Effects of Epoxy/Filler Interface on Properties of Nano- or Micro-composites

Abstract

This paper focuses on the effects of the interface between epoxy resin and nano-or micro-scale silica filler. Experiments were carried out on epoxy resin containing nano-or micro-scale silica fillers (nano-composite or micro-composite) to investigate the effects of the epoxy/filler interface on the properties of water absorption, electrical insulation and fracture toughness. The results indicated that epoxy/silica filler interface has an impact on the properties of the nano-and micro-composites. Nano-composites were shown to have higher water absorption than micro-composites because water accumulated over a larger interface area. Moreover, the nano-composites with interfaces treated with a silane coupling agent showed insulation breakdown properties and fracture toughness superior to those of the base epoxy resin and the micro-composites. The chemical bonding by the silane coupling agent at the epoxy/nano-scale silica filler interface played a more important role in water absorption and insulation breakdown properties than for the micro-scale silica filler. The filler size reduction to nano-scale needs appropriate interface treatment because of its tremendously large interface area. In addition, belt-shaped area models demonstrated the improvement of insulation breakdown properties and fracture toughness from the viewpoint of encountering frequency between electrical treeing or initial cracking and fillers. It is assumed that an increase in encountering frequency prevents treeing or cracking from propagating efficiently and thus improves insulation breakdown properties and fracture toughness in the nano-composite.

Electrical Treeing in Polymer Nanocomposites

“…It was found that addition of ZnO particles into epoxy resin improves the resistance to electrical tree growth and also increases the time to breakdown. It has also been reported that epoxy/silica nanocomposites exhibit longer treeing life time than pure epoxy [5]. Another work reports that epoxy nanomicro particle mixed composite exhibit increased treeing life time as compared to conventional micron size particle filled as well as pure epoxy [6].…”

Effect of pre-treatment of nanofillers on the dielectric properties of epoxy nanocomposites

“…Recent researches also indicated that the interface area between nano size fillers and the base polymer materials is one of the determining factors for the dielectric properties of the nanocomposites. It has been shown that such poor filler dispersion has a negative effect on the performance of composites [22]. To improve the nano size filler dispersion, the surface treatment method has been introduced.…”

Probing of dielectric properties of high density poly-ethylene/calcium carbonate (HDPE/CaCO3) nano-micro composite

“…In this context, several techniques such as using compatibilizers and coupling agents, high shear force mixing, solution mixing etc. have been adopted to get better dispersion results (Celebrese et al, 2011;Nelson, 2010;Imai et al, 2006;Working Group, 2011). Nano-particles have much higher interfacial area per unit volume and in addition the interface between the particle and polymer is thought to have a finite thickness in which the properties of the polymer differ from the original matrix .…”

“…In such systems the total interfacial volume can be very large and may control the dielectric response of the system (Lewis, 1994). However, there have been conflicting reports in the literature regarding the effect of nano-micro particles on the dielectric properties of polymer composites, since they have been shown to inflict increase and decrease in dielectric properties (Imai et al, 2006;Krivida et al, 2012;Singha and Thomas, 2008). While variations are to be expected in different systems, the effect of processing can also be a determining factor in the final properties.…”