Shear-induced orientation of functional graphene oxide sheets in isotactic polypropylene

A shear-induced orientation extrusion technology was proposed to prepare high orientated functional graphene oxide sheets (FGs)/isotactic polypropylene (iPP) nanocomposites. Scanning electrical microscope and two-dimensional wide-angle X-ray diffraction techniques showed that FGs in iPP matrix were fully exfoliated, uniformly dispersed, and highly oriented along the flow direction. The crystallization behavior, the mechanical properties, the thermal stability, and the gas barrier properties of the composites with orientated FGs were evaluated by a differential scanning calorimetry, a tensile machine, a thermogravimetric analysis, and a gas permeability test, respectively. The results showed that the tensile strength, yield stress, Young's modulus, thermal stability, and barrier property of the iPP/FGs composites were improved on a whole by increasing the high orientation, uniform dispersion, and full exfoliation of FGs in the iPP matrix and the oriented crystallites of iPP as well as the high crystallinity.