New strategy to assess the performance of organic coatings during ultraviolet–condensation weathering tests

Bedoya, Franky Esteban; Gallego, Liliana; Bermúdez, Ana; Castaño, Juan G.; Echeverría, Félix; Calderón, Jorge A.; Maya, J.G.

doi:10.1016/j.electacta.2013.09.064

Cited by 14 publications

(12 citation statements)

References 19 publications

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“…Using maximum and minimum values from the time-course EIS spectra of key elements in the EEC in Figure 5d, mechanical stress within a film can be estimated by an electrochemical stress (ES) index 43 shown in eq 3:In this calculation, a resulting value close to zero indicates low stress, whereas a value of 3 is the theoretical maximum. By this metric, the PVDF resin (control film without the nanoclay) had an ES = 2.66 after 4500 h of weathering, which was the highest stress index in the study and makes this coating the least weatherable.…”

Section: Resultsmentioning

confidence: 99%

Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings

2016

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Nanoclays are small enough to appear optically transparent, yet they have large surface-to-volume and high aspect ratios that can significantly inhibit water diffusion when incorporated into protective coatings. Clear coatings, which minimally affect the aesthetics of metalworks, are commonly applied to outdoor metalworks, such as sculptures, to prevent and slow corrosion. In recent years, waterborne clear coatings, rather than solvent-based clear coatings, are increasingly used in many applications to reduce the quantity of volatile organic components in the formulation, yet the performance of dry films produced from waterborne colloidal suspensions is generally poorer. In this work, we aim to improve the barrier properties of a highly weatherable waterborne acrylic/polyvinylidene fluoride emulsion by adding a synthetic nanoclay, Laponite, into the formulation. To improve clay–polymer compatibility, the clay was covalently modified using an acetoxy or perfluoroalkyl silane monomer that is reactive with the hydroxyl groups at the edges of the Laponite platelets. Cation exchange on the clay faces using phosphorylcholine was conducted to increase the stability in water and characterized by zeta potential. Resulting changes in barrier properties of the polymer nanocomposite films were characterized by gravimetry, colorimetry, and electrochemical impedance spectroscopy. Surface ablation after accelerated artificial weathering was monitored by attenuated total internal reflectance Fourier transform infrared microspectroscopy and Raman microspectroscopy, thin film X-ray diffraction (TF-XRD) and gloss and thickness measurements. The composite films showed many improved properties: reduced water sensitivity and ultraviolet-induced polymer degradation, which increased the barrier properties and reduced the diffusion constants over both short- and long-term weathering studies compared with films without nanoclays. The diffusion constant measured for the highest performing composite film showed that the performance gap between relevant water- and solvent-borne coatings used to protect outdoor metals was narrowed by half.

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Section: Resultsmentioning

confidence: 99%

Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings

2016

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“…The absorption in the region of 2390 -2270 cm -1 is a noticeable phenomenon in Fig. 2 c, which may be attributed to the formation of -NCO during UV/O3 ageing process [10]. The increase of the absorption in the region of 1763 -1640 cm -1 indicates that new carbonyl species including quinine-imide structure may generate [11].…”

Section: Uv-vis Spectramentioning

confidence: 88%

“…Our research group studied effects of additives on weather-resistance properties of polyurethane films exposed to ultraviolet radiation and ozone atmosphere [10]. Until now, we have not found other literature compared the accelerated ageing behaviour of the polyurethane film exposed to UV radiation, O3 atmosphere and UV/O3 environment.…”

Section: Introduction *mentioning

confidence: 99%

Influence of Environment on Ageing Behaviour of the Polyurethane Film

Wang¹,

Sun²,

Jian-feng³

et al. 2016

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In this work, UV-Vis spectra, FT-IR spectra, colour difference, yellowness index, and SEM micrographs were used to study the accelerated ageing behaviour of polyurethane films that exposed to UV radiation, O3 atmosphere, and UV/O3 integrated environment. During 200 hours of exposure in three different environment, the UV absorbance, the colour difference, the yellowness, and the absorption of-NH/-OH and-C=O bands in FT-IR spectra of the films increase gradually with increasing exposure time, respectively, and the films exposed to the three environments have different colour difference, yellowness index, UV-Vis spectra, and FT-IR spectra. The films are vulnerable to degradation and yellowing in the following environment order: O3 < UV < UV/O3. After exposure to UV radiation or O3 atmosphere, some degradation products and blisters are formed on the film surface. After exposure to UV/O3 integrated environment, there are strip blisters and micro-cracks on the film surface, and exists an obvious synergism between UV radiation and O3 atmosphere in accelerating the ageing of the polyurethane films.

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“…An appropriate accelerated degradation test, which reproduces blisters within a reasonable timescale, is necessary to estimate the lifetime via laboratory experiments. Several studies have considered different accelerated degradation methods for coated steel plates [9][10][11][12][13][14][15][16][17]. For example, thermal cycling tests accelerate the degradation of coating systems by rearranging the polymer molecule chain because heat loosens the polymer network and accelerating water accumulation in the coating, which increases the transport rate of the electrolyte solution [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Accelerated Degradation Methods to Cause Blisters for Non-Defective Vinyl Ester Resin Glass Flake Organic Coatings

2022

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Organic coatings are applied as a corrosion prevention measure, but their effectiveness may degrade over time. In this study, the acceleration effects of typical degradation methods in non-defective vinyl ester resin organic coatings containing glass flakes such as high-temperature immersion and immersion in chemical accelerators are clarified using physiochemical techniques. Immersion in an acetic acid (AcOH) aqueous solution causes resin swelling, and the behaviors are quantitatively evaluated through gravimetric, thickness, and electrochemical impedance spectroscopy (EIS) measurements. Furthermore, a combined process of immersion in hydrofluoric acid and an AcOH aqueous solution reduces the electrical properties and eventually blisters the thick coating surface. This result suggests that an appropriate combination of the resin swelling and the glass degradation (glass dissolution and/or formation of the gap between glass and resin) decrease mechanical properties of the glass flake coating and causes blisters. In order to help the health diagnosis of the visually non-defective aged glass flake coating, the relationship between the electrical characteristic values and the invisible degradation by accelerated tests is finally indicated.

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New strategy to assess the performance of organic coatings during ultraviolet–condensation weathering tests

Cited by 14 publications

References 19 publications

Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings

Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings

Influence of Environment on Ageing Behaviour of the Polyurethane Film

Investigation of Accelerated Degradation Methods to Cause Blisters for Non-Defective Vinyl Ester Resin Glass Flake Organic Coatings

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