Formaldehyde release from acrylic/melamine coatings during photolysis and the mechanism of photoenhanced cross-link hydrolysis

Gerlock, John L.; Dean, Mary J.; Korniski, Thomas J.; Bauer, David R.

doi:10.1021/i300023a014

Cited by 37 publications

(14 citation statements)

References 4 publications

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“…10). Quite some early work has been performed and published on the thermal degradation [36][37][38][39] and hydrolysis [32] of melamin-formaldehyde resins, but rather little is published on the stability of this resin type when outdoor weathering conditions are applied [3,31]. The melamine units in a melamine-formaldehyde resin (MF resin) are connected via methylene-ether bridges (see structure (1) in Fig.…”

Section: Sem/edx Of the Surfacesmentioning

confidence: 99%

“…10) and methylene bridges (structure (5) in Fig. 9) [3,31,32]. Under the influence of UV radiation in an oxygencontaining atmosphere (air), the formation of a carbonyl group at the methylene carbon is proposed, resulting in amide-like (structure (6) in Fig.…”

Section: Sem/edx Of the Surfacesmentioning

confidence: 99%

“…10) [32]. At elevated temperatures, elimination of CO 2 or formaldehyde [31,32] seems possible, resulting in free -NH 2 groups (structure (4) in Fig. 10).…”

Section: Sem/edx Of the Surfacesmentioning

confidence: 99%

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Visualisation and characterisation of ageing induced changes of polymeric surfaces by spectroscopic imaging methods

Eder¹,

Spoljaric-Lukacic²,

Chernev

2012

Anal Bioanal Chem

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A polymeric resin material was chosen as the model system to visualise the ageing-induced chemical surface changes with molecular spectroscopic imaging techniques and correlate these results to physical properties such as colour changes. The influence of light radiation, temperature and humidity on the polymeric surfaces was analysed by means of attenuated total reflection infrared imaging, Raman imaging spectroscopy and scanning electron microscopy. Samples were analysed before, during and after the weathering/ageing tests. From these combined data, the mechanisms for the damaging of the resin surface under the various environmental conditions (as applied in the accelerated ageing tests) were deduced. Photo-oxidative decay of the resin leading to a degradation of the uppermost surface layers as well as hydrolysis of the aged surface was identified. The combination of the spectral and spatial data as obtained from spectroscopic imaging with the morphological and elemental information of scanning electron microscopic mapping experiments turned out to be highly advantageous for the elucidation of ageing processes. A correlation between the molecular spectroscopic data and the results from the macroscopic colour difference measurements was found.

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Section: Sem/edx Of the Surfacesmentioning

confidence: 99%

Section: Sem/edx Of the Surfacesmentioning

confidence: 99%

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Visualisation and characterisation of ageing induced changes of polymeric surfaces by spectroscopic imaging methods

Eder¹,

Spoljaric-Lukacic²,

Chernev

2012

Anal Bioanal Chem

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show abstract

“…These include mainly hot-cold shocks, humidity, and UV radiation. [1][2][3] In addition, a rarely reported type of degradation can also be observed in coatings exposed to various pollutants originating from different natural sources. [4][5][6][7][8] When coatings are exposed to a natural environment, chemical and/or physical influences can occur which may lead to degradation.…”

Section: Introductionmentioning

confidence: 99%

Studying the effects of the chemical structure of an automotive clearcoat on its biological degradation caused by tree gums

2011

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The effects of artificial and natural tree gums on the mechanical, chemical, and aesthetic performances of two automotive acrylic/melamine clearcoats were studied. To this end, two clearcoats with different acrylic/melamine ratios were investigated. Biological experiments were performed under post-aging conditions using an accelerated weathering test. Analytical techniques including optical microscopy, scanning electron microscopy (SEM), gloss measurement, FTIR, and DMTA analyses were utilized to reveal the responses of the coating system upon exposure to the aforementioned biological materials. Contact angle measurements were also conducted to estimate the surface energy of the coatings. Greater crosslinking density, together with a higher T g and damping behavior of the clearcoat, indicative of a greater degree of cure, were obtained as the ratio of melamine crosslinker increased. It was shown that both Arabic and natural tree gums could strongly attach to the clearcoats' surface, imposing a significant stress during the drying process, thereby leading to a physical failure. In addition, the acidic nature of these biological materials leads to a chemical alteration in the clearcoats' structure. The greater crosslinking density and lower hydrophilicity of the clearcoats containing higher melamine crosslinker were responsible for the weaker interaction of gums with the surface. This showed a greater capability for stress damping. Small surface cracks with fracture morphology on the coatings exposed to biological materials at higher exposure times (in the xenon test) were also observed. This is discussed based on the adhesion of the coatings to gums at longer exposure times, because of significant stress.

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“…As such, these natural conditions can be responsible for accelerating the failure of the clearcoats chemically or physically. [1][2][3][4][5][6][7] Biological degradation is one of the rarely reported kinds of degradations which can be produced by different biological compounds. This kind of degradation, which irretrievably affects the coating property, can be influenced by various outdoor conditions.…”

Section: Introductionmentioning

confidence: 99%

The role of basecoat pigmentation on the biological resistance of an automotive clearcoat

2010

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This work aims to study the effect of various natural and artificial biological compounds on an automotive acrylic/melamine clearcoat applied over silver and black basecoats containing pigments. The visual performance of the coating system was evaluated at different aging conditions. To this end, analytical techniques including optical microscopy, scanning electron microscopy, gonio-spectrophotometery, gloss measurement, ATR-FTIR spectroscopy, and DMTA analysis were utilized to investigate the optical and mechanical response of the system upon exposure to the biological materials. Results indicated different effects produced by gums and bird droppings on both silver and black systems at all aging processes. In addition, a more severe effect of biological attacks was observed on the clearcoat samples applied on the black basecoat which had experienced postaging conditions. However, it was found that pancreatin and bird droppings influence the coating systems more severely compared to the natural and synthetic Arabic gums.

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Formaldehyde release from acrylic/melamine coatings during photolysis and the mechanism of photoenhanced cross-link hydrolysis

Cited by 37 publications

References 4 publications

Visualisation and characterisation of ageing induced changes of polymeric surfaces by spectroscopic imaging methods

Visualisation and characterisation of ageing induced changes of polymeric surfaces by spectroscopic imaging methods

Studying the effects of the chemical structure of an automotive clearcoat on its biological degradation caused by tree gums

The role of basecoat pigmentation on the biological resistance of an automotive clearcoat

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