Study on the performance of diglycidyl ether of bisphenol-A/hyperbranched aromatic polyester epoxy resin (HTME) system and their toughness mechanism

This paper reports on the use of liquid hyperbranched aromatic polyester epoxy resin (HTME) as an additive to an epoxy resin/amine system. Four kinds of different molecular weight and epoxy equivalent weight HTME as modifiers in the diglycidyl ether of bisphenol-A (DGEBA) amine systems are discussed in detail. It was shown that the content and molecular weight of HTME have important effect on the performance of the cured system, and the performance of the HTME/DGEBA blends has maximum with the increase of content and molecular weight or generation of HTME. The impact strength and fracture toughness of the cured system with 9wt.% second or three generation of HTME are almost 2.77 and 1.71 times, respectively, DGEBA performance; furthermore, the tensile and flexural strength can be enhanced about 17% and 20%, respectively. The glass transition temperature and Vicat temperature, however, are found to decrease to some extent. The scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and molecular simulation technology are used to study the situ reinforcing and toughening mechanism. The three-dimensional size and structure shape of HTME-2 are displayed by molecular simulation technology.