ABSTRACT
Epoxy networks are thermoset systems which are extensively used as composites matrix in automotive, aerospace, or electronic devices. They also find numerous applications as adhesives or coatings, which makes their overall application domain very large. This versatility is due to the fact that their properties are mainly governed by the polymer network structure, which can be tailored by an appropriate curing agent choice. They are likely to present high thermomechanical properties, low density, and good adhesion with other phases. Their main drawbacks are their brittleness when they are highly crosslinked,
their high tendency to uptake water, their polymerization shrinkage, and relatively high thermal expansion coefficient. Inorganic microscale fillers are dispersed in epoxies to reduce the polymerization shrinkage or to improve electrical conductivity or fire-retardant properties. However, the high filling rates needed to reach these objectives generally lead to the reductions in strength and toughness as well as increase in the materials density. To reduce their brittleness, core shell particles, liquid elastomers, or hyperbranched polymers can be incorporated in epoxy networks but in that case, the glass transition temperature is generally decreased, which results in a lowering of the thermomechanical stability of these materials.
