Modification of water vapour transfer rate of low density polyethylene films for food packaging

摘要

One of the most common materials used for packaging is low density polyethylene film. To improve the water vapour transfer of the film, zeolite-polymer composite films and perforated films are produced. The solid-low density polyethylene composite films were prepared by extrusion of polyethylene beads coated with hot zeolite particles of a definite size range in an industrial extruder (-420/+212, -212/+106, -106/+53 μparticles/g of polyethylene beads). A needle (0.2, 0.5 and 1.75 mm in diameter) attached to the tip of a soldering gun was used for the production of the perforated polyethylene films (1, 3, 6, 12, 18 and 24 holes per 38.5 cm~2). The overall evaluation indicates that the water vapour transfer rates can be modified by the composite and the perforated films, which provides packaging material variety for foods of different moisture content. The solid- polyethylene composite films, showed less permeability to water vapour than the polyethylene film. This may be attributed to two reasons: the available polyethylene area is reduced by the presence of solid particles and these solid particles have an important sorption property. The water vapour transfer rates increased by the perforated films.