10/30/2026
By Marley O'Neil
The Francis College of Engineering's Department of Plastics Engineering invites you to attend a doctoral dissertation proposal defense by Evan Yu titled “Advanced Chemical Techniques for Challenging-to-Recycle Polymer Wastes and Their Technoeconomic Viability.”
Details
- Date: Wednesday, Nov. 4, 2026
- Time: 10 a.m. – Noon
- Location: ETIC 445
Committee
- Advisor: Grace Chen, associate professor, Department of Plastics Engineering, UMass Lowell
- Margaret Sobkowicz Kline, professor, Department of Plastics Engineering, UMass Lowell
- Hsi-Wu Wong, professor, Department of Chemical Engineering, UMass Lowell
- Akshay Kokil, associate teaching professor, Department of Plastics Engineering, UMass Lowell
- Anthony Kotula, staff scientist, National Institute of Standards and Technology
Abstract
The widespread integration of polymeric materials into society has resulted in the widespread accumulation of plastic waste worldwide. Mechanical recycling has proven viable at a large scale for handling large-volume commodity polymers such as rigid polyethylene and polypropylene. However, the technology struggles with heavily contaminated waste streams and is incompatible with many multi-material components or non-rigid polymer morphologies. Chemical methods such as solvent-based processes or thermochemical recycling — i.e., pyrolysis and hydrothermal liquefaction (HTL) — offer potential alternative pathways toward dealing with these more complex polymer materials. This Ph.D. dissertation research aims to help develop chemical techniques to improve the sustainable usage of complex plastic streams. Chapter 3 focuses on the exploration of a solvent-based colorant removal process for the valorization of colored polycarbonate wastes. An initial screening identifies the most promising solvents in terms of color-removal performance and recovery yield. The effects of temperature and solvent reuse are also evaluated, as are the molecular weight and tensile properties of recovered feedstock. Chapter 4 first relates to the characterization of municipal solid waste (MSW) plastics on a national scale. Samples are hand-sorted to identify the major polymeric fractions before ash content and inorganic composition analysis are carried out. Estimated activation energies are also obtained through thermogravimetric analysis (TGA). Subsequently, thermochemical recycling, with HTL as the primary focus, is investigated as a potential conversion pathway for MSW plastics into valuable fuels and chemicals. Samples with varying polymeric composition, inorganic contents and activation energies will be down-selected and run under supercritical conditions to evaluate their effect, if any, on product yields and oil product composition. A select number of samples will also be subjected to pyrolysis for comparison. Chapter 5 studies the use of HTL at subcritical conditions for the deconstruction of PC/ABS blended plastic used in medical devices. In particular, the reaction conditions will be selected such that the recovery of bisphenol A (BPA) can be maximized while leaving behind ABS in solid form. Different PC/ABS blend ratios will be tested to understand any synergistic effects between PC and ABS during the reaction. Lastly, Chapter 6 investigates the technoeconomics of hydrothermal processing for the conversion of multilayer film waste into benzene, toluene, ethylbenzene and xylene (BTEX) as the target product. Using Aspen Plus, a simulated continuous HTL and separation process diagram is developed and analyzed at various reaction conditions based on lab-scale experimental data to obtain key economic metrics of capital expenditure (CAPEX), operational expenditure (OPEX) and minimum selling price (MSP). The effect of process capacity on economic metrics will also be investigated.