Carbon fiber-reinforced composites using an epoxy resin matrix modified with reactive liquid rubber and silica nanoparticles

Carbon fiber-reinforced composites are gaining importance and are about to play a very prominent role in automotive applications. In structural applications mainly epoxy resins are used as matrix materials. The properties of epoxy resins and laminates made thereof can be improved by tougheners like reactive liquid rubbers. Further improvements can be achieved by adding surface-modified silica nanoparticles, with 20 nm in size and a very narrow particle size distribution. In this study carbon fiber-reinforced laminates made from epoxy resins modified with reactive liquid rubber and silica nanoparticles have been prepared and investigated. A very fast amine cure of 15 min has been chosen to match industrial needs. Mechanical properties for bulk resins and laminates are compared and the mechanisms responsible for the property improvements are discussed. Structure property relationships between the neat resin fracture toughness and the interlaminar GIc and GIIc of the reactive liquid rubber and silica nanoparticles modified resins were established. Tough laminates could be prepared. However, CAI performance of the hybrid laminates was slightly inferior as compared to the rubber-toughened laminates, most probably due to agglomerates of nanoparticles found in the cured resin systems. The reason for the nanoparticle aggregation was detected and their influence on laminate performance discussed.