Photo-oxidation effects on mechanical properties of epoxy matrixes: Young's modulus and hardness analyses by nano-indentation

Delobelle, P.; Guillot, L.; Dubois, C.; Monney, L.

doi:10.1016/s0141-3910(02)00104-0

Cited by 25 publications

(13 citation statements)

References 13 publications

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“…As exposure time increases, a more significant morphological evolution is generally observed on the sample surface; however, significant changes in mechanical performance or appearance may not be detected using conventional testing until the degradation has progressed to an advanced state. 8 In order to monitor the coating property changes with exposure from the early stages of degradation, nondestructive techniques with the ability to characterize surface properties with micro-to nanoscale spatial or depth resolution are required. Information obtained from such characterization can then be used to provide a more complete understanding of degradation mechanisms, providing a fundamental basis for predicting the service life of polymer coatings.…”

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confidence: 99%

“…8,[21][22][23] This technique is characterized relative to traditional indentation techniques by the small radius of the indentation probes, the continuous and simultaneous measurement of forces and displacements, the extremely high force and displacement resolutions, and the large ranges of applied forces and displacements. These capabilities allow for the study of a variety of materials with micrometer and submicrometer scale resolution, both in lateral dimension and in penetration depth.…”

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confidence: 99%

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Advanced techniques for nanocharacterization of polymeric coating surfaces

Nguyen

Sung

et al. 2004

J Coat. Technol. Res.

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Surface properties of a polymeric coating system have a strong influence on its performance and service life. However, the surface of a polymer coating may have different chemical, physical, and mechanical properties from the bulk. In order to monitor the coating property changes with environmental exposures from the early stages of degradation, nondestructive techniques with the ability to characterize surface properties with micro-to nanoscale spatial resolution are required. In this article, atomic force microscopy has been applied to study surface microstructure and morphological changes during degradation in polymer coatings. Additionally, the use of AFM with a controlled tip-sample environment to study nanochemical heterogeneity and the application of nanoindentation to characterize mechanical properties of coatings surfaces are demonstrated. The results obtained from these nanometer characterization techniques will provide a better understanding of the degradation mechanisms and a fundamental basis for predicting the service life of polymer coatings. P olymeric coatings are widely used in buildings, bridges, automobiles, and electronic equipment for both functional and aesthetic purposes. Despite great improvements in coatings technology, problems still exist in the long-term performance of polymeric coatings exposed to environments such as ultraviolet light, humidity, temperature, and other aggressive conditions. Generally, the surface properties of a coating system have a strong influence on its performance and service life. These properties include surface morphology and microstructure, surface chemistry, optical appearance, and surface mechanical properties such as hardness, modulus, and scratch resistance. Application-specific performance requirements often create complicated interactions between these properties that are important to quantify as a function of service conditions. However, the surface of a polymeric coating system may have different chemical, physical, and mechanical properties from the bulk. 1,2 For example, the concentration of low surface-energy materials is often higher at the air surface than in the bulk, 3,4 especially in a multicomponent coating system. Thus, characterization of bulk material properties might not be sufficient for predicting performance. Techniques with sensitivity to the surface chemical, physical, and mechanical properties are required.An additional factor that complicates the prediction of coating performance and service life is that polymer coatings are heterogeneous 5,6 and contain nano-to micrometer scale degradation-susceptible regions. Degradation of a polymer coating is believed to start from these degradation-susceptible regions on the surface and then grow laterally and vertically. In the early stages of degradation, even though obvious chemical changes have been observed, the physical changes of the coating surface could still be small, 7 so that degraded regions such as pits may have dimensions that are on the order of nanometers in depth and perhap...

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Advanced techniques for nanocharacterization of polymeric coating surfaces

Nguyen

Sung

et al. 2004

J Coat. Technol. Res.

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“…It has been demonstrated by various methods (e.g., IR-ATR spectroscopy, 38 X-ray analysis with EDS, 37 and nano-indentation 63 ) that the oxidation zone thickness in densely crosslinked epoxy coatings, with high glass transition temperatures, exposed to constant UV radiation is 1.8-2 lm and that the rest of the coating is identical to the unexposed coating (both chemically and mechanically). It therefore seems plausible to assume that either a lack of oxygen or of UV radiation in the bulk of the coating has a strong influence on the oxidation zone thickness in these systems.…”

Section: Analysis Of Rate Phenomena Potentially Influencing the Oxidamentioning

confidence: 99%

“…Under these conditions, the presence of photoproducts deeper in the coating may be expected, but such an observation has not been reported by Monney and co-workers in their many analyses of the oxidation zone thickness. 37,38,63,[65][66][67] The reason for this could be that the concentration of photoproducts does not reach a sufficiently high value for detection in the time available.…”

Section: Natural Exposure Vs Artificial Exposurementioning

confidence: 99%

Model-based analysis of photoinitiated coating degradation under artificial exposure conditions

Kiil

2012

J Coat Technol Res

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Coating degradation mechanisms of thermoset coatings exposed to ultraviolet radiation and humidity at constant temperature are investigated. The essential processes, photoinitiated oxidation reactions, intrafilm oxygen permeability, water absorption and diffusion, reduction of crosslink density, and development of a thin surface oxidation zone are quantified and a mathematical model for degrading coatings developed. Front-tracking techniques are used to determine the rate of movement of the oxidation and ablation fronts, the positions of which define the extension of the surface oxidation zone. Three previous and independent experimental investigations with two-component, densely crosslinked, epoxy-amine model coatings were selected for verification of the mathematical model. Simulations can match and explain transient mass loss and coating thickness reduction data and are in agreement with infrared measurements of carbonyl groups formed in the surface zone. The thickness of the stable surface oxidation zone, which is established after an initial ablation lag time, is estimated by the model to 0.5-2 lm in good agreement with previous measurements. Simulated concentration profiles of active groups, oxygen, and radicals in the stable surface oxidation zone are presented and analyzed. The mathematical model can be used for obtaining a quantitative insight into the degradation of thermoset coatings and has potential, after further development, to complete commercial coatings and dynamic exposure conditions, to become a supplementing tool for predicting in-service coating behavior based on accelerated laboratory measurements.

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“…Moreover, atomic force microscopy (AFM) nanoindentation tests [8] have shown that an oxidised layer was formed at the surface of the sample. The thickness of this layer has approximately been evaluated as 1.8-2.0 mm.…”

Section: Introductionmentioning

confidence: 99%

Study of the Degradation of an Epoxy/Amine Resin, 2

Mailhot

Morlat‐Thérias

Bussière

et al. 2005

Macro Chemistry & Physics

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Summary: The degradation behaviour of a flexible epoxy/amine resin has been studied. The resin, made of DGEBA and polyether diamine (Jeffamine® D2000) has been submitted to photooxidation, photolysis (in absence of oxygen) and thermooxidation experiments. The nature and the mechanism of formation of the products have been previously reported in the first paper of this series. In this paper, the rate of formation of the degradation products and their distribution within the sample are discussed. The change in the rate of degradation observed after 30 h of irradiation in artificial ageing at λ > 300 nm in the presence of oxygen, measured by ATR‐FTIR and UV‐Vis spectrometries, is explained by a large attenuation of light intensity by the chromophoric photoproducts formed. The photooxidation profiles measured by micro‐FTIR showed a heterogeneous distribution of the photoproducts in the first 250 μm of the exposed surface. The formation of these photoproducts is associated to chain scission reactions. This was clearly evidenced by the decrease of stiffness measured by AFM nanoindentations in the same first 250 μm.Stiffness profiles measured by AFM nanoindentation of a photooxidised epoxy/amine sample.magnified imageStiffness profiles measured by AFM nanoindentation of a photooxidised epoxy/amine sample.

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Photo-oxidation effects on mechanical properties of epoxy matrixes: Young's modulus and hardness analyses by nano-indentation

Cited by 25 publications

References 13 publications

Advanced techniques for nanocharacterization of polymeric coating surfaces

Advanced techniques for nanocharacterization of polymeric coating surfaces

Model-based analysis of photoinitiated coating degradation under artificial exposure conditions

Study of the Degradation of an Epoxy/Amine Resin, 2

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