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The formation, dissociation, and reformation of cyclopentane (CP) hydrate in a sub-millimeter-sized capillary were conducted in this work, and the morphology of CP hydrate was obtained during above processes, respectively. The influences of the supercooling degree, i.e., the hydrate formation driving force, on CP hydrate crystals’ aspect and growth rate were also investigated. The results demonstrate that CP forms hydrate with the water melting from ice at the interface between the CP and melting water at a temperature slightly above 273.15 K. With the action of hydrate memory effect, the CP hydrate in the capillary starts forming at the CP-water interface or CP–water–capillary three-phase junction and grows around the CP–water interface. The appearance and growth rate of CP hydrate are greatly influenced by the supercooling degree. It indicates that CP hydrate has a high aggregation degree and good regularity at a high supercooling degree (or a low formation temperature). The growth rate of CP hydrate crystals greatly increases with the supercooling degree. Consequently, the temperature has a significant influence on the formation of CP hydrate in the capillary. That means the features of CP hydrate crystals in a quiescent system could be determined and controlled by the temperature setting.

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The individual organic or inorganic ultraviolet absorbers contain absorption bands in different wavelength regions below 400nm, and the coupling of the two types of absorbers can improve anti-aging properties of coatings to prolong the service lifetime. Nanosized rutile and two typical commercial organic ultraviolet absorbers 2 - hydroxyl - 4 - n - octyloxybenzophenone (UV-531) and 2 - (3 - tert - butyl - 2 - hydroxyl - 5 - methylphenyl) - 5 - chloro - 2H - benzotriazole (UV-326) were coupled. Optical property of the hybrid ultraviolet (UV) absorbers was measured by UV-vis. The anti-aging property of polyacrylate coatings added with UV absorbers was carried out in a weatherometer and investigated by chalking and FTIR. The results show that hybrid UV absorbers have better performances of UV absorption with synergistic effects than both organic and inorganic components. In addition to improving the protection against UV, the coatings properties of adhesive, pencil hardness and stain resistance were increased by adding hybrid UV absorbers. The anti-aging mechanism of UV absorbers was analyzed.

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