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The influence of silver myristate used as a precursor of silver nanoparticles on the direct current conductivity σ of epoxy polymer within the concentration range of ≤0.8 wt % was investigated. The value of direct current conductivity was determined on the basis of analysis of the frequency dependence of complex permittivity within the frequency range of 10-10 Hz. The temperature dependence of σ is composed of two regions. The dependence corresponds to the Vogel-Fulcher-Tammann empirical law σ = σexp{- DT /( T- T )} (where T is the Vogel temperature and D is the strength parameter) at temperatures higher than the glass transition temperature T . At the same time, T does not depend on the concentration of nanoparticles. The Arrhenius temperature dependence characterized by activation energy about 1.2 eV is observed at temperatures lower than T . The observed shape of the temperature dependence is related to the change in the mechanism of conductivity after 'freezing' of ionic mobility at temperatures lower than T . The value of σ is increased as the concentration of nanoparticles is raised within the temperature range of T > T . The obtained dependence of σ on silver myristate concentration is similar to the root one, indicating the absence of percolation within the studied range of concentrations. [ABSTRACT FROM AUTHOR]

The mechanical and thermomechanical properties of metal-containing epoxy composite films based on silver nanoparticles synthesized in situ are investigated. There is a nonmonotonic dependence of the mechanical properties on the concentration of silver myristate used as a precursor. It is found for the first time that the breaking strength and elastic modulus increase by a factor of 1.8-1.5 relative to those of the unmodified matrix at a small concentration of precursor nanoparticles (on the order of 0.1 wt %). DSC and thermomechanical studies reveal that the glass-transition temperature decreases slightly (by 5-6°C) as the precursor concentration is increased to 0.5 wt %, thereby suggesting a weak plasticization of the modified epoxy matrix. On the basis of the spectrophotometry data measured in the region of surface plasmon resonance of silver nanoparticles (420-425 nm) and SEM data, it is inferred that the in situ strengthening of an epoxy nanocomposite based on epoxy resin ED-20, triethylamine, and silver myristate is attained because silver nanoparticles smaller than 20 nm in size and having a narrow particle-size distribution are formed during curing. [ABSTRACT FROM AUTHOR]