Desiccant films made of low-density polyethylene with dispersed calcium oxide: Water vapor absorption, permeation and mechanical properties

Polymers with dispersed desiccants are relevant for various packaging applications to protect packaged goods from water vapor. The intention of this study was to analyze and to describe a relevant system. Therefore, films with calcium oxide (CaO) were investigated, because such materials are hardly described in scientific literature. Monolayer films with 0.14 to 0.51 g dispersed CaO per 1 g film (PE‐LD) were prepared and they absorbed up to 0.2 g water vapor per 1 g of film. The water vapor absorption was described by effective diffusion coefficients. By the use of effective diffusion coefficients and the absorption capacity, the absorption behavior of layers with various thicknesses can be estimated. The steady state (effective) water vapor permeation coefficients of the films with dispersed CaO were a factor of 2 to 24 (8.4 to 101.5 mg cm [cm2 s Pa]-1 × 1012, at 23 °C) higher than for pure PE‐LD films (4.26 mg cm [cm2 s Pa]−1 × 1012, 23 °C). The tensile stress changed only slightly (pure PE‐LD: 9.5 N mm−2; PE‐LD with 0.14 g dispersed CaO per 1 g film: 8.1 N mm−2; PE‐LD with 0.51 g dispersed CaO per 1 g film: 10.5 N mm−2), while the tensile strain at break was reduced with higher CaO concentration from 318% (pure PE‐LD) to 10% (PE‐LD with 0.51 g dispersed CaO per 1 g film).