In order to develop a new use for surplus agricultural resources, the Fisheries Research Institute, Council of Agriculture, introduced oyster shells into biodegradable materials (such as PBS) and successfully developed oyster shell/PBS biological materials. This new material can replace up to 20% of PBS raw materials, effectively reduces manufacturing costs and significantly eliminates waste oyster shells. Moreover, it helps to achieve the goal of environmental friendliness, recycling, and waste reduction in response to the development trend of levying plastic product taxes around the world in the future.
The Fisheries Research Institute pointed out that most traditional plastic products, such as PS, PP, PE, and PVC, are dumped in refuse tips or scattered in the surrounding environment and flow into the ocean after use, and because they are non-biodegradable, the plastic particles (plastic particles with a diameter of less than 5 mm) of traditional plastic products are prone to cause marine pollution. In addition, the greenhouse gases generated during the manufacturing and incineration of plastics cause a large amount of carbon emissions, which seriously threatens the realization of the climate goal of "controlling the global average temperature rise within 1.5℃", as set by the Paris Agreement in 2015.
According to the Fisheries Research Institute, after the composting process under specific conditions, biodegradable materials can be decomposed by microorganisms into inorganic compounds, such as carbon dioxide and water, which can be absorbed by plants and ultimately return to nature. The Institute introduced oyster shells into biodegradable materials, such as PBS, and produced oyster shell/PBS composite materials that have mechanical properties comparable to those of commercially available PBS, meaning they can be molded into biodegradable lunch boxes, bowls, and plates by injection molding. Moreover, it was found that the addition of oyster shells could effectively improve the thermal stability of the materials. In the heavy metal dissolution test, the oyster shell/PBS composite materials also met the sanitation standards for food-grade utensils, containers, and packages. After 45 days of composting treatment (at a standard operating temperature of 58 ± 2℃), the disintegration degree of the composite materials can reach 95.1%, indicating that it has considerably good disintegration ability and decomposability. In addition, the Fisheries Research Institute has successfully introduced oyster shells into polyester products, such as PBAT and PBSA, to develop biodegradable material sources. In the future, oyster shells can be applied to food containers, packaging, and agricultural materials based on the characteristics of different raw materials, showing great potential for commercial development.
Figure 1. Oyster Shell/PBS Biodegradable Dining Sets (Lunch Boxes, Bowls, and Plates)