Synthesis, Characterisation, Thermal And Electrical Behaviour Of Copper And Copper Sulphide-Epoxy Nanocomposites
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Date
2011-08
Authors
Mohd Hirmizi, Nor Hashila
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Copper (Cu) and copper sulphide (CuS) nanoparticles were synthesised in an
aqueous phase and subsequently transferred into the organic phase containing epoxy
via phase transfer technique. The UV-vis absorption spectra confirmed the existence
of Cu and CuS. Incorporation of diglycidyl ether of bisphenol A (DGEBA) into the
respective organosols and upon solvent removal afforded Cu- and CuS-epoxy
nanocomposites. These composites were cured using 4,4’-methyelene-dianiline
(MDA). In the case of Cu-epoxy, the highest particle transfer efficiency was at ≈ 97.2%
when the samples were prepared with 5 mL isopropanol (IPA). IPA also exerts
influence on the average particle size. At higher percentage of epoxy, the particle
sizes, size distributions as well as the particle self assembly were decreased.
Moreover, the size of the particles was smaller as compared to in the hydrosol. For
CuS, period of stirring affects the shape of CuS particles. The average particle size,
size distribution and dispersion vary upon particle transfer into the organic phase as
well as dependent on the types of organic solvent used. The presence of epoxy also
enhanced the CuS particle stabilisation and exerts better particle size control. For the
Cu-epoxy nanocomposites, the composites exhibit lower thermal stability as compared
to cured epoxy due to accelerating effect on decomposition of the composites by the
nano-sized conducting filler. However, addition of Cu filler increased the glass
transition temperature (Tg) values of the composites from 114.9°C to 122.7°C as the
result of decrement in free volume and the polymer chains mobility. Furthermore, it
also decreased the coefficient of thermal expansion (CTE) values. On the contrary, for
the CuS-epoxy, it is observed that the extent of curing has been disrupted by the
addition of CuS particles. Addition of CuS filler decreased the Tg and CTE values but
maintained the thermal stability of CuS-epoxy nanocomposites. This is attributed to the
probable interactions between CuS particles and the epoxides. Addition of both fillers
into epoxy increased the electrical conductivity of the respective composites. With the
volume fraction of the fillers < 10 vol.%, the electrical conductivity values were within
the range of 10-2 S cm-1, the composites obtained in this work were categorised as the
anisotropic conductive adhesive (ACA)-type.
Description
Keywords
Electrical Behaviour , Copper And Copper Sulphide-Epoxy