Structure and Properties of Reactively Extruded Opaque Post-Consumer Recycled PET

Area of Science:

• Polymer Science
• Materials Science
• Chemical Engineering

Background:

• Opaque PET, often containing TiO2 nanoparticles, presents unique recycling challenges compared to transparent PET.
• Limited research exists on the effective recycling of opaque PET, hindering its sustainable management.

Purpose of the Study:

• To investigate the reactive extrusion of post-consumer opaque PET using Joncryl as a chain extender.
• To analyze the impact of reactive extrusion on the molecular, thermal, mechanical, and rheological properties of recycled opaque PET (r-PET).

Main Methods:

• Reactive extrusion of post-consumer opaque PET with 1% w/w Joncryl.
• Analysis of molecular weight, crystallization rate, and chain structure.
• Rheological investigations using Small Amplitude Oscillatory Shear (SAOS), Large Amplitude Oscillatory Shear (LAOS), and elongational studies.
• Evaluation of mechanical properties, including elongation at break.

Main Results:

• Joncryl addition moderately increased molecular weight and induced long-chain branching, creating a material with enhanced elastic behavior.
• A decrease in crystallization rate was observed, attributed to branching interrupting crystallizable sequences.
• Mechanical properties improved with enhanced rheological characteristics, comparable to virgin PET, without significant loss in elongation at break.

Conclusions:

• Reactive extrusion is an effective method for recycling opaque PET, yielding a material with improved properties.
• The process successfully introduces chain extension and long-chain branching, enhancing rheological performance.
• Recycled opaque PET (REX-r-PET) demonstrates mechanical properties competitive with virgin PET, promoting circular economy principles.