02/05/2026
By Danielle Fretwell

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Patrick Casey on: "Modeling, Surrogate Simulation, & Validation of Sonicated-Assisted Extrusion & Recycling Multilayer Films Via Melt Separation."

Candidate Name: Patrick Casey
Degree: Doctoral
Defense Date: Wednesday, Feb. 11, 2026
Time: 11 a.m. - 1 p.m.
Location: Ball Hall, Room 302

Committee:

  • Advisor: David Kazmer, Ph.D., Professor, Plastics Engineering, University of Massachusetts Lowell
  • Margaret Sobkowicz-Kline, Ph.D., Professor, Plastics Engineering, University of Massachusetts Lowell
  • Jay Park, Associate Professor, Ph.D., Plastics Engineering, University of Massachusetts Lowell
  • Carter Keough, Assistant Teaching Professor, Ph.D., Mechanical & Industrial Engineering, University of Massachusetts Lowell

Brief Abstract:
Polyolefin packaging commonly uses barrier layers to protect contents from oxygen, oils, and UV light, which can shorten shelf life, discolor product contents and distort taste. This is typically done through multi-layer extrusion, where each layer serves a specific purpose. However, some layers do not bond well with each other. To address this, “tie” layers made from different materials are added, commonly maleic anhydride (MAH). Although purpose built, these melded layers make recycling this packaging more difficult at the end of its life. Enhancing crystallinity is critical in reducing the number of layers needed for packaging and ease recycling streams. Crystalline morphology plays a key role as gas diffusion is effective only in the amorphous regions. An advantage to increased crystallinity is the reduction of oxygen permeation, mechanical properties, and thermal behavior. This research investigates sonication-assisted extrusion as motivated by a detailed review of the literature that underscores the potential of ultrasonication to enhance polymer processing by improving shear mixing, filler dispersion, and crystallization kinetics.

In alignment with these processing goals, this research evaluates a specific material system that is used for many multilayer packaging films: low-density polyethylene (LDPE) acting as the outer layers and a polyvinyl alcohol (PVOH) center acting as the barrier layer. Separating these layers is incredibly difficult which leads to problematic recycling streams, increased landfill content or incinerator fuel. LDPE can be melt processable as low as 135°C and PVOH processing at 180°C allowing for an opportunity to suspend the PVOH in molten LDPE. Initial laboratory trials using a high-pressure filter, and a compression molder with heated platens have shown a proof of concept that the two materials can be separated. Continued research aims to melt-separate LDPE and PVOH using the mechanical action of a single screw extruder and a custom die to filter the PVOH media in a way similarly used to screen contaminants. Separating the two materials into different streams increases recyclability and can recapture the PVOH to be recycled through dissolution recovery.