Preparation and Properties Evaluation of an Epoxy Resin Toughened by a Combination of Reactive Polyester and Kaolin

Abstract

The present work investigates the effect of reactive polyester and kaolin on the mechanical and adhesive properties of brittle epoxy resin. The impact strength (IS), flexural strength and critical stress intensity factor (KC), as well as the adhesive strength under tensile and impact conditions, were evaluated as functions of the modifier content. The results obtained showed an improvement in the impact strength and flexural strength as well as adhesive strength under impact and tensile conditions due to kaolin and polyester addition. However, the flexural modulus decreased with the polyester and increased with the kaolin content. Hybrid compositions containing 30 wt.% of polyester and 30 wt.% of kaolin showed enhanced tensile adhesive strength as well as impact adhesive strength in comparison to the virgin epoxy resin, exhibiting a synergic effect. SEM micrographs confirmed the presence of a regular and homogeneous stratified structure with particles embedded in the polymer matrix, explaining the improvement of mechanical properties.