Improved fracture toughness and fatigue life of carbon fiber reinforced epoxy composite due to incorporation of rubber nanoparticles Nguyen Tien Phong • Mohamed H. Gabr • Le Hoai Anh • Vu Minh Duc • Andrea Betti • Kazuya Okubo • Bui Chuong • Toru Fujii Received: 1 January 2013 / Accepted: 23 April 2013 / Published online: 7 May 2013 Ó Springer Science+Business Media New York 2013 Abstract In this study, core–shell rubber (CSR) nano- particles with approximate particle size of 35 nm were used as a modifier for the epoxy polymer. The effects of various CSR contents in the epoxy matrix on mode I interlaminar fracture toughness, tensile strength, and fati- gue life of the carbon fabric reinforced epoxy (CF/EP) composites were investigated. The experimental results showed that the mode I interlaminar fracture toughness at crack initiation and propagation significantly improved by 71.21 and 58.47 %, respectively, when 8.0 wt% CSR was dispersed in the epoxy matrix. The fatigue life of the modified CF/EP composites at all of CSR contents dra- matically increased 75–100 times longer than that of the unmodified CF/EP composites at high cycle fatigue while tensile strength slightly increased by about 10 %. Field emission scanning electron microcopy (FESEM) observations of the fracture surfaces were conducted to explain failure mechanisms of CSR addition to the CF/EP composites. The evidences of the rubber nanoparticle debonding, plastic void growth, and microshear banding were credited for delaying the onset of matrix crack, and reducing the crack growth rate, as a result, attributed to increase in the mechanical properties of the CF/EP composites. Introduction Carbon fiber reinforced epoxy (CF/EP) composites, because of their high strength, light weight, and versatility, are being considered for use in the design of new advanced aircraft structural component [1–4]. Compared to metallic materials, the CF/EP composite possesses variety of advantageous properties, such as high strength to weight ratio, excellent corrosion resistance, and favorable fatigue tolerance. However, strength properties of the CF/EP composites are sensitive to failure modes, such as trans- verse cracking, longitudinal cracking, and delamination between adjacent layers due to intrinsic brittleness of epoxy matrix [5, 6]. The recent studies showed that the possibility of the most of failure modes of the fiber reinforced plastics (FRP) composites could be step by step controlled. Their mechanical performances would be dramatically enhanced by incorporating a small amount of nanoscale materials to the epoxy matrix [7, 8]. Takagaki et al. [9] found that with an addition of 0.3 wt% MFC to epoxy matrix, the fatigue life of carbon fabric composites significantly increased by 2,000 %. Davis et al. [3] reported that the tensile strength, stiffness, and tension–tension fatigue appreciably increased due to an addition of a little content of amine- N. T. Phong (&)  M. H. Gabr  A. Betti  K. Okubo  T. Fujii Department of Mechanical Engineering and Systems, Doshisha University, Kyotonabe, Kyoto 610-0394, Japan e-mail: phongnt42@yahoo.com; phongntmatescience@gmail.com N. T. Phong  V. M. Duc  B. Chuong Polymer Center, Hanoi University of Science and Technology, No 1, Dai Co Viet, Hanoi, Vietnam N. T. Phong  L. H. Anh Institute of Chemical and Biological Engineering, 80 Tran Quoc Hoan, Cau Giay, Hanoi, Vietnam M. H. Gabr Department of Mechanical Engineering, Sohag University, Sohag, Egypt A. Betti Department of Structural Engineering, Politecnico di Milan, Milan, Italy 123 J Mater Sci (2013) 48:6039–6047 DOI 10.1007/s10853-013-7400-z