(649c) Evaluation of Surface Moisture Sorption and Diffusion in Materials

Vapor sorption and outgassing in materials can lead to unwanted changes in physical and chemical properties.^1-3 Diffusion and outgassing from a material can impact the material itself and others in close contact in a system which in turn influences the entire system functionality.

The sorption diffusion process is dynamic and consists of different sorption modes and varies dramatically in different materials. Therefore, a detailed understating of the moisture uptake and diffusion is crucial. In this study, we investigate the moisture sorption and diffusion phenomena of high-density polyethylene (HDPE) materials using a combined experimental and modeling approach. Gravimetric type vacuum dynamic vapor sorption (DVS) experiments were employed to measure the moisture uptake and used for the modeling. Analysis of moisture uptake data suggested that the uptake of moisture by HDPE is likely on the surface only as the material is very dense and hydrophobic compared to other polymeric materials such as PDMS and polyurethanes. Modeling results show that the major moisture sorption contribution is due to Langmuir-type surface mechanism (<40 % RH) and the multilayer sorption mechanism dominates at higher RH condition.

Figure 1 shows the experimental data obtained for HDPE material at 25°C using the DVS technique and model simulations using our surface-sorption model. In this talk, we will present results and application of the model to other materials such as metals.

Fig.1: Moisture sorption by HDPE and surface-sorption model simulations at 25°C.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

LLNL-ABS-820951-DRAFT

References:

¹ H. N. Sharma et al., Sci Rep 7 (2017) 2942.

² S. J. Harley et al., Chemphyschem 15 (2014) 1809.

³ H. N. Sharma et al., J. Chem. Phys. 145 (2016) 114905.