scholarly journals Chemical Degradation and Color Changes of Paint Protective Coatings Used in Solar Glass Mirrors

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 476
Author(s):  
Mohamed Guerguer ◽  
Sanae Naamane ◽  
Zineb Edfouf ◽  
Olivier Raccurt ◽  
Hassan Bouaouine
Keyword(s):  
Protective Coatings ◽  
Natural Aging ◽  
Attenuated Total Reflection ◽  
Chemical Degradation ◽  
Complete Analysis ◽  
Color Changes ◽  
Colorimetric Measurements ◽  
Marine Site ◽  
Service Conditions ◽  
Paint Coatings

This paper reports a study of the influence of outdoor natural aging on paint coatings applied to the back of three commercial solar glass mirrors (A1, C2, and D2) under two different exposure environments (marine and desert) in Morocco for a period of about three years. The aging assessment was carried out through colorimetric measurements and FTIR-ATR (Attenuated total reflection-Fourier transform infrared) analyses of the top coat paints. The obtained results demonstrate that the tested coating system had a high resistance at the desert site. Under the desert environment, no obvious changes to the coating occurred after 350 days. However, at the marine site, some color changes were detected, and the coating got yellow and more matte, especially for mirror A1. FTIR-ATR analyses have indicated many modifications in the intensity of many bonds of infrared spectra especially for paint of this mirror type (A1). This chemical degradation is not only due to UV degradation but also related to many factors, such as humidity, salinity, and rainfall. This finding was concluded after the faster degradation observed on samples exposed at the marine site. The present study confirms the need to use different exposure environments for testing the limits of new protective systems for solar glass mirrors rather than using only the real service conditions. Finally, accelerated tests are necessary for understanding the effect of each degrading parameter and their results should be compared to outdoor tests data for a complete analysis of coatings durability.

scholarly journals Influence of Mechanical and Chemical Degradation in the Surface Roughness, Gloss, and Color of Microhybrid Composites

2017 ◽  
Vol 18 (4) ◽  
pp. 283-288 ◽  
Author(s):  
Cleidiel AA Lemos ◽  
Silvio J Mauro ◽  
Paulo H dos Santos ◽  
André LF Briso ◽  
Ticiane C Fagundes
Keyword(s):  
Surface Roughness ◽  
Clinical Significance ◽  
Composite Resin ◽  
Color Change ◽  
Wilcoxon Test ◽  
Chemical Degradation ◽  
Color Changes ◽  
Final Data ◽  
Properties Of Materials ◽  
Spearman Test

ABSTRACT Aim The aim of this study was to investigate the association of different degradations on the roughness, gloss, and color changes of microhybrid composites. Materials and methods Ten specimens were prepared for Charisma, Amelogen Plus, Point 4, and Opallis resins. Surfaces were polished and baseline measurements of roughness, gloss, and color were recorded. Specimens were then submitted to chemical and mechanical challenges, and the specimens were reevaluated. Roughness and gloss were analyzed by Kruskal – Wallis and Dunn's test (p < 0.05). Color change (ΔE) was analyzed by one-way analysis of variance and Tukey's tests (p < 0.05). The initial and final data were compared using the Wilcoxon test (p < 0.05). Spearman test checked the correlation between the roughness and gloss (p < 0.05). Results Regarding surface roughness and gloss, there was no difference between composites before challenges. However, all composites showed a significant increase of roughness after challenges, with highest values for Charisma. The gloss was influenced by challenges, evidencing the best gloss for Point 4. Charisma showed the highest value of color change. There was no correlation between surface roughness and gloss for the initial analysis, and after the challenges. Conclusion Composites were influenced by association of challenges, and Charisma showed the highest changes for roughness, gloss, and color. Clinical significance The type of composite resin influenced the properties of materials, which are surface roughness, gloss, and color change. The dentist should be aware of the performance of different brands, to choose the correct required composite resin for each type of patient or region to be restored. How to cite this article Lemos CAA, Mauro SJ, dos Santos PH, Briso ALF, Fagundes TC. Influence of Mechanical and Chemical Degradation in the Surface Roughness, Gloss, and Color of Microhybrid Composites. J Contemp Dent Pract 2017;18(4):283-288.

scholarly journals Effect of In-Office Bleaching on Color and Surface Roughness of Composite Restoratives

2010 ◽  
Vol 04 (02) ◽  
pp. 118-127 ◽  
Author(s):  
Randa Hafez ◽  
Doa Ahmed ◽  
Mai Yousry ◽  
Wafa El-Badrawy ◽  
Omar El-Mowafy
Keyword(s):  
Surface Roughness ◽  
Surface Texture ◽  
Color Change ◽  
Distilled Water ◽  
Bleaching Agent ◽  
Color Changes ◽  
Before And After ◽  
Colorimetric Measurements ◽  
Natural Teeth ◽  
Environmental Sem

Objectives: The purpose of this study was to determine color changes and surface roughness of composites when they were subjected to in-office bleaching.Methods: 12 discs 15 mm in diameter and 2 mm thick were prepared from two shades (A2 & A4) of two composites, Durafil VS (DF) and TPH3 (TPH). Specimens were polished and stored in distilled water for 24 hours at 37°C before being subjected to bleaching, staining, and re-bleaching. Each of the groups of specimens (DF-A2, DF-A4, TPH-A2 and TPH-A4) were subdivided into three subgroups (n=4) and bleached with Beyond, LumaWhite-Plus, and Opalescence-Boost. Specimens were then stained by immersing them in a coffee solution for 48 hours at 37°C, and then they were re-bleached. Colorimetric measurements were performed at baseline, after bleaching, after staining, and after rebleaching. Surface roughness was determined with environmental SEM before and after bleaching. Data were statistically-analyzed.Results: None of the bleaching systems notably changed the color of composites (delta-E<2). Coffee staining affected DF specimens more than TPH. Stained specimens showed variable responses to whitening with no significant color change observed with TPH (delta-E<2) and significant changes observed with DF. Surface roughness significantly changed with bleaching, but the degree varied according to composite shade and bleaching agent.Conclusions: Three in-office bleaching agents had no significant color changes on two composites. DF showed more color change than TPH when immersed in coffee. Stained composites showed different degrees of whitening, with DF showing more response. Bleaching may adversely affect the surface texture of composites. Dentists should take into consideration that composite restorations may not respond to bleaching in the same way that natural teeth do. (Eur J Dent 2010;4:118-127)

scholarly journals Surface preparation as one of the main factors for ensuring the durability of anti-corrosion coatings

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Aleksei Bezgodov ◽  
Ilya Ovchinnikov
Keyword(s):  
Surface Treatment ◽  
Protective Coatings ◽  
Surface Preparation ◽  
Negative Consequences ◽  
Treatment Methods ◽  
Factors Affecting ◽  
Metal Structures ◽  
Optimal Processing ◽  
Main Factors ◽  
Paint Coatings

This article is devoted to the protection of bridge metal structures from corrosion. The article was written with the aim of studying one of the stages of anti-corrosion treatment, namely the preparation of the surface before applying a protective coating. In the article, the authors address the problem of the durability of paint coatings, and point to the main reasons, to a greater extent, affecting the service life. Studying the problem of the durability of protective coatings, the authors distinguish such a stage as preparing the metal surface of the bridge structure before applying the paintwork. The authors tell how important the preparation of the surface is and what negative consequences are possible if it is disturbed or not. For a more detailed study of the problem, the authors consider several methods of preparing the surface of the structure, such as: abrasive blast cleaning, phosphating the surface and heat treatment. When studying the above mentioned methods, the authors describe the technology of the work, the main factors affecting the final result of processing, as well as the positive and negative sides of each of the methods. For each of the surface treatment methods, the authors present illustrations that clearly show the basic concept of the selected treatment option. Summing up the comparative analysis of surface treatment methods before applying anti-corrosion coatings, the authors chose the most optimal processing method, as well as concluded that the importance of this stage and the possibility of its further improvement.

scholarly journals Aging of wood: Analysis of color changes during natural aging and heat treatment

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Miyuki Matsuo ◽  
Misao Yokoyama ◽  
Kenji Umemura ◽  
Junji Sugiyama ◽  
Shuichi Kawai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Oxidation Process ◽  
Color Change ◽  
Natural Aging ◽  
Superposition Method ◽  
Wood Color ◽  
Color Changes ◽  
Heat Treated ◽  
Temperature Superposition ◽  
Wood Analysis

Abstract The color properties of aging wood samples from historical buildings have been compared with those of recent wood samples that were heat treated at temperatures ranging from 90°C to 180°C. The results of kinetic analysis obtained by the time-temperature superposition method showed that the color change during natural aging was mainly due to a slow and mild oxidation process. In other words, heat treatment could accelerate the changes in wood color that occur during aging. In one sample, the color change (ΔE* ab ) after 921 years at ambient temperature was almost equivalent to that of heating (artificial aging) approximately for 6.7 h at 180°C. The results have been interpreted that the aging and the subsequent change in wood color begin at the time of tree harvesting.

Simulated Service Evaluation of Marine Coatings

1967 ◽  
Vol 4 (02) ◽  
pp. 189-195
Author(s):  
R. P. Devoluy ◽  
L. J. Nowacki ◽  
F. W. Fink
Keyword(s):  
Protective Coatings ◽  
Surface Preparation ◽  
Service Evaluation ◽  
Control Surface ◽  
Good Test ◽  
Electrical Currents ◽  
Marine Coatings ◽  
Service Conditions ◽  
Evaluation Techniques ◽  
Reliable Methods

There is a strong demand for faster, and yet reliable, methods of evaluating new protective coatings for underwater marine service. Many of the new materials are so durable that it is impractical to await the outcome of the traditional methods of testing panels in tropical waters. Furthermore, stationary panel exposures in sheltered waters often omit the service conditions that are the controlling causes of failure. For underwater coatings these variables may include exposure to electrical currents (cathodic protection),abrasion, impact, impingement, cavitation, and other velocity effects. Coatings tests applied to ships are costly to install. They are also prone to accidental damage, and subject to carelessness or overly protective attention. Moreover, it is difficult to control surface preparation, application, and climatic variables well enough to make a fair comparison between coating systems. Finally, they take so long that more promising materials are often available before the program is completed. This paper describes some of the proven techniques for simulating marine service and suggests their use to parallel more closely actual conditions that coatings encounter in marine service. The criterion for a good test is that it predict the order of performance of a number of coatings in the service for which they are intended. Proposed simulated service evaluation techniques must first be checked with coatings of known performance for that service. It is important that the coatings fail in laboratory studies in the same way as in actual service. Thus, the performance of new coatings can be related to the performance of the known coatings.

Chemical Degradation of the Silicone Rubber in Simulated PEMFC Environments

2011 ◽  
Vol 197-198 ◽  
pp. 741-748
Author(s):  
Guo Li ◽  
Jin Zhu Tan ◽  
Jian Ming Gong
Keyword(s):  
Fuel Cell ◽  
Surface Chemistry ◽  
Optical Microscopy ◽  
Silicone Rubber ◽  
Pem Fuel Cell ◽  
Sample Surface ◽  
Proton Exchange ◽  
Attenuated Total Reflection ◽  
Chemical Degradation ◽  
Over Time

The long term stability and durability of gaskets made of silicone rubber in proton exchange membrane fuel cell (PEMFC) has important effect on the sealing and the electric-chemical performance of the fuel cell. In present paper, the time-dependent chemical degradation of a silicone rubber was studied in three simulated PEMFC environments. The test temperature was selected and used at 90°C in this study according to the actual PEM fuel cell operation. Optical microscopy was used to show the topographical changes on the sample surface. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of the gasket material before and after exposure to the simulated PEM fuel cell environments over time. The results show that the weight loss increased with the exposure time for the samples. Optical microscopy reveals that the surface conditions of the samples changed over time from initially smooth to rough, crack appearance and finally crack propagation. The ATR-FTIR results show that the surface chemistry changed significantly via de-crosslinking and chain scission in the backbone for the material over time.

scholarly journals Ultrafast Laser Surface Texturing: A Sustainable Tool to Modify Wettability Properties of Marble

2019 ◽  
Vol 11 (15) ◽  
pp. 4079 ◽  
Author(s):  
Ana J. López ◽  
Alberto Ramil ◽  
José S. Pozo-Antonio ◽  
Teresa Rivas ◽  
Dolores Pereira
Keyword(s):  
Protective Coatings ◽  
Short Pulse ◽  
Surface Texturing ◽  
Water Vapor Permeability ◽  
Contact Angles ◽  
Toxic Waste ◽  
Laser Surface Texturing ◽  
Conservation Strategies ◽  
Vapor Permeability ◽  
Color Changes

Conservation strategies to reduce the degradation of stone caused by the action of water are focusing on increasing the hydrophobicity of the surface by imitating existing solutions in nature (lotus leafs and others). These are mainly based on the existence of hierarchical roughness with micro- and nanoscale structures. In the case of marble, research has focused on protective coatings that sometimes are dangerous for the health and the environment, and with undesirable effects such as color changes or reduction of water vapor permeability of the stone. Laser texturing, however, is an environmentally friendly technique, because no chemicals or toxic waste are added and, moreover, it can process nearly all types of materials. It has been used to change the surface texture of metals and other materials on a micro or even nanometric scale, to meet a specific functional requirement, such as hydrophobicity. The objective of this work was to analyze the feasibility of this technique to provide hydrophobic properties to a marble surface without appreciable changes in its appearance. Therefore, an analysis of the irradiation parameters with ultra-short-pulse laser was performed. Preliminary results demonstrate the ability of this technique to provide hydrophobic character the marble (contact angles well above 90 ∘ ). Besides, the analysis of the treated surfaces in terms of roughness, color and gloss indicates that changes in the appearance of the surface are minimal when properly selecting the process parameters.

Structure and Properties of Bisphenol a Polycarbonate Exposed to Ultraviolet

2013 ◽  
Vol 377 ◽  
pp. 255-260
Author(s):  
Yong Ge ◽  
Tao Wang ◽  
Yue Yan ◽  
Lei Li
Keyword(s):  
Bisphenol A ◽  
Light Transmission ◽  
Irradiation Time ◽  
Attenuated Total Reflection ◽  
Chemical Degradation ◽  
Surface Phenomenon ◽  
Exposed Surface ◽  
Structure And Properties ◽  
Bisphenol A Polycarbonate ◽  
Molecular Weights

In this study, the structure and properties of bisphenol A polycarbonate (BPA-PC) after UVB-313 radiation were investigated. When BPA-PC was exposed to ultraviolet (UV), this polymer showed two different degradation mechanisms: photo-Fries rearrangement and photo-oxidation. The interpretation of the observed chemical degradation was based on attenuated total reflection IR (ATR). Gel permeation chromatograph (GPC) measurements indicated that the molecular weights of exposed surface sample were decreased with increasing of irradiation time, but the molecular weights of bulk polymer did not decrease severely. Namely, the degradation of BPA-PC was a surface phenomenon, which only extended about several micrometers into the exposed surface. This also could explain why the mechanical properties of samples showed no change. In addition, photo-induced yellowing of the aged PC was aggravated with the irradiation time prolonging, but no remarkable changes of light transmission have been observed.

Some Notes on Artificial Aging Tests for Rubber

1930 ◽  
Vol 3 (1) ◽  
pp. 164-168
Author(s):  
W. W. Vogt
Keyword(s):  
Artificial Aging ◽  
Chemical Properties ◽  
Natural Aging ◽  
Point Of View ◽  
Aging Test ◽  
Sufficient Degree ◽  
Service Conditions ◽  
Physical And Chemical ◽  
Correlation Factors ◽  
And Chemical Properties

Abstract FROM a strictly quantitative point of view we should expect an artificial age test to duplicate in all respects the changes that take place on natural aging. In other words, all of the measurable physical and chemical properties should be changed in the same direction and to the same degree for all types of compounds. if we are looking for such performance from an artificial aging test, then in the writer's opinion none of the present tests fulfil these conditions to a sufficient degree to warrant any extensive use of correlation factors. It must, moreover, be realized that the present methods of artificial aging seek only to duplicate the natural aging of rubber on shelf storage in the dark. If we wish information that will predict aging of rubber products under their normal service conditions, then we must get into the field of specialized testing wherein the conditions with respect to light, temperature, humidity, etc., may be made to approach more nearly those of the actual service.

scholarly journals Protection of Steel Structures with Paint Coatings in the Context of Environmental Pollution

2021 ◽  
Vol 31 (2) ◽  
pp. 30-42
Author(s):  
Marek Henryk Dohojda ◽  
Beata Backiel-Brzozowska ◽  
Bożena Dohojda
Keyword(s):  
Environmental Pollution ◽  
Protective Coatings ◽  
Steel Structure ◽  
Steel Structures ◽  
Mechanical Action ◽  
Corrosion Products ◽  
Adjacent Area ◽  
Atmospheric Conditions ◽  
Paint Coatings ◽  
Corrosion Of Steel

Abstract The article presents important problems occurring in the operation of large-size steel structures protected by paint coatings. In our atmospheric conditions, corrosion of steel structures cannot be avoided, even with the use of protective coatings. The problem of environmental pollution with corrosion products and exfoliated paint then appears. When designing corrosion protection, durability of protection is assumed based on environmental corrosivity categories, but in practice degradation of paint coatings can occur much faster. The problem of premature peeling of paint results, among other things, from its faulty application and use. Steel structure repairs are usually carried out comprehensively, and new protection requires the removal of damaged coatings, mainly by sanding. As a result of the mechanical action of the abrasive material, old paints and corrosion products are removed, which results in a very large amount of waste that settles on the adjacent area. Due to the age of paint removed, this waste often contains compounds such as lead, chromium or zinc, which pose a real threat to the natural environment around the renovated buildings. In the article, based on the observations carried out directly on the exemplary structures in renovation, the actual scope of the waste emission was determined. This is a contribution to further spectrometric studies to determine the exact area of contamination and to identify heavy metals in the waste arising from the renovation of steel structures with paint coatings.

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