## 3 Results and Discussion
### Influence of Coating Processes on the Performances of Waterborne Coatings Containing Microcapsules
#### 3.2.4 Analysis of Microstructure and Infrared Spectrum of Coatings
Even if the microcracks occur in the high-temperature environment, the microcracks will cause the microcapsule wall in the coating to break, and the core material will flow out and solidify at the crack, so as to inhibit or reduce the expansion of cracks and damage. However, the coating without microcapsules is prone to produce the cracks, and the cracks will continue to expand under the continuous action of environmental factors. It is directly proved that microcapsules can improve the aging resistance and thermal stability of waterborne coatings. Figure 11: Effect of time on light loss rate of coating in UV weather resistance test. Figure 12: SEM images of coating without and with microcapsules after aging at 120 \({}^{\circ}\)C in oven: (**A**) without microcapsules, (**B**) with 6.0% microcapsules. The change of chemical composition of waterborne coatings without microcapsules before and after aging tests can be observed in Figure 15. The characteristic absorption peaks of methyl and methylene are at 2943 cm\({}^{-1}\) and 2875 cm\({}^{-1}\). The characteristic absorption peak of -OH is at 1731 cm\({}^{-1}\), and the characteristic absorption peak of carbon oxygen single bond in ester group is at 1166 cm\({}^{-1}\). The chemical composition of the waterborne coating before and after aging does not change, indicating that the aging test will not cause chemical reaction of the coating. Figure 16 is the infrared spectrum of the coating with 6.0% microcapsule before and after aging. It is observed that the characteristic peak positions are basically the same and the chemical composition has no change, indicating that there is no chemical reaction before and after the aging resistance test of the coating with 6.0% microcapsules. Figure 5:0 SEM images of coating without and with microcapsules after aging in UV weather resistance test: (**A**) without microcapsules, (**B**) with 6.0% microcapsules. Figure 5:1 SEM images of coating without and with microcapsules after aging at 160 \({}^{\circ}\)C in oven: (**A**) without microcapsules, (**B**) with 6.0% microcapsules. The stability and aging resistance of shellac microcapsules coated with 6.0% melamine/rice husk powder were compared with those without microcapsules. The results show that the composition of the coating does not change under any aging condition. In the aging test, the chromatic aberration of the coating will gradually increase with time. The chromatic aberration and light loss rate of the coating without microcapsule change more than that with microcapsule. The coatings without microcapsules have the large size damage, while the coatings with 6.0% microcapsules have much less damage in diameter and quantity. It indicates that the addition of microcapsules will make the coating have better stability and aging resistance. The coating with 6.0% microcapsule has good stability and aging resistance, indicating that a melamine/rice husk powder coated shellac microcapsule can inhibit the generation of microcracks and repair the coating to a certain extent.