Rheological, Mechanical and Barrier Properties of Multilayer Nylon/Clay Nanocomposite Film

Multilayer films consisting of a core layer of nylon 6 sandwiched between two linear low-density polyethylene layers were produced using a semi-industrial cast film extrusion line. The core film was produced at different draw ratios from neat nylon and nylon/clay nanocomposite resins. The objective was to assess the replacement of neat nylon with a nylon/clay nanocomposite for the core layer of a multilayer film. Rheological experiments were carried out to characterize the resins and study the aspects of the extrusion process. It was observed that clay platelets could restrict chain mobility and intensify thermal degradation in melt processing; however, that could be balanced to some degree with a polycondensation reaction that increases the chain length and molecular weight. The crystalline structure of the films was examined by X-ray, differential scanning calorimetry, and Fourier transform infrared measurements. The clay inclusion favored the -phase crystalline phase, which showed a lower melting point. Increasing the draw ratio from 6.5 to 13 during the extrusion process did not have a significant impact on the orientation of either nylon or nylon/clay in the core layer. The physical and mechanical properties of the films were studied and discussed. Replacement of nylon with the nylon/clay nanocomposite in the core layer did not yield a notable improvement in the tensile properties of multilayer films. However, the oxygen barrier property was improved by 48% when the nylon/clay nanocomposite was used as the core layer. The haze property was not affected by either changing the draw ratio or using the nanocomposite instead of nylon. (c) 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: E53E64, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20270