Improvement of mechanical properties of epoxy/anhydride coatings using sepiolite and a hyperbranched polyster

Epoxy resins are one of the most successful thermosetting materials when it comes to industrial application, and their uses embraces adhesives, coatings, encapsulation of electronic components and matrices of composite materials among others. The explanation to the extended usage of such materials can be found in the excellent properties they present in terms of chemical and thermal stability, heat distortion, high stiffness and versatility among others.1 However, they present also some drawbacks that limit their range of applications. One of the most significant is their poor impact resistance, since due to their high crosslinking density epoxy resins are inherently brittle coatings.\nIn order to overcome this lack on toughness, the use of nanofillers have attracted great interest, both in academic and industrial fields, because they often exhibit dramatic improvements in mechanical properties of polymer matrix even at very low loadings.2\nAnother strategy recently adopted is the use of hyperbranched polymers (HBP) as chemical modifiers of epoxy resins.3,4 If the HBP is homogeneously dispersed in the matrix it introduces flexibility to the network resulting in an improvement in toughness. The particularity of this strategy is the fact that it is accomplished without compromising other properties of the material such as its Tg or hardness, and also without dramatically increasing the viscosity of the curing mixture.\nHere we present the combination of the two strategies in order to improve toughness. The influence on the curing process and in the final thermomechanical properties of both additives has been studied and finally some mechanical properties have been determined. The results have been correlated with the morphology of the materials.