Recycling Waste Polyester via Modification with a Renewable Fatty Acid for Enhanced Processability

Area of Science:

• Polymer Science
• Materials Science
• Sustainable Chemistry

Background:

• Recycled polyethylene terephthalate (PET) processing is hindered by thermally unstable contaminants and additives.
• Lower processing temperatures are crucial for efficient and safe recycling of PET waste.

Purpose of the Study:

• To investigate the use of renewably sourced tall oil fatty acid (TOFA) as a modifier for recycled PET.
• To assess the impact of TOFA on PET's thermal, mechanical, and morphological properties for improved processing and fiber formation.

Main Methods:

• Polyethylene terephthalate (PET) was compounded with varying concentrations of tall oil fatty acid (TOFA).
• Samples were extruded at 240 °C, and their phase transition behaviors were analyzed using thermal and dynamic mechanical analyses.
• Melt viscosity was measured at elevated temperatures (240 and 250 °C).
• Melt-spun filaments were produced and characterized for tensile strength, modulus, and elongation.

Main Results:

• TOFA addition shifted PET's melting and recrystallization temperatures to lower values.
• The glass transition temperature of PET decreased significantly from 91 °C to 65 °C.
• TOFA induced crystal-phase imperfections, slowing recrystallization and stabilizing melt viscosity.
• Melt-spun PET fibers exhibited good mechanical properties: 29-38 MPa tensile strength, 2.7-2.8 GPa tensile modulus, and 20-36% elongation.

Conclusions:

• Renewably sourced TOFA effectively plasticizes recycled PET, enabling lower processing temperatures.
• Modified PET demonstrates potential for producing high-performance polymeric fibers from waste materials.
• This approach offers a sustainable pathway for upcycling PET waste into valuable products.