The effects of HNO3

Carbon fibers (CFs) were surface treated using nitric acid (HNO3). Afterward, polyamide 6/acrylonitrile–butadiene–styrene (PA6/ABS)-based hybrid nanocomposites containing 10 wt% of HNO3-treated short CFs and 0, 2, 5, and 8 wt% of calcium carbonate (CaCO3) nanoparticles were produced using a counter-rotating twin-screw extruder and injection molding machine. Scanning electron microscopic observations showed the formation of strong interaction between surface-treated CFs and polymer matrix. Dynamic mechanical thermal (DMTA) and thermoanalytical assessments were carried out. DMTA results indicated considerable improvements of storage modulus and viscose damping, in a wide range of temperature, by incorporating surface-treated CFs and CaCO3 nanoparticles. The glass transition temperatures of composites were noticeably greater than that of neat polymer because of the restriction effects of the fibers and nanoparticles on polymer chain mobility. Surface-treated CF and CaCO3 inclusions considerably elevated the heat of fusion and crystallinity. Results of thermogravimetric analyses indicated noticeable higher thermal stability against decomposition for composites as compared to the neat polymer. The adhesion of PA6/ABS polymer to surface-treated CFs and the presence of nanoparticles in polymer–fiber interphase were considered to be the key factors in determining the properties of composites