Alumina/epoxy nanocomposites

Jin and Park processed the Al O -epoxy nanocomposites by hot curing technique [69]. Zheng et al. prepared the SiO -epoxy nanocomposites by mixing the nanoparticles in epoxy matrix at 120°C [4]. Similarly, SiO -based thermoset polyester nanocomposites are prepared by mechanical mixing followed by ultrasonication [72]. Alumina-epoxy nanocomposites are also processed in-situ by reducing the size of alumina particles from micrometer range to nanometer range with the assistance of mechanical vibrator [73]. 

In poorly bonded NT- Al O /epoxy composites, particles are clearly visible and the crack seems to have propagated aroimd their equator. Ihe fracture surface of nanocomposites consists of hemispherical holes (A), top surface of the debonded particles (B) and particles covered by epoxy matrix (C). The crack may propagate above or below the poles of the particles through the matrix. Interfacial debonding seen in the mirror zone is not seen in the hackle zone for treated alumina-epoxy nanocomposites. Another toughening mechanism noticed in the hackle zone is particle pullout, which is seen in both NT- Al O /epoxy nanocomposites and APTES-Al Oj/epoxy nanocomposites, whereas micro-cracking is noticed only in APTES-Al Oj/epoxy nanocomposites. 

In a similar manner, alumina-epoxy (DGEBA) nanocomposites with definite weight fraction (7,12,16 wt%) are processed via room temperature... 

Figure 9.22 shows the X-ray diffraction pattern of as-received alumina, epoxy and epoxy-alumina nanocomposites [73]. The as-received micron-size alumina has characteristic peaks at 14.5°, 28.1°, 38.3°, 48.9° and 55.1°. Epoxy is identified by its characteristic peaks at 5° and 17.8°. However, for nanocomposites, peaks are present at 28.1°, 38.3° and 48.9°. The intensity of diffraction peak of alumina decreases and its width increases in the nanocomposite samples, which is attributed to the decrease in size of the alumina particles from micron to nano-size. 

Dynamic mechanical analysis is done by researchers to analyze the viscoelastic properties of polymer nanocomposites [3,73,80]. Omrani et al. studied the influence of nano-alumina on the viscoelastic properties of epoxy in... 

Polymer nanocomposites were processed using non-treated alumina (NT-Al Oj) and aminopropyltriethoxysilane treated alumina (APTES-Al Oj) in epoxy matrix [97-98]. The tensile fracture surface is evaluated for analyzing the strengthening and toughening mechanisms. The tensile fracture surfaces of neat epoxy and nanocomposites containing 10 phr-NT- Al O and 10 phr-APTES- Al O are shown in Figure 9.34. 

Fig. 9.3 Variation in the real part of the relative permittivity of nanocomposite systems, as a function of volume fraction of alumina (AI2O3) and magnesium oxide (MgO) nanoparticles in an epoxy resin matrix data from Andritsch (2010)...

Maity P, Gupta N, Parameswaran V, Basu S (2010) On the size and dielectric properties of the interphase in epoxy-alumina nanocomposite. IEEE Trans Diel Electr Insul 17 1665-1675 Miwa Y, Drews AR, Schlick S (2008) Unique structure and dynamics of poly(ethylene oxide) in layered silicate nanocomposites accelerated segmental mobility revealed by simulating ESR spectra of spin-labels, XRD, FTIR, and DSC. Macromolecules 41 4701-4708 Morshuis PHF, Kreuger FH, Leufkens PP (1988) The effect of different types of inclusions on PE cable life. IEEE Trans Electr Insul 23 1051-1055... 

Miyagawa, H., Mohanty, A., Drzal, L.T., Misra, M., 2004a. Effect of clay and alumina-nanowhisker reinforcements on the mechanical properties of nanocomposites from biobased epoxy a comparative study. Industrial Engineering Chemistry Research 43, 7001-7009. 

The depression of the final hmiting fictive temperatures of polycyanurate networks under nanoscale constraint observed in the current study corroborates that the BMDC monomer does penetrate into the nanopores instead of acting as fillers, because the glass transition temperature of the polymer is not expected to be affected when the particles are in micron size as seen in the nanocomposites of epoxy/silica [13] and PMMA/alumina... 

---