*3.4. Coating Gloss Loss Study*

The weathering aging causes the degradation in properties of the coating. Hence, the degradation of the coating under the weathering factors can be evaluated by monitoring the variations in their properties. Figure 7 demonstrates the variations in gloss of the ACPU, ACPU/SiO2, and ACPU/SiO2-T coatings during aging process. Besides, as the reference, we added the gloss changes of ACPU-T coating [3] into Figure 7.

From Figure 7, it can be seen that the gloss of the coatings decreased by aging time. The gloss of the neat coating was lost significantly. The gloss of the nanocomposite coating containing light stabilizer, by contrast, was lost slightly. After 36 aging cycles, the gloss value of the ACPU, ACPU/SiO2, and ACPU/SiO2-T coatings, remained at 83.3%, 92.5%, and 98.5%, respectively. For comparative study, the gloss change in ACPU/SiO2-T coating was lower than that in ACPU-T coating.

**Figure 7.** Changes in gloss of the coatings under accelerated weathering aging condition.
