Thesis Defence: Mechanical Recycling of Polyethylene Terephthalate Glycol-Modified: Incorporation of Carbon Nanotubes Towards Functional Composites
November 22 at 10:00 am - 2:00 pm
Nadia Abdollahi Goraghani, supervised by Dr. Abbas Milani and Dr. Mohammad Arjmand, will defend their thesis titled “Mechanical Recycling of Polyethylene Terephthalate Glycol-Modified: Incorporation of Carbon Nanotubes Towards Functional Composites” in partial fulfillment of the requirements for the degree of Master of Applied Science in Mechanical Engineering.
An abstract for Nadia Abdollahi Goraghani’s thesis is included below.
Defences are open to all members of the campus community as well as the general public. Registration is not required for in-person defences.
ABSTRACT
Polyethylene terephthalate glycol-modified (PET-G) is widely used in packaging, medical products, and 3D printing due to its enhanced flexibility, clarity, and chemical resistance. However, its modified chemical structure makes PET-G incompatible with standard PET recycling processes, leading to significant environmental challenges as PET-G waste often ends up in landfills or incinerated. This study explores the mechanical recycling of PET-G by incorporating carbon nanotubes (CNTs) to develop high-performance nanocomposites suitable for electromagnetic interference (EMI) shielding applications.
Three grades of PET-G—two recycled and one virgin—were processed using twin-screw extrusion to integrate CNTs at five different weight concentrations (1–5 wt%). Compression moulding was then employed to prepare test specimens for comprehensive mechanical, electrical, thermal, and morphological characterization. The incorporation of CNTs enhanced the mechanical properties of the recycled PET-G nanocomposites, with a notable increase in elastic modulus and improvement in tensile strength compared to the base recycled PET-G. Electrical conductivity measurements revealed a percolation threshold at around 3 wt% CNTs, beyond which conductivity increased markedly due to the formation of conductive networks—an essential feature for effective EMI shielding. The nanocomposites exhibited substantial EMI shielding effectiveness at CNT concentrations above 4 wt%, indicating their suitability for applications in electronics, automotive components, and aerospace devices. To balance material performance and processing efficiency, a multi-criteria decision-making (MCDM) framework, specifically the PROMETHEE II method, was utilized. This approach guided the selection of the optimal CNT loading and base polymer for specific applications by evaluating multiple criteria simultaneously. In conclusion, this research demonstrates that upcycling PET-G waste into CNT-reinforced nanocomposites presents a viable and sustainable pathway for reducing plastic waste while creating high-value materials for advanced technological applications. By transforming waste into functional materials suitable for EMI shielding, the study contributes to circular economy practices and reduces reliance on virgin plastics, promoting environmental sustainability and resource efficiency.
