02/03/2026
By Danielle Fretwell

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Patrick Masembe on: "Energy‑Optimal Plastics Recycling: A Systems Framework Integrating Sorting Purity and Contamination‑Tolerant Pathways."

Candidate Name: Patrick Masembe
Degree: Doctoral
Defense Date: Wednesday, Feb. 11, 2026
Time: from 3 - 5 p.m.
Location: ETIC 445

Committee:

  • Advisor: Margaret Sobkowicz Kline, Professor (Assoc Chair), Plastics Engineering, University of Massachusetts Lowell
  • Amir Ameli, Associate Professor, Plastics Engineering, University of Massachusetts Lowell
  • Christopher Hansen, Professor (Chair), Mechanical & Industrial Engineering, University of Massachusetts Lowell
  • Davide Masato, Associate Professor, Plastics Engineering, University of Massachusetts Lowell

Abstract:
This research reframes plastics recycling around energy optimization instead of the traditional purity-based model. Increasing sorting requirements raise both energy use and costs, which restricts mechanical recycling and sends mixed or contaminated plastics to more energy-intensive processes. This work proposes that tolerating contamination and engineering value into mixed feedstocks can reduce total system energy while expanding viable recycling pathways.

Preliminary studies show the potential of this approach. PET composites intentionally formulated with cellulosic contaminants retained functionality when processing conditions were optimized. Machine-learning analysis of commingled polyolefins exposed misclassification that can be corrected through targeted compatibilization. Catalytic reactive extrusion also reduced the thermal degradation temperature of polyolefin streams, indicating lower energy demand for downstream pyrolysis.

Building on these results, the dissertation will develop a quantitative framework that links sorting intensity, feedstock composition, embodied energy, and process performance. The framework will identify conditions under which direct reprocessing, compatibilization-enabled recycling, or catalytic reactive-extrusion-assisted pyrolysis provide the lowest energy use. The resulting decision-support tool aims to guide recycling system design toward minimizing total energy demand and enabling more circular and resilient plastics recovery.