Bio-based unsaturated polyester resin from post-consumer PET

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Poly(ethylene terephthalate) (PET) waste presents a significant environmental challenge.
• Traditional unsaturated polyester (UP) resins often rely on styrene, posing health and safety risks.
• There is a growing demand for sustainable alternatives in composite materials.

Purpose of the Study:

• To synthesize styrene-free unsaturated polyester (UP) resins utilizing post-consumer poly(ethylene terephthalate) (PET) waste.
• To investigate the copolymerization capabilities of the synthesized UP resin with non-styrene reactive diluents.
• To evaluate the mechanical properties and thermal characteristics of the resulting cured materials.

Main Methods:

• Glycolysis of PET waste with diethylene glycol followed by condensation polymerization with bio-based itaconic acid.
• Formulation of resins using methacrylates and itaconates as reactive diluents.
• Room temperature redox initiation curing followed by elevated temperature post-curing.
• Characterization using Dynamic Mechanical Analysis (DMA) and standardized mechanical testing (tension, flexure, compression).

Main Results:

• Successful synthesis of UP resin from PET waste with reactive methylidene functions.
• Demonstrated copolymerization with non-styrene diluents like dimethyl itaconate (DMI).
• Achieved high ultimate flexural strength (161.4 MPa) and compressive yield point (131.3 MPa) with DMI-containing formulations.
• Low volatility of DMI addresses styrene-related health, safety, and ecological concerns.

Conclusions:

• Upcycling PET waste into high-performance, styrene-free UP resins is feasible.
• Bio-based itaconate diluents enable the formulation of sustainable and robust composite materials.
• This approach offers a promising solution for environmentally friendly composites and PET waste management.