Waterborne polyurethane (WPU) is a waterborne coating with excellent physicochemical properties. Its deficiencies of water resistance, chemical resistance, staining, and hardness have limited the wide application of polyurethane in the wood lacquer market. In this study, polycarbonate diols (PCDL) were used as soft segments and WPCU was modified by cross-linking using Trimethylolpropane (TMP) to prepare polycarbonate type WPU (WPCU) with cross-linked network structure. The new wood lacquer was prepared by adding various additives and tested by applying it on wood board. The successful synthesis of WPCU was determined by FTIR testing, and the cross-linking degree of WPCU was probed by low-field NMR. The viscosity of the cross-linked WPCU emulsion showed a decreasing trend compared to the uncross-linked WPCU emulsion, and WPCU-2 had the smallest particle size. Compared with the uncrosslinked WPCU film, the crosslinked WPCU film had lower water absorption (2.2%), higher water contact angle (72.7°), excellent tensile strength (44.02 MPa), higher thermomechanical, and better water and alcohol resistance. The effect of crosslinker content on the microphase separation of WPCU chain segments on the surface roughness of the film was investigated by SEM. The wood paint prepared by WPCU emulsion has good dry heat resistance, chemical resistance, and adhesion, and the hardness of the wood paint when the TMP content is 3% reaches H. It also has good resistance to sticky stains, which can be used to develop new wood lacquer.

The shape memory polyurethane (SMPU) fabrics were knitted with different SMPU fiber contents for the investigation of its bagging behaviour in this paper. The bagging deformation and recovery of these SMPU-knitted fabrics were determined at different temperatures to evaluate its temperature sensitivity. Our experimental results show that the bagging behavior of the SMPU-knitted fabrics is highly correlated with the amount of SMPU fibers knitted inside the SMPU fabrics. The switching temperature of the SMPU-knitted fabrics is found to be above the phase transfer temperature of SMPU. A comparison between Lycra and SMPU-knitted fabrics is also conducted to validate the shape memory bagging behavior of SMPU-knitted fabrics.