Infrared spectroscopic characterization of polymer and clay platelet orientation in blown films based on polypropylene-clay nanocomposite

The "tilted film" transmission infrared spectroscopy method was used to characterize the biaxial orientation in a set of blown films containing polypropylene (PP), layered silicate nano-reinforcement, and two different compatibilizing agents based on maleic-anhydride-grafted PP. Both interactive spectral subtraction and peak fitting were used to determine trichroic ratios. The biaxial orientation of the polymer chains could be clearly quantified according to well-established relationships for PP. in addition, the clay platelet orientation could be determined from the trichroism of the Si-O stretching bands around 1100 - 1000 cm(-1). The clay orientation was found to be quite high (Hermans orientation function around +0.8) and was not significantly affected by the presence of compatibilizing agent.