## 2 Materials and Methods
### Definition of the Degradation Testing Conditions  
One degradation cycle lasted 24 h, and 60 cycles were performed. Organic coatings are tested for 30 days as a standard. In these cases, however, the coating is applied, for example, to an inorganic zinc coating or directly to a steel substrate [38; 39; 40].  
However, immediately after the perforation of the protective coating on the zinc or steel substrate, corrosion products are formed. These corrosion products increase in volume, resulting in blistering and the subsequent delamination of the coating. However, this type of degradation mechanism is excluded in the case of the tested polymer materials. For this reason, the degradation cycle was extended to double the normal standard. The experiment began in a salt fog environment, a Liebisch corrosion chamber, type S400M-TR (Bielefeld, Germany), was used for this purpose. The suspension of the samples was carried out on silicone rods with the help of a silicone line.  
Test parameters:  
* Temperature in the salt fog environment: 20 \(\pm\) 2 \({}^{\circ}\)C;
* Concentration of the sodium chloride solution in distilled water: 50 \(\pm\) 5 g: L\({}^{-1}\);
* pH value of the sodium chloride solution: 6.5-7.2 (at a temperature of 20 \(\pm\) 2 \({}^{\circ}\)C);
* Air pressure supplied to the spray nozzles: 120 kPa;
* Constant 100% relative humidity (continuous spraying of salt solution);
* Exposure time: 10 h.  
The exposure in the salt fog was followed by a transfer for 14 h to the climatic chamber (ClimeEvent 2, Reiskirchen, Germany--With a volume of approximately 400 L). Here, 10% relative humidity (the lowest possible) was chosen. A degradation cycle based on alternating temperatures above the freezing point, accompanied by high relative humidity, and temperatures below the freezing point, associated with low relative humidity, is also presented, for example, in the publication [16].  
Due to the elimination of sudden changes in temperature or in order to simulate real natural conditions, the samples were placed in the climatic chamber at a temperature of 5 \(\pm\) 1 \({}^{\circ}\)C. After that, there was a smooth (linear) cooling below the freezing point to a temperature of \(-\)20 \(\pm\) 1 \({}^{\circ}\)C, which lasted approximately 4 h on average.  
Exposure of the samples at this temperature lasted another 6 h. Next, there was a smooth (linear) increase in temperature, namely to the original 5 \(\pm\) 1 \({}^{\circ}\)C (duration of approximately 4 h again). This was followed by moving the samples back into the salt fog environment (constant temperature 20 \(\pm\) 2 \({}^{\circ}\)C).  
Without this continuous cooling/thawing, there would be a risk of the protective coatings shrinking/expanding too quickly, while in the case of the polymer substrate, the temperature would still be very close to the previous environment. This thermal shock would probably cause delamination of the coatings, but it would occur under unrealistic natural conditions, which are not the subject of this experiment. The mentioned time intervals also correspond with the degradation cycle mentioned in the publication [17]. Dueto the simulation of the degradation of fasteners used on the car chassis, the degradation of samples by UV radiation will not be part of the experiment.