Abstract
A novel Clay / Waterborne Polyurethane (WPU) nanocomposite has been synthesized by polyurethane and organoclay. Clay was organically modified with swelling agent, 1,12-Diaminododecane. The characterization and hydrogen bonding of the nanocomposite were conducted by Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). d-spacing of clay was determined by X-ray diffraction(XRD) and confirmed by transmission electronic microscopy (TEM).XRD and TEM analysis showed that clay still remains its layer structure in the Clay / Waterborne Polyurethane (WPU) nanocomposite, i.e., this nanomaterial is intercalated nanocomposite and its d-spacing is about 4 to 5 nm. FT-IR showd that addition of clay will not affect the structure of waterborne polyurethane and hydrogen bonding increased drastically by adding organo-clay.GPC results indicate that molecular weight decreased as clay content increasing. Thermal properties of the nanocomposites were examined by thermogravimetric analyzer (TGA) and Differential Scanning Calorimeter (DSC). Results showed that adding clay would raise the temperature of thermal degradation by 15℃(from 247.8 ℃ increased to 261.9℃) and increase the glassy transition temperature more than 50℃(from –16.1℃ increased to 34℃).Mechanical and wear properties of clay were determined by Instron testing machine and confirmed by wearing machine. Mechanical and wear property revealed that introducing clay into WPU polymer can enhance Young’s modulus(from 55.67 MPa increased to 126.14 MPa)、Maximum stress(from 3.97 MPa to 7.61 MPa) and elongation at break(from 27.7% to 58.7%) about two times and wear loss is only one third of neat WPU.Optical property and particle size were examined by UV-visible analyzer and Zeta-Potential / particle sizer. Surface morphology was analyzed by Atomic Force Microscopy (AFM). The optical property displayed that clay can effectively ease yellowing of WPU. The particle size of the nanocomposite increased with the increasing of soft segment molecular weight and clay contents. AFM microphotograph showed that the surface of clay / waterborne polyurethane nanocomposite was smother when adding clay in WPU; Average roughness (Ra) decreased from 0.999 to 0.197 .