Silane assisted EPDM modification of epoxy adhesives for enhanced performance in Al 7075-T6 joints

This study presents a silane-assisted Ethylene Propylene Diene Monomer EPDM-modified epoxy adhesive for bonding Al 7075-T6, balancing mechanical performance with environmental sustainability. Quantitative results show that the 5 wt% EPDM modification increased lap shear strength to 5.79 MPa, a 29% improvement over neat LY 564 (4.49 MPa). Furthermore, the modified system exhibited a peak impact force of 1463 N, representing a 65% increase compared to the 885 N of the unmodified epoxy. While the EPDM incorporation increased the contact angle by 8°, reducing physical wetting, silane-mediated chemical interactions compensated for this, yielding superior joint strength and enhanced hydrophobicity. Thermomechanical analysis confirmed that the modified adhesive achieved a higher storage modulus and thermal resistance than the commercial Aremco 2310 reference. Environmentally, a cradle-to-gate life cycle assessment (LCA) using the ReCiPe 2016 method revealed that the LY 564–EPDM formulation outperformed the reference in 19 out of 22 midpoint categories. Notably, the integration of recycled EPDM rubber drove 80–100% reductions in key categories like Global Warming Potential and human toxicity. These findings demonstrate that silane-assisted EPDM modification enables a quantified enhancement of joint integrity and impact resistance while significantly lowering the production-phase environmental burden for aerospace structural bonding.