"Accelerated weathering". The need of OEMs / Deepak Shanbhag in PAINTINDIA, Vol. LXII, N° 1 (01/2012)

[article]  inPAINTINDIA > Vol. LXII, N° 1 (01/2012) . - p. 98-105 Titre : "Accelerated weathering". The need of OEMs Type de document : texte imprimé Auteurs : Deepak Shanbhag, Auteur Année de publication : 2012 Article en page(s) : p. 98-105 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Automotile -- Peinture -- Détérioration Electrochimie Essais accélérés (technologie) Résistance à l'humidité Résistance au rayonnement ultraviolet Revêtements -- Effets du climat Spectroscopie d'impédance électrochimique Index. décimale : 667.9 Revêtements et enduits Résumé : One of the most important pre-requisite for exterior automotive coatings is longevity. The ability to predict longevity, or service life, is key to developing new automotive coating technologies for the original equipment manufacturers (OEMs). While exposure testing is performed in natural field environments such as Florida, it is not cost or time efficient to solely use these results for automotive coating development. Performance, as applied to paint systems, can be defined broadly as resistance to their environment, the latter covering all types of exposure conditions. In respect of the paint systems, the two most destructive influences are sunlight and moisture. The crucial test for any paint used on an exterior surface is the durability or resistance to an environment comprising weather and location. Weather consists of several factors - sunshine, rain, acid rain, temperature, fog, frost, atmospheric pollution and to a lesser extent wind. The influence of these weather factors on coated surfaces are studied in weathering tests. In order to speed up the product development process in automotive paint manufacturing industries, accelerated weathering tests are used to predict the longevity of the coating technologies in a fraction of the time that would be required for a field test. The acceleration factors can be as fast as 10 times, i.e., getting the equivalent of 10 years worth of field testing in one year of accelerated testing. There are a number of accelerated tests used, including QUV, salt spray, acid etch test, filiform corrosion, cyclic corrosion, weather-ometer (WOM), etc. Apart from these older tests, there are novel electrochemical methods such as electrochemical impedance spectroscopy (EIS) and electrochemical noise method (ENM). While there are many tests than can predict defects with good field correlation, there are other areas where correlation has been difficult. This review paper focuses on studying the various accelerated tests available till date and points, out their benefits and the improvements required so taht these accelerated tests resemble thenatural exposure effects. Note de contenu : - Corrosion evaluation using electrochemical techniques - Natural weathering by sunlight - Corrosion weathering resistance - Weatherometer - Improvements required intensity and distribution of light - Water - pH Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=13819 [article]

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Modeling of molecular weight of acrylic resins using full factorial techniques / Nishant N. Prabhu in PAINTINDIA, Vol. LIX, N° 4 (04/2009)

[article]  inPAINTINDIA > Vol. LIX, N° 4 (04/2009) . - p. 53-64 Titre : Modeling of molecular weight of acrylic resins using full factorial techniques Type de document : texte imprimé Auteurs : Nishant N. Prabhu, Auteur ; Deepak Shanbhag, Auteur Année de publication : 2009 Article en page(s) : p. 53-64 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 667.9 Revêtements et enduits Résumé : Initiator half life at the processing temperature, initiator concentration and monomer feed rate are the factors governing the molecular weight and the viscosity properties of an acrylic resin in "drip-feed" process. Contribution of each of these factors on the molecular weight of the polymer was determined using full factorial analysis. Twelve resin batches were processed as per the statistical design of experiments. The molecular weight distribution of these acrylic resins were recorded by GPC. The data was analysed by full factorial analysis. A mathematical equation was obtained correlating the molecular weight of the polymer with the levels which these three parameters are set during the processing. Using this mathematical equation, the molecular wight was predicted for a batch where these parameters were set at particular values. The batch was processed and its molecular weight was determined by GPC. The observed value was found to be in good agreement with the value predicted by the equation. Thus, this statistical tool can be used for predicting the molecular weight of the polymer from the set parameters. The parameters can now be set based on other consideration such as energy consumption, cost of formulation and cycle time and molecular weight can be predicted using the equation. The parameters can be further finetuned using the equation to get desired molecular weight thus eliminating the requirement of processing of large number of batches. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=6788 [article]

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