Structure and oxygen‐barrier properties of (linear low‐density polyethylene/ethylene–vinyl alcohol copolymer)/linear low‐density polyethylene composite films prepared by microlayer coextrusion

Abstract

Ethylene-vinyl alcohol copolymer (EVOH) and linear low-density polyethylene (LLDPE) blends with 5% LLDPE grafted with 1% maleic anhydride (MAH; EVOH/LLDPE/LLDPE-g-MAH), created to increase the interfacial compatibility, were coextruded with pure LLDPE through the microlayer coextrusion technology. The phase morphology and gas-barrier properties of the alternating-layered (EVOH/LLDPE/LLDPE-g-MAH)/LLDPE composites were studied by scanning electron microscopy observation and oxygen permeation coefficient measurement. The experimental results show that the EVOH/LLDPE/LLDPE-g-MAH and LLDPE layers were parallel to each other, and the continuity of each layer was clearly evident. This structure greatly decreased the oxygen permeability coefficient compared to the pure LLDPE and the barrier percolation threshold because of the existence of the LLDPE/ EVOH/LLDPE-g-MAH blend layers, and the LLDPE layers diluted the concentration of EVOH in the whole composites. In addition, the effects of the layer thickness ratio of the EVOH/LLDPE/LLDPE-g-MAH and LLDPE layers and the layer number on the barrier properties of the layered composites were investigated. Figure 9. Effect of the layer number on the OPC of the microlayer composites with 50 wt % EVOH in the blend layer. ARTICLE WILEYONLINELIBRARY.COM/APP WWW.MATERIALSVIEWS.COM

Comparative study on the deformation behavior, structural evolution, and properties of biaxially stretched high‐density polyethylene/carbon nanofiller (carbon nanotubes, graphene nanoplatelets, and carbon black) composites

“…The oxygen permeability coefficient ( ) was determined by monitoring the real‐time pressure changes in the lower chamber in 20 h, and the was calculated using Eq. . Two specimens were measured for each type.…”

Recent Updates on the Barrier Properties of Ethylene Vinyl Alcohol Copolymer (EVOH): A Review

“…Alipour et al (2015) found that the P O 2 for a 5-and 19-layer structure of EVOH, LDPE and a PE adhesive was the same, however an improvement in n-hexane uptake and improvement of mechanical strength were noted in the 19-layer structure compared to the 5-layer structure. [61] Su et al (2015) prepared blends of EVOH32 and linear low-density polyethylene with 5% LLDPE grafted with 1% maleic anhydride (EVOH/LLDPE/LLDPE-g-MAH). These blends were coextruded with LLDPE using microlayer extrusion technology.…”

“…The microlayer structure decreased the barrier percolation threshold from 50 wt% EVOH for a conventional EVOH/LLDPE/LLDPE-g-MAH blend to about 5.6 wt% in a 16 layer microstructure. [62] Microlayer technology can also help to maintain the barrier properties of films after flexing because of its improved flex crack resistance. [59]…”

Impact of Nanoconfinement on Polylactide Crystallization and Gas Barrier Properties

“…18−23 However, results were often behind expectation. 10,19,22,23 Amorphous-phase dynamics play also a decisive role in the overall barrier properties. In the case of PLA, this was studied in the last years by several groups [3][4][5]24 and summarized in the recent review of Sonchaeng et al 2 However, the impact of confinement of PLA between the hard walls of a second glassy polymer on the barrier properties in such a context has not been studied yet.…”

“…In particular, it was observed that coextruding PEO, PCL or polypropylene (PP) between hard confining layers led to unique single crystalline lamellas oriented parallel to the layers (in-plane). − Because the impermeable lamellas with large aspect ratios were oriented perpendicularly to the permeant flux, multiple orders of magnitude reduction in gas permeability was achieved compared with the bulk. The orientation of crystals is thus an important parameter, and many reports exist on the subject. − However, results were often behind expectation. ,,, Amorphous-phase dynamics play also a decisive role in the overall barrier properties. In the case of PLA, this was studied in the last years by several groups − , and summarized in the recent review of Sonchaeng et al However, the impact of confinement of PLA between the hard walls of a second glassy polymer on the barrier properties in such a context has not been studied yet.…”