Structural and Barrier Properties of Compatibilized PE/PA6 Multinanolayer Films

Abstract

The barrier performance and structural lightening of organic materials are increasingly desired and constitute a major challenge for manufacturers, particularly for transport and packaging. A promising technique which tends to emerge in recent years is that of multinanolayer coextrusion. The advantage is that it can produce multilayers made of thousands of very thin layers, leading to new properties due to crystalline morphology changes induced by confinement. This paper is focusing on the study of multinanolayered films with alternated polyethylene (PE), compatibilizer (PEgMA) and polyamide 6 (PA6) layers and made by a forced assembly coextrusion process equipped with layer multiplying elements (LME). PE/PA6 multilayer films consisting of 5 to 2049 layers (respectively 0 to 9 LME) were successfully obtained with well-organized multilayered structure. The evolution of the morphology and the microstructure of these two semi-crystalline polymers, when the thickness of each polymer layer decreases from micro-scale to nano-scale, was correlated to the water and gas transport properties of the PE/PA multilayers. The expected improvement of barrier properties was limited due to the on-edge orientation of crystals in very thin PE and PA6 layers. Despite this change of crystalline morphology, a slight improvement of the gas barrier properties was shown by comparing experimental results with permeabilities predicted on the basis of a serial model developed by considering a PE/PA6 interphase. This interphase observed by TEM images and the on-edge crystal orientation in multilayers were evidenced from mechanical properties showing an increase of the stiffness and the strength.

Recycling Polyethylene/Polyamide Multilayer Films with Poly(isoprene-g-Maleic Anhydride) Compatibilizer

“…PE/PA blends require a compatibilizing agent to achieve good interfacial adhesion between phases and improve mechanical, thermal, and permeability properties [ 7 ]. Some compatibilizers that have been used for low-density polyethylene/polyamide (LDPE/PA) blends are ethylene–acrylic acid copolymer [ 8 , 9 , 10 ], LDPE functionalized with acrylic acid [ 11 ], ethylene glycidyl methacrylate [ 12 ], ethylene vinyl acetate (EVA) [ 13 ], ethylene-methacrylic acid copolymer partially neutralized with sodium (Na-EMAA) [ 14 ], and maleic anhydride (MA) [ 1 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

Polymeric Membranes

“…Such materials have shown the formation of an oriented crystalline structure for well-chosen semi-crystalline polymers due to the confinement effect when the layer thickness decreases. For example, multi-nanolayer films of polyethylene (PE) and Polyamide (PA6) (PE/PA6), alternating PE and PA6 layers were investigated with the aim of understanding the morphological, structural, and barrier properties resulting in a nano-stratified structure [2]. Such structures demonstrated to be a relevant polymer pair for the industrial production of barrier films, as the crystalline morphology correlated with the barrier properties of the films in respect to different gases such as nitrogen (N 2 ), oxygen (O 2 ), carbon dioxide, and water.…”