Formation and the structure of freeze-dried MgO nanoparticle foams and their electrical behaviour in polyethylene
2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 14, 7523-7534 p.Article in journal (Refereed) Published
Electrically insulating low-density polyethylene (LDPE) nanocomposites based on dispersed MgO nanoparticle foams are reported. The foams were obtained via freeze-drying aqueous suspensions of precipitated ca. 40 nm wide and 10 nm thick Mg(OH)(2) nanoparticles and dewatering (calcining) at 400 degrees C, resulting in a 25 times more voluminous powder compared to conventionally dried nanoparticles. This powder handling prior to extrusion melt-processing greatly facilitated the nanocomposite preparation since no particle grinding was necessary. Large quantities of particles were prepared (>5 g), and the nanoparticle foams showed improved dispersion in the LDPE matrix with 70% smaller aggregate sizes compared to the conventionally dried and ground nanopowders. The nature of the nanoparticle foams was evaluated in terms of their dispersion on Si-wafers using ultrasonication as a dispersing aid, which showed to be detrimental for the nanoparticle separation into solitary particles and induced severe aggregation of the calcined nanoparticles. The grind-free MgO nanoparticles/LDPE-composite was evaluated by electrical measurement. The prepared composite showed an initial ca. 1.5 orders of magnitude lower charging current at 10(2) s, and a 4.2 times lower charging current after 16 hours compared to unfilled LDPE. The results open a way for improved insulation to be implemented in the future high-voltage cable system and present a new promising nanoparticle powder handling technique that can be used on a large scale.
Place, publisher, year, edition, pages
2015. Vol. 3, no 14, 7523-7534 p.
Chemical Engineering Physical Sciences
IdentifiersURN: urn:nbn:se:kth:diva-165239DOI: 10.1039/c4ta06362gISI: 000351845400042ScopusID: 2-s2.0-84925651646OAI: oai:DiVA.org:kth-165239DiVA: diva2:809718
QC 201505052015-05-052015-04-242016-10-06Bibliographically approved