Epoxy resin toughening for aplication in structural composites

Abstract

There are two main features responsible for the aeronautical industry interest in structural composites. The first is the possibility of integrating various structural components, reducing the number of rivets and the total number of aircraft parts. The second is the possibility of positioning the reinforcement, typically carbon fibers, in direction of greatest stress. These features allow designing larger and more comfortable cabins, reducing fuel use by decreasing of the engines power. Since the aircraft's weight was reduced, the power needed to propel it will also be lower.One of the main reasons for the aviation industry distrust in implement composites in structural functions is in its complex and poorly studied fatigue behavior, which raises doubts about the best time to replace the component, the security that it offers, as well as the mode failure, which varies with the type of fabric used in the component manufacture and type of processing.The delamination has been another constant barrier to the application of composites as structural material. Despite having high mechanical strength and fatigue, delamination may occur before the component reaches 10 ³ cycles, reducing the reliability of the aviation industry in this material. It is known that the delamination may be attributed to factors such as poor interfacial adhesion and low toughness of polymer matrices.The purpose of this study is to promote the toughening of Cycom 890 RTM epoxy resin through the addition of hyper-branched polyester chain as thoughening agent. Thus we intend to increase the capacity of the polymer to release energy through relaxation of the polymer chains avoiding premature rupture when this act as matrix in structural composites. The modified polymer will be evaluated by dynamic mechanical analysis and fracture toughness.With this will be possible, in the future, propose a modification in epoxy resins used for produce structural composites by RTM for aircraft industry by the Fatigue and Aeronautic Materials Research Group. (AU)