Eco-Friendly Epoxy-Terminated Polyurethane-Modified Epoxy Resin with Efficient Enhancement in Toughness

Area of Science:

• Materials Science
• Polymer Chemistry
• Composite Materials

Background:

• Polyurethane is a common toughening agent for epoxy resins.
• Existing methods using isocyanate-terminated polyurethane (ITPU) have drawbacks, including harsh storage, limited compatibility, and solvent use.
• These limitations hinder the broader application of toughened epoxy resins.

Purpose of the Study:

• To develop a facile and green approach for preparing toughened epoxy resins.
• To investigate the effectiveness of epoxy-terminated polyurethane (EPU) as a toughening agent.
• To compare the performance of EPU with traditional ITPU.

Main Methods:

• A novel, solvent-free method was employed to synthesize EPU-modified epoxy resins.
• Varying concentrations of EPU were incorporated into the epoxy resin matrix.
• Mechanical properties (toughness, elongation at break) and thermal properties (glass transition temperature, thermal stability) were evaluated.

Main Results:

• The addition of EPU significantly enhanced the toughness and elongation at break of epoxy resins.
• A 30 wt% EPU content resulted in a 358.36% increase in elongation at break and a 73.56% increase in toughness.
• EPU demonstrated superior toughening performance compared to ITPU, with minimal impact on glass transition temperature and thermal stability.

Conclusions:

• Epoxy-terminated polyurethane offers a promising, green alternative for toughening epoxy resins.
• The developed method overcomes the limitations associated with ITPU.
• EPU modification provides a significant improvement in mechanical properties without substantial compromise to thermal performance.