Superior hygrothermal resistance and interfacial adhesion by ternary thermoplastic polymer blend matrix for carbon fiber composite

Carbon fiber reinforced thermoplastics (CFRTPs) with superior mechanical properties and hygrothermal resistance were fabricated using a strategically designed ternary polymer blend of polyamide 6 (PA6), polyethylene terephthalate (PET), and phenol novolac (PN). The polymer blend was designed to improve the hygrothermal stability of PA6 while retaining good adhesivity to carbon fiber. The miscible and immiscible components in the blend (PN and PET, respectively) have different contributions that act cooperatively to improve the hygrothermal resistance of PA6. The interfacial strength between the ternary polymer blend and carbon fiber is as high as that for PA6 because all components in the polymer matrix include polar functional groups. CFRTPs having the ternary blend as the polymer matrix exhibit superior stiffness under hygrothermal conditions than a conventional PA6-matrix CFRTP.