Epoxy resin was modified using phenyl diglycidyl ether (PGE), xylene and kaolin. The impact strength (IS), critical stress intensity factor (K), flexural strength and glass transition temperature (Tg) were evaluated as functions of the modifier content. It was found that the addition of diluents led to a significant reduction of both viscosity and Tg. A three-fold increase of IS was obtained with the addition of 2.5% PGE. Moreover, the addition of 15% PGE resulted in about 145% enhancement of the KC parameter. However, the addition of xylene had no significant effect on these properties. Furthermore, the addition of 10% kaolin to epoxy resin gave compositions with the highest fracture toughness. Maximum KC values were obtained with epoxy hybrid compositions containing 10% kaolin and 2.5% PGE and 10% kaolin and 5% PGE respectively. All tested compositions had higher energy at break than nonmodified epoxy resin. SEM micrographs of fractured surfaces of modified epoxy compositions revealed the presence of plastic deformations, which can be considered as the main source of the mechanical properties enhancement.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.