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In situ synthesis of epoxy nanocomposites with hierarchical surface-modified SiO2 clusters

Abstract

Polymer nanocomposites are often produced using in situ approaches where an inorganic filler (as the dispersed phase) is synthesized directly in an organic matrix. Such an approach generally leads to improved dispersion and reduced agglomeration of the filler material. Epoxy-based nanocomposites have demonstrated promising properties for application as high-voltage insulation materials. In this work, a sol–gel based method has been adapted to synthesize surface-functionalized SiO2 in situ in epoxy. The synthesized SiO2 moieties were dispersed in clusters of 10–80 nm, and formed chemical bonds with the epoxy monomers via a silane coupling agent. Raman spectra show the formation of four-membered D1 rings, which may be part of a cage-like structure similar to that of polyhedral oligomeric silsesquioxanes (POSS). SAXS measurements indicate that the SiO2 clusters consist of a hierarchical structure with an increasing fractal dimension with increasing SiO2 content. The nanocomposites displayed improved thermal stability, while the glass transition behavior varied depending on the structure and content of the SiO2 moieties. While the relative permittivity showed no significant changes from that of pure epoxy, the onset of the dielectric relaxation changed with the SiO2 structure and content, similar to the behavior observed for the glass transition.

Category

Academic article

Client

  • Research Council of Norway (RCN) / 197405
  • Research Council of Norway (RCN) / 259866

Language

English

Author(s)

Affiliation

  • Norwegian University of Science and Technology
  • SINTEF Energy Research / Elkraftteknologi

Year

2020

Published in

Journal of Sol-Gel Science and Technology

ISSN

0928-0707

Publisher

Springer

Volume

95

Page(s)

783 - 794

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