08/13/2025
By Danielle Fretwell

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Milad Azami on: "Fracture resistance of 3D printed sustainable PLA blends and nanocomposites."

Candidate Name: Milad Azami
Degree: Doctoral
Defense Date: Thursday, Aug. 28, 2025
Time: 10 a.m. - noon
Location: ETIC 445

Committee:

  • Advisor: Amir Ameli, Associate Professor, Plastics Engineering, University of Massachusetts Lowell
  • Davide Masato, Associate Professor, Plastics Engineering, University of Massachusetts Lowell
  • Jay Park, Associate Professor, Plastics Engineering, University of Massachusetts Lowell
  • Siva Nadimpalli Associate Professor Mechanical Engineering, Michigan State University

Brief Abstract:
Environmental concerns over plastic waste have driven interest in sustainable, biodegradable polymers like polylactic acid (PLA). Although PLA offers good strength and stiffness, its brittleness limits its applicability. The brittleness of PLA can be improved by blending it with more ductile polymers such as polybutylene succinate (PBS) or polyhydroxyalkanoate (PHA). Additionally, biodegradable polymers come with some processing challenges, such as being shear- and heat-sensitive and their immiscibility. These characteristics make them prone to process-induced degradation and can lead to limitations in their load bearing properties. This work first aims to better understand the process related challenges of PLA blends by evaluating how different compounding methods- masterbatch dilution versus direct dry blending- affect the thermal, mechanical, and morphological properties of PLA/PBS and PLA/PHA blends. It also aims to identify optimal blend compositions that demonstrate improved mechanical performance compared to pure PLA. Once proper material formulations and blend preparation are identified, the blends’ 3D printability and structural performance will be assessed by material extrusion additive manufacturing and fracture mechanics-based methods, respectively. A framework will be developed and validated to assess interlayer adhesion and fracture strength in 3D-printed PLA, PLA/PBS, and PLA/PHA, utilizing both experimental methods and finite element analysis. The research will then quantitatively analyze how print parameters, such as nozzle temperature and raster orientation, as well as blend formulation, including composition and compatibilizer, impact the fracture strength of 3D-printed PLA/PBS and PLA/PHA blends using energy- and stress-based fracture mechanics. Finally, the effect of nanomaterials (e.g., graphene) on the printability and fracture performance of PLA-based blend nanocomposites will be investigated, with a focus on how graphene alters the print quality, and the mechanical and thermal properties of these materials.