## 5 Test Results
### Ageing Tests  
Table 4 presents the average gloss measurement results for the samples made from the three-ply laminate before and after the ageing tests, together with the calculated gloss loss. Figure 6: Samples mounted in the device during UV resistance testing. The average gloss before the solar and UVB resistance tests oscillates around 90 GU. From the calculated results, a significant loss of gloss after the sun fastness test of approximately 34% can be observed. After the UVB test, the gloss decreased to an average value of approx. 11.6 GU, i.e., a loss of gloss of approximately 87%. The appearance of the outer surface of the laminate after the UVB test is presented in Figure 7. Localised dulling, in the form of small matte patches, can be seen on the test samples (marked with a white box in the figures). Gloss measurements showed that, in addition to the visible tarnishes, the overall gloss was also reduced. The appearance of the structure after the UVB light resistance test is presented in Figure 8. In addition, the colour change according to the grey scale was determined. The colour change according to the grey scale for all the samples tested was 1/2. The clear tarnishing of the samples over the entire area under magnification is shown in Figure 9. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ageing Test** & **Medium Gloss before Test GU** & **Medium Gloss after Test GU** & **Loss of Gloss \%** \\ \hline The solar resistance test & \(90.99\pm 1.31\) & \(60.49\pm 2.79\) & 33.52 \\ \hline UVB resistance test & \(89.84\pm 1.61\) & \(11.66\pm 1.01\) & 86.99 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Gloss measurement results. Figure 8: Example of sample after UVB resistance test. Figure 7: Structure of the sample after the sunlight resistance test; magnification \(20\times\). Hardness measurements by the ball-and-socket method on the tested three-ply laminate were carried out only on samples after sunlight ageing. The results showed that, despite visible changes in the surface of the composite, the structure itself had strengthened and hardened (Table 5). The hardness (H) compared to the unaged sample increased by about 38 N/mm\({}^{2}\), i.e., by about 25%. The specimens after both ageing tests were additionally subjected to static tensile and bending tests according to method-specific test procedures. The static tensile test results for the three-ply laminate before and after the ageing tests are shown in Table 6.  
The average tensile stress value for the three-layer sheet is 358.28 \(\pm\) 19.7 MPa. After the solar resistance ageing test, this value increased by approximately 4% (to a value of 371.4 \(\pm\) 31.7 MPa) compared to the sample before ageing. After the UVB light resistance test, the value decreased by approximately 29% relative to the unaged three-ply laminate specimens. Figure 10 shows examples of static tensile test plots for an example specimen from each series. The sample whose graph was closest to the average values obtained was selected. \begin{table}
\begin{tabular}{c c c c} \hline
**Type of Specim** & **Fracture Force N** & **Relative Elongation \%** & **Tensile Stress MPa** \\ \hline three-ply & 3693.97 \(\pm\) 227.3 & 4.12 \(\pm\) 0.3 & 358.28 \(\pm\) 19.7 \\ \hline three-ply after XWO ageing & 3826.29\(\pm\) 171.9 & 3.54 \(\pm\) 0.3 & 371.40 \(\pm\) 31.7 \\ \hline three-ply after UVB ageing & 2759.55 \(\pm\) 259.6 & 3.00 \(\pm\) 0.5 & 360.34 \(\pm\) 13.4 \\ \hline \end{tabular}
\end{table} 
Table 6: Tensile test results for three-ply laminate before and after ageing tests. \begin{table}
\begin{tabular}{c c c} \hline
**Type of Specim** & **Imprint Depth mm** &
\begin{tabular}{c} **Hardness by Ball Pressure** \\ **Method N/mm\({}^{2}\)** \\ \end{tabular} \\ \hline three-ply & 0.165 \(\pm\) 0.011 & 154.35 \(\pm\) 12.85 \\ \hline three-ply after XWO ageing & 0.179 \(\pm\) 0.010 & 192.24 \(\pm\) 9.66 \\ \hline \end{tabular}
\end{table} 
Table 5: Results of hardness measurements by ball method for three-ply laminate before and after ageing.