Common plastic polypropylene

Polypropylene (PP) is a thermoplastic (hot-meltable) polymerized from propylene, which is the least dense plastic, usually a translucent colorless solid, odorless and nontoxic.

Because polypropylene has low temperature brittleness, in order to improve this shortcoming, propylene is usually copolymerized with a small amount of ethylene molecules, thus polypropylene is divided into homopolypropylene and copolymerized polypropylene.

Polypropylene has excellent pressure bearing properties, and it is very easy to hot melt welding after being made into pipes. Compared with PE, it can withstand higher temperatures, so it is widely used in home improvement water supply pipes. In the process of using polypropylene as pipeline raw material, it has experienced the following development process:

PP-H is homopolymer polypropylene, commonly known as type I polypropylene. It is completely polymerized from propylene, with poor impact resistance and good high temperature resistance. The prepared pipes are generally used for chemical pipelines or other engineering purposes.

PP-B is a block copolymerized polypropylene, commonly known as type II polypropylene. PP-B has a higher ethylene content, which greatly improves its low temperature impact resistance, but loses its high temperature resistance. Therefore, pipes made of it are generally suitable for cold water systems.

PP-R is a random copolymerized polypropylene, commonly known as type III polypropylene, which is polymerized by a small amount of ethylene monomer and propylene by a trackless copolymerization method. At a certain high temperature, the low temperature impact resistance is improved, and it becomes a more ideal pipeline material that can be widely used in cold and hot water systems. Today, PPR has occupied most of the market for water supply pipes in the field of home improvement, which is inseparable from stability, reliability, ease of installation, and of course, relatively affordable prices.

PP-RCT, also known as high temperature resistant β-crystal PPR, is a modified PPR material, commonly known as type IV polypropylene. Since the hexagonal crystal form is used to replace the monoclinic crystal form of PP-R, in addition to the common physical properties of PP-R, PP-RCT is improved in terms of heat resistance, pressure resistance and toughness. At present, PP-RCT is mostly used in high temperature heating systems.