Doctor of Philosophy
Enhancing and recycling plastic are two important focuses in plastics research. In this dissertation, enhancing the property of polyetherimide (PEI) is first discussed, and two methods are introduced. Later, a new recycling strategy, the degradation-upcycling (Deg-Up) strategy, is presented. The potential of Deg-Up is evaluated on three plastics: polystyrene (PS), polyethylene (PE), and polypropylene (PP). These plastics serve broad applications in daily life, such as Styrofoam, food containers, shopping bags, garden decorations, and furniture.
PEI, a powerful plastic resilient to high temperature and strength, is broadly used in aerospace, defense technology, space exploration, and transportation. However, PEI can only be processed at high temperatures, and PEI films can be easily dissolved or compromised in many solvents, such as solmethine, chloroform, and furanidin. Water is not permeable in PEI, and therefore, it is strongly demanded to modify the PEI structure, giving PEI new and improved properties for water filtration and purification. We have investigated two methods for modifying PEI. Influencers affecting the PEI film's performance are also studied.
Plastic upcycling, which converts low-value wastes to high-value chemical products, is a vital technology that mitigates the environmental crisis and the plastic recycling problem. However, effective plastic upcycling improving waste value with good selectivity toward products with ten-fold or even greater value is uncommon due to the lack of upcycling theories/methodologies. This dissertation presents a new upcycling strategy; the degradation-upcycling strategy (Deg-Up) comprises degradation reactions yielding preliminary chemicals and upcycling reactions converting the preliminary chemicals to desired high-value products. Based on the Deg-Up strategy, PS is converted to fragrances and drug precursors, and PE and PP are Deg-Up to fats and soaps. The economic and industrial possibilities are also discussed through a preliminary industrial design and an economic analysis.