DIN EN ISO 29664:2017-05

This International Standard specifies methods to reproduce the weathering effects that occur when plastics are exposed to heavily polluted outdoor environments. Acidic precipitation can have a significant effect on the photochemical ageing of many polymers. In some cases, this is due to attack on the stabilizers or fillers like CaCO₃ applied in technical polymers. The mechanisms differ from those of harmful gases, which essentially constitute the initial products of acidic precipitation. Arising from changing industrial air pollution and additionally diffused by the stochastic wind and cloud distribution, acidic precipitation occurs sporadically. Thus, especially regarding acidic precipitation, outdoor weathering effects vary enormously within different years. Therefore, it is practically impossible to obtain reliable outdoor exposure results from just one season. These fluctuations can be avoided through the use of a laboratory test, where all weathering parameters, including the acidic deposition, can be controlled. In artificial weathering tests for plastics, the action of acidic atmospheric precipitation, which is part of the real world, has generally not been considered. This International Standard describes artificial weathering tests intended to evaluate plastics for use in heavily polluted outdoor environments. Results from this International Standard cannot be used to predict the service life of these plastics. This International Standard describes two different exposure methods. Use of the methods depends on the form of the plastic product being evaluated. Method A is intended for products where surface degradation is very important and uses a strong acid spray (pH 1,5) that is applied for a short time. Method B uses a weaker acid spray (pH 3,5) that is applied over a long period of time so that it can penetrate deeply into the product and is intended for products such as geotextiles and related products. This International Standard does not cover the influence of special chemicals like agrochemicals. The responsible German standardization committee is Working Committee NA 054-01-04 AA "Verhalten gegen Umwelteinflüsse" ("Environmental resistance") at DIN Standards Committee Plastics (FNK).