Research On The Microstructure And Ultraviolet Aging Of Asphalt/Organo-montmorillonite Composites

Compared with conventional polymer matrix composites, polymer/layered silicate nano-composite materials, being due to their special structure and excellent performance, which leads to widespread attention of researchers. The polymer/ layered silicate nanocomposites research and development of composite technology and ideas used in asphalt modification, are expected to develop high strength, high toughness, high temperature aging, a new road with water-resistant modified bitumen materials.In this paper, the montmorillonite was modified with two kinds of alkyl quaternary ammonium salt (cetyl trimethy ammonium bromide, octadecyl dimethyl benzyl ammonium chloride) to get two kinds of organic montmorillonite (OMMT1 and OMMT2), a series of asphalt/montmorillonite composites are prepared via melt interclation, and are carried out UV aging test.The effect of montmorillonite on the four components distribution, physical properties before and after UV aging were investigated. The microstructures of composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FTIR) and UV-Vis diffuse reflectance spectroscopy. The composite structure is simulated by two modules of Reflex and Discover in Materials studio software. FTIR quantitative analysis was used to study anti-aging ability of composite, and established the model of modified mechanism.The main results obtained are as follows:(1) The montmorillonite was modified with two kinds of alkyl quaternary ammonium salt(cetyl trimethy ammonium bromide, octadecyl dimethyl benzyl ammonium chloride) to get two kinds of organic montmorillonite(OMMT 1,OMMT2), XRD, FTIR and UV-vis suggest that organic functional groups have been successfully intercalated into the layers of montmorillonite, the layer spacing increase in varying degrees, ordered by OMMT2>OMMT1>MMT, organic funct-ional groups can interact with PP strongly, the absorption band of MMT appeared blue shift in varying degrees and the absorption intensity decreased, UV reflectance was significantly increased, the reflectivity order by OMMT2>OMMT1>MMT. (2) A series of asphalt/montmorillonite composites were prepared via melt intercalation, the effect of different kinds of and different contents of montmorillonite on the structure of composites was studied. XRD, FTIR and UV-vis suggest that the formation of SK70/MMT composite is an immiscible system, SK70/OMMT1 and SK70/OMMT2 are to form intercalation system, and interlayer distance further increase compared to the two organic montmorillonite, the FTIR spectra change before and after the melt intercalation between SK70 with OMMT1 and OMMT2, the absorption peak of the 1000-1100cm-1 range split, indicating there was not just the physical mixing, also produced the interaction between them, the UV absorption of the series of composite in the 200-800nm UV range reduced in different degrees, and the decline in the 300-700nm is more obvious.(3) Physical properties test result show that the addition of montmorillonite into asphalt increases the softening point and viscosity, improved compatibility with asphalt. UV aging test suggest that the viscosity aging index and the increment in softening point decrease with the increase of montmorillonite dosage, indicating that MMT can reduce the degree of aging of asphalt, improveed the anti-aging capacity.The changes of structure after UV aging studied by FTIR technique and quantitative analysis anti-aging ability of composite. The results suggest that carbonyl peak area increased after UV aging, and increased carbonyl trends:SK70> SK70/MMT>SK70/OMMT1>SK70/OMMT2,long-term UV aging studies show that, the inhibition of carbonyl produce is more significantly in the UV aging early after the addition of OMMT2, while long-term anti-aging capacity is not significant, quality change after UV aging show the quality coefficient of SK70/OMMT2 composite is less than SK70 matrix asphalt.(4) The formation process of composite is simulated by Discover module in Materials studio software, and used Reflex module simulate the X-ray diffraction spectra, theoretical simulation results suggest that the structure of montmorillonite and asphalt conformation are changed, theoretical simulation results well explain the experimental results.