Quantitative characterization of the interface between bamboo fiber and polypropylene with pull-out test and nanomechanical imaging

Single-fiber pull-out test was adopted to quantitatively assess the respective contribution of physical and chemical interactions to the interfacial bonding between bamboo fiber (BF) and polypropylene (PP), which was regulated with different concentrations of maleated polypropylene (MAPP) and silane (KH-550) coupling agents. Meanwhile, a new AFM-based nanomechanical imaging technique, namely the peakforce quantitative nanomechanics (PQNM), was used for mechanically imaging the interface of the resulting composites. The interfacial shear strength (IFSS) was found to be positively correlated to the concentration of MAPP and silane, but with less significance for the latter. Furthermore, the respective contribution of physical and chemical bondings to the total IFSS can be approximately quantified. PQNM was capable of mechanically visualizing the different cell wall layers of BFs and their interface with PP matrix, but failed to discriminate the so-called interphase layer that is normally characterized with dozens of nanometers in thickness.