Observation of the Effect of Aging on the Structural Changes of Polyurethane/Polyurea Coatings

Abstract

In this study, polyurethane/polyurea coatings were exposed to four different types of aging: aging in the natural environment (NC), accelerated ultraviolet aging (UV), aging in a sodium chloride solution (NaCl), and thermal aging (TC). To monitor the changes that occurred during these processes, the thickness was measured and microscopic and macroscopic observations were conducted continuously. The samples aged under various conditions were then subjected to spectroscopic (FTIR) and thermal (TGA) analysis to determine the possible structural changes in the coatings. The dependence of aging conditions on the physicochemical properties of the tested coating surfaces was thoroughly investigated and characterized by the water contact angle and surface free energy. Adhesion tests were performed after the established aging period. The results show that different aging conditions have a tremendous effect on the appearance and pull-off strength. The coatings that age in a NaCl solution are more affected in terms of their adhesion.

Degradation Behavior and Lifetime Prediction of Polyurea Anti-Seepage Coating for Concrete Lining in Water Conveyance Tunnels

“…As aging temperature and duration increase, the destruction mode transitions to class B and class C failures, characterized by the retention of epoxy and polyurethane undercoating on the exposed concrete surface. These findings corroborate those reported by other researchers [19,31,34]. At 80 • C water temperature, the adhesive interface degrades more rapidly due to water pressure (Figure 10).…”

Synthesis and Characteristic Valuation of a Thermoplastic Polyurethane Electrode Binder for In-Mold Coating

“…This was measured to identify the main peak of the PU. The C=O in the carbonate and urethane bonds identified asymmetric and symmetric stretching vibration peaks at 1738 cm −1 and 1676 cm −1 , respectively [44], while the secondary amine in the urethane bond identified an N-H stretching vibration peak at 3356 cm −1 and a C-N stretching vibration peak and an N-H bending vibration peak at 1528 cm −1 . It can be seen that the transmittance of the N-H bending vibration peak increases as the content of PCD decreases in the PHEI-PU series, which is due to the fact that the molecular weight of ISBD is smaller compared to the PCD, thus forming more urethane bonds; PHEI-PU 5 with a larger content of ISBD has the largest value [29].…”

The degradation of poly(1-butene) extrudates subjected to artificial and natural aging

“…2). Based on this comparison, the yellow index (in the case of undyed polymers) indicated the degree of degradation [43]. The yellow index was higher in naturally weathered samples due to the presence of external influences not present during artificial aging, e.g., a higher amount of oxygen, rain, and changeable surrounding temperature, which resulted in different chemical degradation processes and formation of different chemical compounds; these conditions cannot be precisely defined due to the impossibility of deconvoluting the peaks in the range of carbonyls (Fig.…”