Purification of water through oil–water separation is essential for preserving the ecosystem and protecting human health. Although a conventional polypropylene depth filter can effectively purify water, modifying the wettability of a filter for oil–water separation is difficult owing to its low reactivity. In this study, we developed a superhydrophilic polypropylene filter with a hydrogel layer that could enable effective oil–water separation by using plasma treatment and dip coating, which enabled an even distribution of the coating solution across the filter. The fabricated filter was superhydrophilic with a water contact angle of 0o. It showed a high repulsive force with oil in water with an underwater oil contact angle of 142.9o. When such filter was applied to an oil–water separation device, it effectively purified water with low oil content (< 15 ppm) at a flow rate of 300 mL/min. These results demonstrate potential applications of such filters in areas such as wastewater treatment and oil spill cleanup.

A small wind power generator with Archimedes blades made of polypropylene has been developed for the effective generation of eco-friendly electronic energy. Despite the excellent structural characteristics of the higher performance of an Archimedes blade, its shape is complicated to manufacture, and presents difficulty in guaranteeing mechanical reliability in the outdoor operating environment. Especially, the UV-Light deterioration in a long-term of several years affects the mechanical properties of the polypropylene blade. To evaluate the change of strength depending on the amount of UV-Light irradiation in the outdoor environment, an accelerated UV-Light deterioration test is proposed and conducted using three types of blade materials, such as polypropylene with UV-Resistance material (C₂₀ H₂₅ N₃O) coated and mixed ones. Through the experimental tests, the UV resistant material coating on the blade showed the best properties for long-term exposure to UV light. Based on the test results of property changes, the Archimedes blade was analyzed using a finite element method to predict the reliability of the blade’s underused conditions. As a result of the analysis, the UV degradation resistance of Archimedes blades with UV coating improved by 2.4 times compared to the case without UV coating.

The heat-sealing strength of pouch film greatly affects the reliability of the lithium ion secondary battery. In this paper, the researchers investigated and evaluated the properties of the heat-sealing strength of pouch film, such as heat, pressure, time, thickness of the heat-seal, and the polypropylene material. The heat-sealing strength showed a high value at 180℃ for 3 seconds. However, under the conditions of higher temperatures and longer times, deformation and bulging of polypropylene were observed. The heat-sealing strength tended to increase when decreasing heat-seal thickness. The heat-sealing strength varied according to the type of polypropylene. In addition, to avoid defects that may have occurred in the process of manufacturing the lithium ion secondary battery, the heat-sealing strength in the state where the impurities remained was evaluated.