Polymeric films with coextruded multilayer architectures of alternating layers of particulate filled nanocomposites were investigated for improvements in gas/fire barrier properties and electrical conductivity. Gas transport models demonstrate a need for higher aspect ratio platelets for maximum barrier enhancement. Therefore, high aspect ratio graphene nanoplatelets (xGnP®) melt-blended into linear low density polyethylene (LLDPE) layers were alternated with layers of un-filled low density polyethylene (LDPE) to produce films with properties typical of high loading nanocomposites. Improvements in material properties are possible through a boundary movement phenomenon that occurs when a system of alternating layers of miscible polymers with highly different mobilities are allowed to interdiffuse in the melt. The greater mobility of the more linear LLDPE chains as compared to the more branched LDPE chains cause a layer movement in the direction of the more slowly diffusing LDPE chains. The high aspect ratio platelets remain in the shrunken LLDPE layers resulting in an increase in concentration in the nanocomposite layers. The property improvements in the nanocomposite layers are reflected in the overall film properties. The effects of particle size, loading, and melt processing conditions on composite morphology and properties were analyzed. Multilayer layer thicknesses and annealing conditions of the films were also studied. Bulk composites were utilized for comparison with the multilayer films through various stages of particle concentration where the annealed multilayer systems demonstrated properties indicative of high loading composites.

Polyethylene-based composites containing graphene platelets: Enhanced barrier and electrical properties via multilayer coextrusion and interdiffusion

249th National Meeting (2015)

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