Recent coextruded nano-layer structural film advances have been made and grouped into 3 basic structures including both nano-layers and micro-layers. Blown films have been made from each which were later oriented into shrink films and characterized. Both Nylon 6/66 and EVOH O2 barrier films as well as all polyethylene films were included. Film samples containing from 25 micro- layers to 77 nano-layers were included in this structural array. The results from this study were surprising. Nano-layers increased the orientation ratios from 5x5 to 7x7 so that thinner yet tougher shrink films were made with increased tear resistance than that of the 3 layer control. Further, more nano-layers made orientation still easier. These observations prompted the development of a theoretical model for the Layer Sequence Repeater (LSR) based on parallel melt flow. And finally, a theory about the crystallinity anomalies seen with nano-layer EVOH and N6/66 is presented using DSC measurements.
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