Preparation And Characterization Of UV-curing Magnetic Nanocomposites Based On Waterborne Polyurethane

Waterborne polyurethane have high hardness, good adhesion, corrosion resistance, solvent resistance, and have low VOC amount (volatile organic compounds), in line with the resources, energy and pollution, the prerequisite for development and the ’economy, efficiency, ecology, energy’ principles. However, the disadvantage of the aqueous polyurethane is poor water resistance, poor thermal and mechanical properties. UV-curing is an energy efficient and environmentally friendly curing technology. Accordingly, the combination of water as the solvent and UV curing technology has become an attractive method of preparation polyurethanes. Fe3O4 nanoparticles as inorganic rigid materials can enhance the thermal and mechanical properties of waterborne polyurethane. In addition, nanocomposites can possess magnetic properties desiredly.Therefore, this paper studied waterborne polyurethane having high degree cross linking and UV-curing Fe3O4/waterborne polyurethane nanocomposites. Using Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic thermal analysis, X-ray diffraction, mechanical properties and hardness testing methods to characterize the performance of the nanocomposites. The main results achieved in this study are as follows:1. Trimethylolpropane and isophorone diisocyanate as first synthesis formed hyperbranched prepolymer. based on the prepolymer, we successful synthesized a series of good stability waterborne polyurethane emulsion, and the emulsion can be placed at least 2 years above. By dynamic thermal analysis, the storage modulus of the TWPU have been significantly increased, the glass transition temperature was increased from 90℃ to 125℃. By analysis of the mechanical properties, tensile strength of the TWPU increased from 9.672 MPa to 29.041MPa and the Young’s modulus increased from 39.80 MPa to 225.68 MPa. Besides, the pencil hardness has of TWPU materials greatly improved. By chemical stability analysis, the water resistance, acid and alkali resistance and organic solvents resistance had improvement.2. By solvothermal method Fe3O4 nanoparticles were prepared. Fe3O4 nanoparticles were modified with vinyl triethoxysilane successfully marked as Fe3O4-VTEO. We successfully prepared Fe3O4/TWPU nanocomposite emulsion. By dynamic thermal analysis, when Fe3O4-VTEO content increased, the storage modulus and glass transition temperature of nanocomposites decreased. By analysis of the mechanical properties, when the content of Fe3O4-VTEO increases, the tensile strength, Young’s modulus and elongation at break of the nanocomposites are gradually decreased. By chemical stability analysis, water resistant and organic solvents resistant have some improvement. By magnetic analysis, Fe3O4/TWPU nanocomposites had superparamagnetism.3. By solvothermal method we prepared Fe3O4 nanoparticles and Fe3O4-IPTS were successfully prepared with the nanoparticles modified with isocyanate triethoxysilane (IPTS). We successfully prepared Fe3O4/TWPU-IPTS nanocomposite emulsions, and the emulsion can be placed at least six months above. Fe3O4/TWPU-IPTS nanocomposite emulsions had no settlement of any Fe3O4-IPTS particles. By dynamic thermal analysis, the storage modulus and the glass transition temperature of the material have been raised. By analysis of the mechanical properties, tensile strength, Young’s modulus and pencil hardness of the material increase. By chemical stability analysis, the resistant to water and the organic solvent of nanocomposites have improved. By magnetic analysis, Fe3O4/TWPU-IPTS nanocomposites had superparamagnetism.