Processing/Structure Relationships of Mica-Filled PE-Films with Low Oxygen Permeability

Abstract

Lamellar microstructures can decrease gas and vapor permeability by increasing the diffusive path or the socalled "tortuosity" in plastic films. In this research, phlogopite mica flakes were used as oxygen barrier materials in films produced in a blown film extrusion line. Both high and low density polyethylenes as well as their blends were used as matrices with mica concentrations not exceeding 10-wt.-%. A decrease in oxygen permeability of both low density and high density polyethylene films was achieved with increasing volume fraction of mica. Film morphologies indicated strong flow-induced orientation of the flakes in overlapping, discontinuous layers that were reasonably well oriented parallel to the surface of the films. Melt shear viscosity and melt strength of the mica compounds and tensile properties of films were also examined and correlated with processability. Overall, it was found that, by contrast to the LDPE compounds, optimization of the barrier properties of the HDPE films was a compromise between the desired reduction in permeability and the loss in processability and film ductility. The experimentally determined elastic modulus values were found to be in relatively good agreement with predictions from flake reinforcement theories. A predictive model for the analysis of the permeability results, assuming that both mica flakes and the crystalline domains of the films were impermeable to oxygen, was able to describe the permeability results in spite of several simplifying assumptions.International Polymer Processing downloaded from www.hanser-elibrary.com by Kungliga Tekniska on August 18, 2015For personal use only.

Characterization of the barrier properties of composites of HDPE and purified cellulose fibers

“…In composites, fillers are mainly used to enhance the mechanical properties of engineering plastics (Gay et al 2003). However, since more recently composites have also being considered to tailor the barrier properties of packaging materials (Xanthos et al 1998;Lagaron et al 2005).…”

Mechanical, Thermal, and Flow Properties of HDPE–Mica Composites

“…Recently, the effects of some fillers, such as silicone dioxide, kaolin, diatomite, and mica, on the properties of filled HDPE composites have been investigated [2][3][4][5][6]. Mun˜oz et al [3] studied the crystallinity of HDPE blends filled with silicone dioxide additive, and the results of the differential scanning calorimeter (DSC) test showed differences in crystalline behavior between binary and ternary composites.…”

“…In binary composites, the crystallization degree increased up to 10 wt% of the silicone master batch (SMB) content; beyond which the crystallization degree decreased, while in ternary composites, a reverse behavior was observed. HDPE filled with mica could decrease permeability of the material, and it could be made into a variety of containers like tankers, and so on [4]. Xanthos et al [4] studied the oxygen permeability of mica-filled HDPE-films, and a decrease in oxygen permeability of the HDPE films was achieved with increasing volume fraction of mica.…”

“…HDPE filled with mica could decrease permeability of the material, and it could be made into a variety of containers like tankers, and so on [4]. Xanthos et al [4] studied the oxygen permeability of mica-filled HDPE-films, and a decrease in oxygen permeability of the HDPE films was achieved with increasing volume fraction of mica.…”

Smart polymeric coatings—recent advances

“…Polymeric coatings containing aligned impermeable platelets of high-aspect ratio, or additives reactive toward corrosive liquids, can significantly reduce permeability of liquids and vapors versus the unmodified polymers. 57,58 This permeability reduction has been shown to impart barrier properties and inhibit corrosion of aluminum substrates coated with epoxy filled with mica flakes as a result of increased tortuosity. 59 The use of cationic (e.g., montmorillonite) or anionic (e.g., hydrotalcite) nanoclays after exfoliation and planar orientation of the individual lamellae would also be expected to provide barrier properties.…”