Polyester containing isocyanate groups—Modified epoxy resin: Rheological, dynamic‐mechanical, and impact properties

Abstract

Low molar mass hydroxyl‐terminated polyester was functionalized with isocyanate groups (NCO) and used to improve the impact resistance of epoxy resin (ER) cured with triethylene tetramine (TETA). The effect of polyester‐based modifiers (with or without NCO groups) on the curing rate of epoxy/TETA system was investigated by rheological techniques. It was found that the functionalized polyester decreased the gel time, indicating an accelerating effect of the curing process. In addition, significant improvement in impact resistance of the epoxy network was achieved, with low detrimental effect on the glass transition temperature and stiffness. The modified epoxy systems did not present phase‐separated morphology discernible by scanning electron microscopy, even after the curing process. The glass transition temperature of the epoxy networks was also investigated by dynamic‐mechanical analysis. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

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

“…The scanning electron microscope results showed rough morphology and plastic deformation in the DGEBA/polyester blends. In another work, Soares et al modified epoxy resin cured with triethylene tetramine using hydroxyl-terminated polyester containing isocyanate groups 22 . Their results showed that the added reactive polyester decreased the gel time and improved the impact strength of the epoxy network, with little detrimental effect on the glass transition temperature and stiffness.…”

“…Various studies have been carried out on the effects of solid particles such as kaolin and liquid polyesters on the mechanical properties of epoxy resins 4,[19][20][21][22] . Kaolin was used by Fellahi et al 4 as a modifier for the diglycidyl ether of bisphenol A with polyamino-imidazoline as a curing agent.…”