Abstract
To enhance the rain erosion resistance of wind turbine blade leading-edge protection materials, a series of modified polyurethane (PU) composites were developed by optimizing the synthesis process of PU prepolymers – specifically by tuning the isocyanate (NCO) content, selecting polycaprolactone diols (PCL) with different molecular weights, and introducing an organic titanium catalyst (2210) and hydroxy-terminated polydimethylsiloxane (HO-PDMS). The effects of these components on the mechanical properties, rain erosion resistance, and thermal stability were systematically investigated. Results showed that optimizing the NCO content balanced strength and toughness, achieving a tensile strength of 25.0 MPa at 6% NCO and peak hardness (94.2 Shore A) at 9% NCO. Higher molecular weight PCL (2,000 g/mol) significantly enhanced tensile strength (27.72 MPa) and elongation at break (395.2%) due to improved microphase separation. The addition of 0.03 wt% catalyst 2210 reduced demolding time to 49 min and improved mechanical properties. PU containing 7 wt% HO-PDMS (Mn = 1,000 g/mol, sample SPU7) exhibited optimal rain erosion life (31.6 h), superior thermal stability, and high storage modulus. However, excessive HO-PDMS (e.g., SPU9) led to interfacial defects. This study provides a promising strategy for developing long-lasting, high-reliability protective materials for wind turbine blades.