These Plastics Can Be Used As Water Pipes, But They Are Used For Different Purposes.

- Jan 04, 2020-

These plastics can be used as water pipes, but they are used for different purposes.

As a derivative of petrochemical industry, plastic has become a substitute for many traditional materials with its excellent performance advantages. Today, there are a variety of different types of plastic pipes on the market. They have different colors, some can be bent, and some cannot. Many people may not know what is different between them.

In fact, plastics are also made of various materials, so why are there plastic pipes of different materials? To put it simply, "material determines performance, and performance determines use." So, what plastics are commonly used to make pipes? Maybe you are no stranger to them.

PE polyethylene

Polyethylene (PE) is a thermoplastic polymer polymerized by ethylene (hot-meltable). It is non-toxic, odorless, feels like wax, and has excellent low temperature resistance and chemical stability. The molecular formula is:

— [CH2—CH2] n—

Polyethylene is usually divided into Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE) and High Density Polyethylene (HDPE). Their applications are different. . LDPE is usually used to produce light products such as films and fibers, and when it comes to injection pipe production, HDPE or MDPE is usually used.

When manufacturing pipes, the heat resistance of polyethylene is relatively poor, so in some places with higher requirements (such as heating systems), it needs to be modified, so we have our PE-RT and PE-X.

Polyethylene of Raised Temperature Resistance (PE-RT) refers to heat-resistant polyethylene. It uses a copolymerization method of ethylene and octene to control the number and distribution of side chains to obtain a unique molecular structure to improve the heat resistance of PE.

PE-X (crosslinked-polyethylene) refers to cross-linked polyethylene. Cross-linking makes the linear macromolecular structure of polyethylene into a three-dimensional network structure, thereby improving its heat resistance and creep resistance. Cross-linked polyethylene is not thermoplastic and cannot be heat-fused. Currently commercialized PE-X includes PE-Xa, PE-Xb, and PE-Xc. It is worth noting that a and b here do not mean that the product grade is A or B, but they are undergoing cross-linking The process methods used are different.

PP polypropylene

Polypropylene (PP) is a kind of thermoplastic plastic (hot-melt) polymerized by propylene. It is the plastic with the smallest density, usually a translucent colorless solid, odorless and non-toxic. Its molecular formula is:

— [CH2—CH (CH3)] n—

Due to the low temperature brittleness of polypropylene, in order to improve this disadvantage, propylene is usually copolymerized with a small amount of ethylene molecules, so polypropylene is divided into homopolypropylene and copolymerized polypropylene

Polypropylene has excellent pressure-bearing properties, and it is very easy to be hot-melt welded after being made of pipes. Compared with PE, it can withstand higher temperatures, so it is widely used in home water supply pipes. In the process of polypropylene used as raw materials for pipelines, it has experienced the following development process:

PP-H (Polypropylene-Homopolymer) is homopolymer polypropylene, commonly known as type I polypropylene. It is completely made of propylene, which has poor impact resistance and high temperature resistance. The pipes made are generally used for chemical pipes or other engineering purposes.

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

PP-R (Polypropylene-random copolymer) is a random copolymerized polypropylene, commonly known as type III polypropylene. It is made by polymerizing a small amount of ethylene monomers and propylene in a trackless copolymerization method. It neutralizes PP-H and PP-B. The superior performance can not only withstand a certain high temperature, but also improve the low temperature impact resistance performance, becoming a more ideal, can be widely used in hot and cold water pipe raw materials. Today, PPR has occupied the vast majority of the market for water supply pipes in the home improvement field. This is inseparable from stability, reliability and ease of installation, and of course, relatively affordable prices.

PP-RCT (Polypropylene-Random Crystalline structure temperature resistance) is also called high temperature β-crystalline PPR, which is a modified PPR material, commonly known as type IV polypropylene. Due to the use of hexagonal crystals instead of the monoclinic crystals of PP-R, in addition to the common physical properties of PP-R, PP-RCT has improved heat resistance, pressure resistance, and toughness. At present, PP-RCT is mostly used in high-temperature heating systems.


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