Polyphosphoric acid is simply a polymer of phosphoric acid. Polyphosphoric acid is not only widely used in medicine, spices, leather, chemical and other industries, but also used for the modification of asphalt.
Polyphosphoric acid is a colorless transparent viscous liquid, which is easy to deliquesce, not crystallized, corrosive, and can be hydrolyzed with water to be orthophosphoric acid, and has a specific gravity of 2.1 g/cm2.
Polyphosphoric acid is a commonly used asphalt chemical modifier. Polyphosphoric acid undergoes two chemical reactions during the modification: neutralization and esterification. The addition of polyphosphoric acid achieves the same effect as polymer modified asphalt with reduced polymer usage. In addition, polyphosphoric acid also improves the resistance of asphalt mixtures to rutting and water damage, and improves the high temperature performance and temperature sensitivity of asphalt.
When polyphosphoric acid is used to modify asphalt, polyphosphoric acid will react with asphalt mainly by neutralization and esterification, resulting in the decrease of acidity of polyphosphoric acid and the formation of insoluble compounds in polar medium of asphaltene. In the above two reactions, polyphosphoric acid reacts with the active sites in the asphalt molecule, which breaks the initially overlapped asphaltene clusters.
Asphalt content is the main factor that directly affects the adhesiveness of asphalt. Adding polyphosphoric acid can increase the content of asphaltene in asphalt by 35%~55%. It can also reduce the aggregation degree of asphaltene and enhance the dispersibility of asphaltene in soft components of asphalt.
105% and 115% of industrial polyphosphoric acid in CD are made from yellow phosphorus produced from our own phosphate ores. The authentic phosphoric acid produced by thermal process industry has less impurities, high content and stable quality. It is mainly used in new asphalt. It is used as dehydrating agent, cyclizing agent and acylating agent in organic synthesis. It is a catalyst or solvent for condensation, cyclization, rearrangement, substitution and other reactions. It is also used as raw material for the production of polyphosphate products in inorganic industry. It is also used as a substitute and analytical reagent for orthophosphate. More details of polyphosphoric acid can be clicked to see.
