High residue bio-based structural-functional integration epoxy and intrinsic flame retardant mechanism study

Area of Science:

• Polymer Science and Materials Science
• Focus on structural-functional integration of polymers
• Development of advanced composite matrices and structural materials

Background:

• Intrinsic flame-retardant epoxy resins with high mechanical properties and reusability are crucial for modern materials.
• Existing epoxy materials often lack sufficient flame retardancy or recyclability.
• Bio-based polymers are gaining importance for sustainable material development.

Purpose of the Study:

• To synthesize novel bio-based epoxy resins with inherent flame-retardant properties.
• To evaluate the mechanical performance, thermal stability, and reusability of the synthesized epoxies.
• To elucidate the flame-retardant mechanism, particularly the role of nitrogen-phosphorus synergy.

Main Methods:

• Synthesis of two novel bio-based epoxy resins, VSE and VDE.
• Curing with 4,4-diaminodiphenyl methane (DDM) and mechanical property testing (Young's modulus).
• Flame retardancy assessment (Limiting Oxygen Index - LOI, UL-94 rating, char residue analysis) and recyclability testing.
• Advanced characterization including TGA-IR and EDS coupled with SEM to investigate flame-retardant mechanisms.

Main Results:

• Synthesized VSE and VDE achieved high Young's moduli (5013 MPa and 4869 MPa, respectively).
• Both resins demonstrated excellent flame retardancy, meeting UL-94 V-0 rating with high LOI values (38.7% and 34.5%) and char residue.
• Cured VDE showed remarkable reusability, maintaining structural integrity after reshaping upon heating and cooling.

Conclusions:

• The newly developed bio-based epoxy resins possess superior flame retardancy, mechanical properties, and recyclability.
• The study reveals the intrinsic flame-retardant mechanism involving nitrogen-phosphorus synergy.
• These epoxies present significant potential for applications in coatings, potting, and composite matrices.