Research Of Polyurethane Filling Material Under The High-speed Railway Slab Track

“Four vertical and four horizontals” high-speed railway and six major intercity travel systems have been implemented with the development of high-speed railway in China. In 2012 and 2013, high-speed railways have been formed the network effect. Thus, it will have great influence to the existing transportation system. The construction and put into operation of high-speed railway passenger dedicated line is conducive to relieve the tense situation of railway transportation.Now, Ballastless slab track is the main stream of slab structure for high-speed railway. Scientists and engineers were interested in resin filling materials because the complex of operation process and low strength of the traditional material CA(cement asphalt). The application of polyurethane fillers in the slab track can not enhance the performance, but also reduce the cost in a certain extent. It was very important that new polyurethane fillers were researched for developing of high speed railway in our country.In this paper, the development of polyurethane resin and the research of polymer composite material filled with inorganic particles were introduced. The surface modification technology of inorganic fillers was also discussed and KH560(γ-(2,3-epoxy propoxy)propy trimethoxy silane) were used as organically modified agents in the modification of several kinds of fillers including fly ash, silicon dioxide, and calcium carbonate and so on. Composites of PUR(polyurethane rubber)/fly ash, PUR/silicon dioxide, PUR/calcium carbonate and PUR/montmorillonite were prepared. The modified and unmodified inorganic particles and composite material were investigated by FTIR(fourier transform infrared spectroscopy), SEM(scanning electron microscope), XRD(X-ray diffraction), which indicated a strong interaction between the inorganic particles and the organically modified agent. The modified materials were studied by TEM(Transmission electron microscope), XRD that reveal the relationship between structure and properties of materials. The paper provided a new method for polyurethane modification.The composites and elastomers were made through component A and B. Component A, which was the pre-polymer of PU(polyurethane), was synthesized by MDI-50 and polyether polyols. Component B was curing agent and modified stuffing. The influences of the inorganic materials on the mechanical properties, thermodynamic performance of PU were studied with SEM, TEM, TGA(thermo gravimetric analyzer), XRD and mechnical experiments. The results were shown as following.(1)When the PU material was synthesised, R value(the stoichiometric ratio of isocyanate to active hydrogen containing compounds) had significant impact on the mechanical properties of materials. With the increasing of the R value, the compression strength of the PU materials increased, whereas the elastic modulus of the PU material increased, the optimum value of the R was 3.0 and then decreased. In addition, with the increasing content of trihydric alcohol, the compression strength and elastic modulus decreased and then gradually increased. The content of trihydric alcohol was 60 %, the compression strength and elastic modulus of the material reached the maximum.(2)Curing agent constituted the hard segment of PUR, curing agent has the great impact on the mechanical properties of materials. The curing agent of B component was DMTDA(Dimethyl Thio-Toluene Diamine). With the increasing of the DMTDA, the compression strength and elastic modulus of materials increased. When DMTDA was 70 %, compression strength and elastic modulus reached the maxmium and then decreased.(3)The surface modification of fly ash, silicon dioxide, calcium carbonate, montmorillonite used silane couping agent KH560 as the modifier and anhydrous ethanol as the solvent. XRD、FTIR、TGA and TEM indicated that modified inorganic particles with KH560 and polyurethane matrix had bonding effects, and the modified powder particles could be dispered uniformly in polyurethane elastomer. The results showed that the modification of inorganic particles using KH560 was successfully.(4)The PUR/modified fly ash, PUR/modified silicon dioxide, PUR/modified montmorillonite and PUR/modified calcium carbonate composites were prepared. The SEM showed that the surface was smooth, orderly, the inorganic particles dispersed homogeneously in the polyurethane matrix, and modifying inorganic particles had good compatibility with the matrix. From the view of mechanics, the mechanical properties of polyurethane/modified inorganic fillers composites such as compression strength, elastic modulus were superior to polyurethane/unmodified inorganic fillers composites, pure polyurethane elastomers, which could meet the basic application requirement of industrial production.