Understanding the interfacial and agglomeration impact in epoxy nanocomposites on its electrical and mechanical properties

In the present study, epoxy nanocomposites are prepared with magnesium oxide (MgO) and aluminum nitride (AlN) as filler materials, and their surface potential decay and charge trap characteristics are studied. The reduced decay rate with deep traps formation is observed with an increase in wt% of nanofiller, above certain optimized wt%. The mean lifetime for surface potential decay under positive DC voltage is three times or more for neat epoxy compared to the specimens filled with 1 and 3 wt% MgO filler and almost two times for the specimen filled with 1wt% AlN. Volume fraction and Young's modulus of interphase and agglomeration phases in the polymer nanocomposite are calculated with respect to filler wt% by using the proposed micromechanical models. The calculated thickness of interphase R-i decreased with respect to filler wt% for both MgO- and AlN-filled epoxy nanocomposites. The R-i value for 1wt% MgO-filled specimen is almost three times higher compared to specimen filled with 5 wt% filler. The calculated volume fraction of interphase phi(i) for specimen filled with 3 wt% MgO almost ten times higher. The calculated volume fraction of the agglomerations for specimens filled with 5 wt% MgO and AlN is almost same. The Young's modulus of the epoxy nanocomposites and the calculated values based on proposed model showed good correlation. From the modeling study, it could be realized that interphase thickness, radius of the nanoparticle and agglomerated particle size have influence on Young's modulus of the nanocomposites. It is observed that Young's modulus of the interface is higher than that of Young's modulus formed due to agglomeration.