Fundamentals of Polyethylene Composites for HVDC Cable Insulation – Interfaces and Charge Carriers

التفاصيل البيبلوغرافية
العنوان:	Fundamentals of Polyethylene Composites for HVDC Cable Insulation – Interfaces and Charge Carriers
بيانات النشر:	KTH, Polymera material Stockholm 2020
تفاصيل مُضافة:	Karlsson, Mattias E.
نوع الوثيقة:	Electronic Resource
مستخلص:	Power transmission over long distances by using high voltage direct current (HVDC) cables is important for the transition from fossil energy to using renewable energy sources, e.g. wind, solar and water. Higher operating voltages enable longer transmission lines but better insulation materials with a much lower conductivity than today´s crosslinked polyethylene (PE) are required to reach the goal of 1 MV by 2030. Nanocomposites consisting of small fractions of metal oxide nanoparticles in PE are promising insulation materials, showing ca. 100 times lower conductivity. The reasons for the better insulating properties are however not fully understood. The properties of PE and inorganic nanoparticles were studied in this project to evaluate the influence of different material parameters on the conductivity of the cable insulation material. For pristine PE, the polymer morphology and oxidation were found to have a significant impact on the conductivity. For PE nanocomposites, the particle/polymer interface was shown to adsorb polar molecules, which are present in PE cable insulation. A suggested hypothesis is that the adsorption on particle surfaces results in cleaning of the bulk polymer from impurities, which in turn contributes to decreased nanocomposite conductivity. Since the particle interface is believed to be decisive for the nanocomposite properties, the role of particle terminations was investigated in detail. Oxygen dominated particle terminations resulted in 2 times higher composite conductivity than with zinc dominated surfaces, while fully oxygen covered surfaces showed 10 times higher conductivity. Composite systems with micro-sized particles allowed for evaluating parameters independently, which is not possible for nanocomposites. Terminations of ‘PE-like’ hydrocarbon chains lowered the conductivity and these trends could also be transferred to similar zinc oxide nanocomposite systems. Distribution av elektrisk energi över långa avstånd genom att använda högspänd likström (HVDC) blir allt viktigare för att ställa om till en förnyelsebar energiproduktion (t.ex. solkraft, vindkraft och vattenkraft). Med ökad driftspänning kan längre kabelsystem användas på grund av minskade förluster, men detta ställer högre krav på isoleringsmaterialet. Nya koncept med bättre isolerande egenskaper (t.ex. lägre konduktivitet) än dagens tvärbundna polyeten (PE) måste utvecklas för att kunna uppnå målet med en driftspänning på 1 MV till 2030. Kompositer bestående av nanopartiklar i PE är ett lovande alternativ som är ca. 100 gånger mer isolerande än PE men kunskapen om varför kompositer uppvisar bättre isolerande egenskaper är inte komplett. Egenskaper hos PE och inorganiska nanopartiklar studeras i detta projekt för att utvärdera vilken betydelse olika parametrar har för DC konduktiviteten. För ren PE så påverkade polymerens morfologi och oxidation konduktiviteten signifikant. För nanokompositer är gränsytan mellan partikel och polymer viktig för kompositens egenskaper och det visades att polära molekyler som finns i kabelisolering av PE adsorberades på partikelytorna. Det föreslogs att adsorptionen bidrar till en renare polymer i kompositerna, vilket i sin tur minskar konduktiviteten. Termineringar på zinkoxidpartiklar undersöktes i detalj och partiklar med en majoritet av syre på ytan ökade kompositens konduktivitet 2 gånger jämfört med dominerande termineringar av zink. Ytor helt täckta av syre ökade konduktiviteten 10 gånger. Påverkan av funktionaliteten på partikelytan kunde studeras oberoende av andra parametrar genom att använda större mikropartiklar, vilket inte är möjligt för nanopartiklar. Slutsatsen att partikelytor med kolväten som liknar PE sänkte konduktiviteten jämfört med syredominerande ytor kunde även bekräftas för kompositer med nanopartiklar. QC 2020-05-25
مصطلحات الفهرس:	polyethylene, nanocomposites, HVDC, conductivity, metal oxide, nanoparticles, surface functionality, polyeten, nanokompositer, konduktivitet, metalloxider, nanopartiklar, ytfunktionalitet, Composite Science and Engineering, Kompositmaterial och -teknik, Textile, Rubber and Polymeric Materials, Textil-, gummi- och polymermaterial, Nano Technology, Nanoteknik, Doctoral thesis, comprehensive summary, info:eu-repo/semantics/doctoralThesis, text
URL:	http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-273541 TRITA-CBH-FOU ; 2020:27
الإتاحة:	Open access content. Open access content info:eu-repo/semantics/openAccess
ملاحظة:	application/pdf English
أرقام أخرى:	UPE oai:DiVA.org:kth-273541 0000-0001-5478-1840 urn:isbn:978-91-7873-547-1 1233717757
المصدر المساهم:	UPPSALA UNIV LIBR From OAIster®, provided by the OCLC Cooperative.
رقم الأكسشن:	edsoai.on1233717757
قاعدة البيانات:	OAIster

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