08/11/2025
By Kwok Fan Chow

The Kennedy College of Science, Department of Chemistry, invites you to attend a Ph.D. Research Proposal defense by Kalsoom Jan entitled “Advancing Chemical Recycling Pathways for Polyethylene and Multilayer Plastics via Hydrothermal and Chemolytic Deconstruction Strategies.”

Degree: Doctoral
Location: ETIC, Room 445
Date: Tuesday, Sept. 2, 2025
Time: 3 p.m.

Committee Chair:

  • Advisor Wan-Ting (Grace) Chen, Plastics Engineering Department, University of Massachusetts Lowell
  • James Reuther, Department of Chemistry, University of Massachusetts Lowell
  • Michael Ross, Department of Chemistry, University of Massachusetts Lowell
  • Hsi-Wu Wong, Department of Chemical Engineering, University of Massachusetts Lowell
  • YuanQiao Rao, Dow Chemical Company, Dow Chemical Company
  • Marina Ruths, Department of Chemistry, University of Massachusetts Lowell

Abstract:
The increasing accumulation of plastic waste, especially from multilayer packaging, heterogeneous mixed plastic materials, and contaminated streams, poses major challenges to plastics recycling. This dissertation explores advanced and integrated chemical recycling strategies to valorize plastic waste using hydrothermal liquefaction (HTL) and chemolysis, supported by quantum mechanical methods. First, the role of calcium carbonate (CaCO3), a common contaminant, on HTL of polyethylene (PE) was examined. It was found that CaCO3 influenced the HTL product distribution. Additionally, over 90% calcium was removed into the aqueous phase during HTL, while the oil yields reached at 80%. Secondly, the co-liquefaction of PE with polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and ethylene vinyl alcohol (EVOH) was studied to simulate mixed plastics waste (e.g., multilayer packaging waste). The non-PE, more labile polymers appear to promote deconstruction of recalcitrant PE under HTL, while altering product compositions. For example, adding PS enhanced the oil yields converted from the PS/PE blends by 67% and shifted oil products toward aromatics by 82%. Lastly, a two-step chemolytic approach was developed for multilayer laminated packaging films, involving acidolysis-based delamination followed by catalytic glycolysis of PET. Two catalysts, zinc and calcium acetate, were used and showed distinct product selectivity towards BHET and MHET, respectively. The hydration state of the catalyst also dictates the product selectivity of PET catalytic glycolysis. This work is expected to contribute to developing efficient, robust, and cost-effective chemical recycling strategies for complex plastic waste streams.

All interested students and faculty members are invited to attend.