Simultaneous and Gradient IPN of Polyurethane/Vinyl Ester Resin: Morphology and Mechanical Properties

A series of polyurethane (PU) and vinyl ester resin (VER) simultaneous and gradient interpenetrating polymer networks (represented as s‐IPN and g‐IPN, resp.) curing at room temperature were prepared by changing the component ratios of PU or VER in s‐IPN, time intervals, and component ratio sequences of s‐IPN in g‐IPN. The microstructures of s‐IPN and g‐IPN were detected by atomic force microscope (AFM), dynamic mechanical analyzer (DMA), and surface constitution scanning of nitrogen element of energy dispersive X‐ray spectrum (EDX), respectively. The mechanical properties of s‐IPN and g‐IPN were studied by values in strain‐stress curves detected by electronic multipurpose tester. The results indicated that the morphology and mechanical properties are both affected by PU/VER component ratios in s‐IPN, gradient time intervals, and gradient component ratio sequences. Furthermore, the morphology detection by EDX and mechanical properties study both proved the formation of gradient structures in transition regions of g‐IPN.