Enhancing Debonding of Epoxy-Based Structural Adhesives with Hybrid Dynamic Curing Agents.

Area of Science:

• Materials Science
• Polymer Chemistry
• Adhesive Technology

Background:

• Reprocessable thermosets face a stability-reprocessability trade-off.
• Epoxy resins with β-amino amides offer stability but need high processing temperatures.
• β-amino esters allow lower-temperature processing but have lower creep resistance.

Purpose of the Study:

• To combine the benefits of β-amino amides and β-amino esters in epoxy-based covalent adaptable networks.
• To develop a hybrid dynamic curing agent for improved reprocessability and debonding.
• To create novel debondable structural adhesives with enhanced performance.

Main Methods:

• Designed a poly(β-amino amide-co-β-amino ester) hybrid dynamic curing agent.
• Cured epoxy resins using the hybrid agent.
• Evaluated stress relaxation activation energy.
• Formulated and tested debondable adhesives on various substrates.

Main Results:

• Achieved processable cross-linked materials with a stress relaxation activation energy of 147 kJ/mol.
• Demonstrated effective debonding capabilities.
• Obtained adhesive lap shear strength up to 16 MPa on metal, wood, and composite substrates.

Conclusions:

• The hybrid dynamic curing agent successfully balances stability and reprocessability in epoxy networks.
• The developed adhesives offer high strength and facilitate nondestructive disassembly.
• This approach is particularly beneficial for heat-sensitive materials like wood and composites.