific surface area and hydroxyl-group concentration; uncoated and coated with, respectively, octyltriethoxysilane and aminopropyltriethoxysilane). A greater surface coverage was obtained with aminopropyltriethoxysilane than with octyltriethoxysilane. An overall good dispersion was obtained in the EBA-13 composites prepared by extrusion compounding. Composites with octyltriethoxysilane-coated nanoparticles showed the best dispersion. The addition of the nanoparticles to EBA28 resulted in poor dispersion, probably due to insufficiently high shear forces acting during extrusion mixing which were unable to break down nanoparticle agglomerates. The nanoparticles had no effect on the crystallization kinetics in the EBA13 composites, but in the EBA28 composites the presence of the nanoparticles led to an increase in the crystallization peak temperature, suggesting that the nanoparticles had a nucleating effect in this particular polymer.

Keyword
poly(ethylene-co-butyl acrylate), aluminium oxide nanoparticles, nanocomposites, silanization, dispersion, crystallization
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-28775 (URN)10.1002/app.36331 (DOI)000302350300018 ()2-s2.0-84859579887 (Scopus ID)
Funder
Swedish Research Council, IFA 2007-5095
Note
QC 20120508Available from: 2011-01-21 Created: 2011-01-21 Last updated: 2017-12-11Bibliographically approved
2. Water transport in aluminium oxide-poly(ethylene-co-butylacrylate) nanocomposites
Open this publication in new window or tab >>Water transport in aluminium oxide-poly(ethylene-co-butylacrylate) nanocomposites
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2011 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 47, no 12, 2208-2215 p.Article in journal (Refereed) Published
Abstract [en]

Polymer composites with metal oxide nanoparticles are emerging materials to be used as insulations in electrical applications. However, the extensive interfacial surfaces and the presence of polar groups on the particle surfaces make these composites susceptible to water sorption. Water sorption kinetics data were taken at 23 °C and different relative humidities (18 to 90 %) for composites based on poly(ethylene-co-butyl acrylate) and aluminium oxide; the latter were in three different forms: uncoated and coated with either octyltriethoxy silane or aminopropyl triethoxy silane). The equilibrium water uptake increased in a linear fashion with increasing concentration of polar groups present on the nanoparticle surfaces. Composites with well-dispersed nanoparticles showed a Fickian sorption process with a diffusivity that decreased with increasing filler content. This effect was most pronounced for composites with accessible polar groups on the particle surfaces suggesting that water saturation of the composites is retarded by dual water sorption. Composites that contained a sizeable fraction of large nanoparticle agglomerates showed a two stage sorption process: a fast process associated the saturation of the matrix phase and slow diffusion process due to water sorption of the large nanoparticle agglomerates.

 

Keyword
Poly(ethylene-co-butyl acrylate), aluminium oxide, nanocomposites, water, sorption kinetics
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-28779 (URN)10.1016/j.eurpolymj.2011.09.013 (DOI)000298204500004 ()2-s2.0-81155154434 (Scopus ID)
Note
QC 20110121. Updated from submitted to published 20120125Available from: 2011-01-21 Created: 2011-01-21 Last updated: 2017-12-11Bibliographically approved
3. Stabilizer activity in Al2O3/ poly(ethylene-co-butylacrylate) nanocomposites
Open this publication in new window or tab >>Stabilizer activity in Al2O3/ poly(ethylene-co-butylacrylate) nanocomposites
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(English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Article in journal (Other academic) Submitted
Abstract [en]

The stabilizer activity of polymer nanocomposites based on poly(ethylene-co-butylacrylate) and 0.5 - 3 vol. % of two different types of Al2O3 nanoparticles was investigated. The nanoparticles were either functionalized using octyl- or amino-terminated silanes, or used as received. The nanocomposites also contained 0.2 wt. % of Irganox 1010, a hindered phenolic stabilizer. The activity of the stabilizer in the samples was analyzed by Differential Scanning Calorimetry (assessment of Oxidation Induction Time (OIT)), and compared those obtained for the pristine polymers. The stabilizer was adsorbed to the untreated Al2O3 nanoparticles resulting in a significant reduction in OIT. The reduction increased with increasing total surface area of the particles. Surface silanization of the nanoparticles resulted in an increase in OIT, compared to the untreated particles. The activity of the stabilizer was evaluated by OIT after thermal ageing of the nanocomposites in hot-air oven at 90C up to 30 days. No surface oxidation was observed on any of the samples using reflection infrared spectroscopy. The ageing showed that the stabilizer was not irreversibly adsorbed to the particle surfaces, resulting in a gradual release with the ageing time. This resulted in a slower reduction in OIT as function of aging time for the nanocomposites, compared to the pristine polymer. In order for the nanocomposites to exhibit similar or higher OIT values after thermal ageing, compared to unfilled EBA, > 0.5 mg of stabilizer per m2 of octyl- or amine-coated Al2O3 nanoparticles was needed. The loss of stabilizer was controlled by the evaporation rate of the stabilizer from the surface of the samples to the surrounding air.

Keyword
poly(ethylene-co-butylacrylate), aluminum oxide, polymer nanocomposite, irganox 1010, antioxidant, stabilizer, OIT
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-28782 (URN)
Note
QS 20120328Available from: 2011-01-21 Created: 2011-01-21 Last updated: 2017-12-11Bibliographically approved

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