Abstract
Multilayer films consisting of a core layer of nylon 6 (PA6) sandwiched between two linear low density polyethylene (LLDPE) layers by using a tie layer were produced using a semi industrial cast film extrusion line. The core layer of the films was produced from neat PA6 and PA6/clay nanocomposite resins. The films were consequently uniaxially stretched in machine direction. The effect of stretching on crystalline structure, orientation as well as mechanical and barrier properties of the samples were investigated. Orientation of the films for both layers: polyethylene and nylon was assessed using FTIR (Fourier Transform Infrared Spectroscopy) and it was found that clay inclusion hindered orientation of the core nylon layer. Interaction of nylon molecules with clay influences the crystalline structure for nylon/clay nanocomposite film during the stretching as it hindered crystal transformation of γ to α phase. The effect of clay interaction on phase structure was also observed in DSC (Dynamic Scanning Calorimetry) results. Stretching improved barrier to oxygen for the samples. Oxygen transmission rate was reduced about 62.5% for the films having a nylon core and 50% for those with nylon/clay core when stretched to a draw ratio of 1.5 and remained nearly constant for higher draw ratios up to 3. Haze of the films was reduced with stretching; however the effect was more effective for the sample with neat nylon in the core layer when compared to the nylon/clay core one. Finally, it was observed that puncture resistance of the samples was improved significantly with stretching.
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