Material recycling is a method of maintaining the polymer state of plastics, melting and dissolving them, and then processing them into new products. Compared with petrochemical-derived plastics, biodegradable plastics should also be reused multiple times, and then recycled. The difficulty in material recycling lies in the mixing of dissimilar polymers and additives, and the mixing of partially hydrolyzed polymers.
Biodegradable plastics are the same as general-purpose plastics such as PET. After collection, they must undergo pre-treatments such as separation, selection, and crushing of impurities, and then melt and pelletize. Generally, according to different uses of plastics, the performance requirements are also different. Therefore, due to the reasons mentioned above, the performance of the plastic obtained from material recycling will be reduced, and it can no longer be used for the same purpose, and can only be used in a downgrade.
Therefore, following the method of material recycling, chemical recycling must be considered. The popularity of biodegradable plastics is still very limited, so recycling is also restricted. For example, the food utensils used at the 2005 Aichi World Expo in Japan, as an example of material recycling, are recycled into plant cultivation containers for use in Okayama National Sports, which opened in October of the same year.
In actual use, in order to improve the strength, heat resistance and other properties, various additives and mixed solvents are mixed into PLA. For example, by mixing kenaf fiber into the housing of electrical appliances and auto parts, a resin with sufficient strength and heat resistance can be obtained. Kenaf itself grows very fast and has a large amount of fixed carbon dioxide, but it is rarely used as a plant fiber and is expected to be used as a bio-based fiber. The basic process of material recycling of PLA added with kenaf plant fiber is melting, pelletizing and reshaping. There will be no significant decrease in physical properties during the process, so it can be recycled multiple times.
However, with the gradual increase in the variety and use of bioplastics in the future, more and more of them need to be recycled. Material recycling alone is obviously impossible to handle, so chemical recycling and reuse are gradually ignored.