An Efficient Polymerization of MHET to PET via a Stepwise Heating Strategy

Area of Science:

• Polymer Chemistry
• Sustainable Materials Science
• Chemical Engineering

Background:

• Polyethylene terephthalate (PET) is a widely used plastic facing production and waste challenges.
• Growing demand necessitates sustainable production and recycling strategies for PET.

Purpose of the Study:

• To develop an efficient and sustainable synthesis of PET.
• To reduce ethylene glycol (EG) consumption in PET production.
• To integrate enzymatic depolymerization with chemical synthesis for PET recycling.

Main Methods:

• Utilized mono(2-hydroxyethyl) terephthalate (MHET), derived from enzymatic PET depolymerization, as a raw material.
• Developed a stepwise heating esterification process with minimized EG usage.
• Optimized reaction conditions for esterification and polycondensation.

Main Results:

• Achieved PET synthesis with a MHET to EG molar ratio of 1:0.2-0.4.
• Shortened esterification to 3-3.5 hours and polycondensation to 1-1.5 hours.
• Synthesized PET exhibited comparable thermal and mechanical properties to commercial PET (e.g., melting point 252.5°C, tensile strength 79.2 MPa).

Conclusions:

• The novel approach significantly reduces EG consumption and total reaction time for PET synthesis.
• This method offers a sustainable pathway for PET production and recycling.
• The synthesized PET demonstrates excellent properties, suitable for commercial applications.