Water transport in epoxy/polyurethane interpenetrating networks

Abstract

Diffusion of water in epoxy-polyurethane (PU) interpenetrating networks was investigated using gravimetry, time-resolved ATR-FTIR, and 2D correlation analysis. In this study, the amount of PU component and the length of polyethylene oxide soft block in them were systematically varied to determine their influence on water uptake. The diffusion coefficients were calculated and anomalous water diffusion is well described by the Carter and Kibler model. Water molecules of four different states

Water in Epoxy Coatings: Basic Principles of Interaction with Polymer Matrix and the Influence on Coating Life Cycle

“…The Langmuir-type model showed the greatest efficiency among those described for non-Fickian diffusion in epoxy coatings [9,26,34,37,39,51,[54][55][56][57][58][59]. For example, Glaskova et al [51] quantified the performance of a number of the above models for a selected commercial epoxy resin and found that Langmuir-type and relaxation models provide results that have adequate agreement with the experimental data.…”

“…These ranges contain information about both intermolecular and intramolecular hydrogen bonding. The region from 3700 to 3100 cm −1 is more intense and contains more information about the hydrogen bonds, while that of 1700-1600 cm −1 is less informative due to the overlapping with other functional groups and low signal intensity [9,60,66].…”

“…According to the research [9,15,60,66,73,74], the intensity of the bands corresponding to OH-group vibrations increases, and the peak broadens with the increasing diffusion time.…”

“…The selected region has a single overlapping broad peak that cannot be used in diffusion studies without some additional processing. Therefore, according to the results of deconvolution, it is customary to distinguish the following ranges: 3800-3500 cm −1 (S 0 , free/mobile water molecules), 3600-3400 cm −1 (S 1 , water molecules bound by weak hydrogen bonds), 3500-3200 cm −1 (S 2L , moderately bound water molecules), and 3300-3100 cm −1 (S 2T , strongly bound water molecules) [9,15,60,62,63,66,71,75]. Figure 2 illustrates the possible deconvolution peaks.…”

“…This method better distinguishes the overlapping peaks and determines the correlation between them. Two-dimensional correlation FTIR spectroscopy has a number of advantages: it can detect overlapping spectroscopic information, it can easily search for minor changes in peaks, and it can identify specific sequence of events occurring in the system under the influence of external factors [9,15,60,62,65].…”