What are the characteristics of pp*** polymer?

Homopolypropylene means that there is only one kind of link in the main chain of polypropylene, and polypropylene is distributed with links formed by the reaction of other monomers except propylene links. * * * Polypropylene can change the properties of polypropylene to a great extent. Polypropylene of propylene and ethylene can be divided into block * * * poly and random * * * poly, whose English abbreviations are PP-B and PP-R respectively. PP-B is obtained by removing unreacted propylene after polymerization of single propylene and then polymerizing with ethylene. In fact, it is a mixture of polypropylene, polyethylene and end-block polymer. It not only maintains a certain rigidity, but also improves the impact resistance of polypropylene, especially the impact resistance at low temperature, but the transparency and gloss are obviously reduced. The purpose of PP-R is to mix propylene and ethylene monomers together for polymerization, and the segments after the reaction of propylene monomer or ethylene monomer are randomly distributed on the polymer backbone. The existence of ethylene segments makes the * * * polymer unable to crystallize. Even if the ethylene content is small, the crystallization ability of polypropylene will be greatly reduced. For example, when the ethylene content is 3%, the glass transition temperature of polypropylene decreases 1 1℃. If this kind of polypropylene is used as raw material to make films, its minimum use temperature can be reduced by about 65438 00℃. PP-R is characterized by low crystallinity and good transparency. Compared with polypropylene homopolymer (PP-H), at the same melt flow rate, the brittleness temperature of PP-R is significantly reduced, and the impact strength is also improved. In recent years, the application of random polypropylene PP-R in hot water supply pipeline has been recognized and widely used. PP-R pipes can transport hot water at 70℃, and the service life can reach 50 years when the long-term internal pressure reaches 1MPa. At the same time, because the thermal conductivity of this material is only 200% of that of alloy steel pipe, it has excellent thermal insulation performance when transporting hot water, and can save energy significantly when used in hot water and heating systems. Famous PP-R pipe manufacturers include BOREALIS, HOECHST and PCD.