Fatigue life improvement of CFRP due to hybrid modification of polymer matrix with cellulose nano fibers and nano rubber particles

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Epoxy matrix of CFRP was physically modified with different types of cellulose nano fibers (CNF) including bacterial cellulose, whose weight content was about 0.3-0.8wt%. Any types of CNF incredibly extend the fatigue life of CFRP in comparison with the unmodified one. An excessive amount of CNF decreases the life extension effect.When CNF were simultaneously mixed with nano rubber particles, the tensile strength of modified CFRP appreciably increased without scarifying other properties due to a hybrid effect. More fatigue life extension is expected due to an appropriate hybrid modification. 50nm (in diameter) PVA, 500nm glass and 700nm PET fibers were also tested instead of CNF. Those fibers extended the fatigue life of CFRP as well in spite of difference in their mechanical performance. Thin (smaller than 1 μm) fibers are useful as a matrix modifier of CFRP. When an appropriate content of CNF was mixed into epoxy matrix, less fiber debonding occurred. Other resin matrices such as vinylester can be modified with CNF for fatigue life extension.