PPR pipes are also called three-type polypropylene pipes and random copolymer polypropylene. The random copolymer polypropylene can be extruded into pipes or injection molded into pipe fittings. Polypropylene random copolymer is also a kind of polypropylene, and the basic structure of its polymer chain is modified by adding different kinds of monomer molecules. Ethylene is the most commonly used monomer, which causes changes in the physical properties of polypropylene. Compared with pp homopolymers, random copolymers have improved optical properties, improved impact resistance, increased flexibility, lowered melting temperature, and thus lowered the thermal welding temperature; at the same time, it has chemical stability and water vapor isolation. Performance and organoleptic properties are basically the same as homopolymers. Used in blow molding, injection molding, film and sheet extrusion processing fields, as food packaging materials, pharmaceutical packaging materials and daily consumer goods.
1. Why does PPR pipe
have low temperature brittleness?
PPR is random copolymer polypropylene, which is what we call type III polypropylene. It is obtained by random copolymerization of propylene monomer and a small amount of ethylene monomer under heating, pressure and catalyst. The ethylene monomer is randomly distributed in the propylene long chain, and the ethylene monomer is generally controlled between 3-5%. The ethylene content and the polymerization method of ethylene and propylene determine its cold brittleness.
In the case of low temperature, especially in the winter construction process, the flexibility of the pipe is reduced at low temperatures, the rigidity is increased, and it is brittle.
Under the impact of external force or excessive accidental load, the pipe may crack in a straight line. Bring inconvenience to construction. For this reason, relevant national regulations have made clear requirements for this issue.