Coextrusion and biaxial orientation of multi‐microlayer films

In this study, the multi‐microlayer films (MMFs) prepared by the coextrusion of the corresponding polymers using a feed block design are reported. The alternating layers of the linear low‐density poly(ethylene) and ethylene vinyl alcohol polymers are used to produce the 3‐layered and 100‐layered MMFs with the total thickness of around 640 μm. The MMFs are going through biaxial orientation and heat treatment which can change the morphologies and physical properties and reduce the thickness of the films to several micrometers. The differences in crystallinity, melting temperature, interface physical properties, tensile strength, and water vapor transmission rate of the MMFs are fully investigated. The intermolecular interaction of the 100‐layered MMFs is much higher than that of the 3‐layered MMFs possibly due to the tightly bonded layers which lead to the disappearance of the interface layers following by orientation. The MMFs are successfully prepared by coextrusion following by biaxial orientation and heat treatment of two or more different kinds of polymers with very different intrinsic properties. This MMFs exhibit excellent compatibility, mechanical property and water resistance characteristics which have potential uses in the composite materials for food and electronic packaging applications.