03/25/2025
By Danielle Fretwell
The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation defense by Mansoureh Jamalzadeh on "Field-Assisted Extrusion Processing for Multi-layer Film Recycling."
Date: Friday, April 4, 2025
Time: 11 a.m. -1 p.m.
Location: Emerging Technologies and Information Center 445
Committee:
Advisor: Margaret J. Sobkowicz-Kline, Ph.D., Professor, Plastics Engineering, UMass Lowell
Committee Members*
David Kazmer, Ph.D., Professor, Plastics Engineering, UMass Lowell
Amir Ameli, Ph.D., Associate Professor, Plastics Engineering, UMass Lowell
Marina Ruths, Ph.D., Professor, Chemistry, UMass Lowell
Abstract:
Multilayered polymer-based films present significant challenges in recycling due to their heterogeneous composition. Often, these films are downcycled, landfilled or incinerated because separating the different layers for mechanical or chemical recycling is difficult. This issue can be resolved by incorporating an external field during the extrusion process, rather than relying on specialized polymer formulations or additives. This approach is more versatile and can result in high-performance films that are inherently recyclable.
For heterogeneous recycled polymer blends, irradiation-assisted reactive extrusion can enhance the compatibility of immiscible polymers without the need for designer chemicals. However, the effects of ionizing radiation on polymers depend on factors such as polymer structure, environmental conditions and irradiation dose and detailed studies are necessary to optimize this technique for specific polymer materials and recycling purposes. Another approach is ultrasonic-assisted extrusion, which can improve the barrier properties of polyethylene films by accelerating crystallinity and altering the crystal structure without adding additional polymer layers. This technique involves high-frequency ultrasonic vibrations of the molten polymer, which can produce polyolefins suitable for various applications. By employing ultrasonic-assisted processing, a significant reduction in the number of polymer layers that hinder the recyclability of flexible packaging can be achieved, thereby enhancing the sustainability of the packaging industry.
This research investigates two extrusion approaches to recover value from flexible films and mixed plastic packaging waste streams, which present significant challenges to recycling. The application of gamma irradiation to induce interfacial reactions was examined regarding the compatibility of polyethylene terephthalate (PET) and low-density polyethylene (LLDPE) blends, as these polymers are frequently used in multilayered food packaging. Furthermore, using ultrasonic fields during the continuous film extrusion process was explored to modify the crystal structure of monolayer polyethylene films, thus enhancing their oxygen barrier. The ultrasonic-assisted extrusion underscores design for recycling, removing the need for multilayer films. In contrast, the irradiation-assisted reactive extrusion prioritizes compatibilization when multilayer or multicomponent materials enter the waste stream.