Experimental Study on Polysulfide Rubber-Modified Marine Deck Coatings for Enhanced Rolling Load Resistance

Marine deck coatings suffer from premature failures such as wear thinning, flaking, and brittle cracking under repeated rolling, abrupt stopping/steering, and high shear loads of heavy equipment due to the imbalance of hardness, strength, toughness, and wear resistance. To address this issue, a rolling load-resistant coating system with an epoxy–amine/epoxy–thiol dual-crosslinked network was constructed using liquid polysulfide rubber (Lp-3) as the key crosslinking modifier, and the effect of Lp-3 content (0–2 wt%) on the comprehensive performance of the coating was systematically investigated. The results showed that the coating achieved the optimal synergy of properties at 1 wt% Lp-3 loading: Shore hardness reached 88.7 HD with the pencil hardness maintained at 8H, adhesion strength increased to 7.2 MPa, Taber abrasion loss significantly decreased to 14.8 mg, tensile strength rose from 5.5 MPa to 12.4 MPa, elongation at break nearly doubled, shear strength reached 10.2 MPa, and the failure mode transformed from brittle cleavage to ductile shear. Mechanistic analysis revealed that the terminal thiol groups of Lp-3 underwent a click reaction with epoxy groups, covalently embedding flexible polysulfide segments into the rigid epoxy network and forming Fe–S interfacial chemical bonds to enhance adhesion. The microphase separation, chain relaxation, and energy dissipation mechanisms effectively blunted crack propagation and alleviated stress concentration, while maintaining sufficient surface hardness and the continuity of the load-bearing skeleton. This work realizes the synergistic optimization of high strength, high toughness, strong adhesion, and excellent wear resistance for marine deck coatings and provides a new strategy and critical technical parameters for the design of functional coatings under heavy-duty dynamic service environments.