Preparation of Polyyne and Modify Asphalt
|School||Beijing University of Chemical Technology|
|Course||Chemical Engineering and Technology|
|Keywords||Polyyne Chlorinated parriffin-70 Dechlorination Modified asphalt Softing points Penetration Ductility|
Chlorinated paraffin usually used in flame retardants which because of its fire-retardant properties. Polyyne is obtained by elimination reaction with chlorinated paraffins, which is a linear polymer. Howerer its application is not yet well developed. As we all know, polyyne’s chemical properties are more actived than chlorinated paraffins. Because polyyne contains unsaturated bonds. Obviously, it have a good potential value for the development and utilization of chlorinated paraffin.Modified asphalt can be prepared in many ways, but there is hardly method to comprehensively improve the performance of asphalt. In general,The modifying agentes can imporve the softening point of and reduce the degree of penetration, but it is difficult to maintain the degree of ductility, which is very important for the asphalt in the low temperature. Due to the presence of an unsaturated bond, polyyne can combine with hetero atoms of asphalt and make the asphaltene molecules become bigger because of the side chain becomes longer. Finally the softening point is elevated and penetration is reduced but the ductility is not a sharp decline.In this paper, the main contents are as follows:1.Preparation of polyyneIn an alcohol solution of an alkali, different kinds of polyyne are prepared by dechlorination of chlorinated paraffins under different conditions. The chlorine contents of dechlorination can be measured by two ways:direct ion chromatography and oxygen flask combustion-ion chromatography. The result shows that both methods can accurately determine the amount of dechlorination of chlorinated paraffin, and the results exactly are same. Relatively, the method of directly using ion chromatography is more simple, which provides a basis for the online testing dechlorination of chlorinated paraffins in industry. At the same time, we examine the effect of temperature, times, concentration of alkali for the dechlorination of chlorinated paraffins. As the temperature increases, the time was increased, the alkali concentration increases, also increases in the amount of dechlorination. When the reaction temperature is75℃, the time is17hour, the mass ratio of alkali and chlorinated paraffins is1:1, the amount of dechlorination of chlorinated paraffin is59.9%. We can find that double bond will transfer to triple bond with the dechlorination increase of polyynes by the wijsmethod and infrared spectroscopy analysis.2.To modify bitumen with polyyneAt first, we add the chlorinated polypropylene, chlorinated paraffin, polyyne, ferric chloride and maleic anhydride to asphalt, and the result shows that these substances could increase the softening point of the asphalt and reduce the penetration, but also decreases the ductility of asphalt. On the one hand, chlorinated polypropylene, chlorinated paraffin and ferric chloride as a modifier can reduce the degree of ductility significantly; On the other hand, when polyyne and maleic anhydride modify the asphalt, the degree of decline of ductility is not severe. When the different chlorine content of polyyne add to the asphalt, with increase of chlorine content in the polyyne, softening point is increased, penetration is reduced, and the ductility is gradually decreased. Compared with the chlorinated paraffin, chlorinated polypropylene, and ferric chloride, polyyne change the ductility of asphalt is still relatively small. In fact, when the ductility of the asphalt is too low, its application will be very restricted. Indeed the polyyne with Chlorine content of37.1%has the similar effect on asphalt as maleic anhydride, which can improve the softening point, reduce the degree of penetration,and the ductility is not drastically declined. In other words, it can maintain the low-temperature properties of the asphalt. Compared to the cost of maleic, the polyyne has a distinct advantage.