Physical properties and microstructures of organic rectorites and their modified asphalts

Three kinds of organic rectorites (ORECs) were prepared by selecting dodecyl trimethyl ammonium chloride (1231), lauryl dimethyl benzyl ammonium chloride (1227) and stearyl trimethyl ammonium chloride (1831) as organic modifiers to modify Na-REC. Na-REC and ORECs modified asphalts were prepared by using the melting intercalation method. The effect of organic reagents on hydrophilicity of Na-REC was investigated by using hydrophilicity test. The result indicates that 1831-OREC shows the best lipophilicity. Microstructures of Na-REC, ORECs and their modified asphalts were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) tests. Results show that 1831-OREC has the largest interlayer spacing, followed by 1227-OREC. Only 1831-OREC in modified asphalt forms part-exfoliated nanostructure. Effects of ORECs on physical properties, thermal storage stability were studied by penetration, softening point, ductility and viscosity test. It is concluded that introduction of Na-REC and ORECs enhances high temperature property but has the bad effect on low temperature cracking resistance of asphalt. 1831-OREC has the best modification effect on asphalt. Moreover, the 1831-OREC modified asphalt shows the best thermal storage stability. Morphologies of modified asphalts were investigated by atomic force microscope (AFM) test. The result shows that Na-REC and ORECs in asphalt matrix act as nucleators which can contribute to heterogeneous nucleation of asphaltenes.