Effect of 3-Aminopropyltriethoxysilane on Solvent Resistance, Thermal Stability, and Mechanical Properties of Two-Component Waterborne Polyurethane

A two-component waterborne polyurethane (2K-WPU) was obtained by the reaction between a hydroxyl-component waterborne polyurethane and a hydrophilically modified polyisocyanate. A hydroxyl-component waterborne polyurethane with a cross-link structure of Si-O-Si groups was synthesized by means of 3-aminopropyltriethoxysilane (APTES) and trimethylolpropane end-capping concurrently. Mean particle size and viscosity of the hydroxyl-component WPU mini-emulsions were examined by a laser particle analyzer and a Brookfield viscometer. Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were utilized to analyze the chemical structure of 2K-WPU films. The influence of APTES content on thermal stability, mechanical properties, and solvent resistance of 2K-WPU films was also investigated by thermogravimetric analysis (TGA), a universal testing machine, and an immersion test under three kinds of solvent (ethanol, acetone, and dichloromethane) for 24h, respectively. The results show that 2K-WPU films containing APTES have excellent thermal stability, tensile strength, and breaking elongation. Additionally, these films possess the strongest resistance to ethanol, as well as resistance to acetone and dichloromethane to a certain extent at the APTES content of 4wt.%.