About the different physical and chemical properties of PVC pipes and PE pipes
Jun. 30, 2021
Chemical and physical properties: PVC pipe is one of the most widely used plastic materials. PVC material is a non-crystalline material.
In actual use, PVC materials often add stabilizers, lubricants, auxiliary processing agents, pigments, impact resistance agents and other additives. PVC material has non-flammability, high strength, weather resistance and excellent geometric stability. PVC has strong resistance to oxidants, reducing agents and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid and is not suitable for contact with aromatic hydrocarbons and chlorinated hydrocarbons. The melting temperature of PVC during processing is a very important process parameter. If this parameter is not appropriate, it will cause the problem of material decomposition. The flow characteristics of PVC are quite poor, and its process range is very narrow. Especially the high molecular weight PVC material is more difficult to process (this kind of material usually needs to add lubricant to improve the flow characteristics), so the PVC material with small molecular weight is usually used. The shrinkage rate of PVC is quite low, generally 0.2~0.6%.
Typical uses: water supply pipes, household pipes, house wall panels, commercial machine housings, electronic product packaging, medical equipment, food packaging, etc. PVC pipe adopts TS interface, and the adhesive used is difficult to guarantee non-toxic. At the same time, the adhesive may contain substances that are beneficial to microorganisms, which will affect the taste and quality of the water. Talking about the discoloration of lead, lead is a big killer to humans, and the lead in PVC water supply pipes indirectly affects people's health seriously. At present, plastic water supply pipes containing lead salts have been banned by countries all over the world. It seems that the banning of lead-containing PVC pipes is the general trend.
PE polyethylene water supply pipe:
①Good temperature resistance performance, low temperature embrittlement temperature, can be used in the range of -75℃~40℃, pipeline embrittlement will not occur during winter installation and construction. Corrosion resistance: polyethylene is an inert material and can withstand a variety of chemical media Corrosion, no need for corrosion protection. There will be no rot, rust and corrosion.
②Good flexibility: The elongation at break exceeds 800%, local vibration will not cause all the pipes to vibrate, and the vibration resistance is strong.
③ Strong pressure resistance: Due to the high crystallinity of HDPE, the strength and hardness increase accordingly. The welding is tight, can withstand internal pressure, and is generally used in water supply and gas pressure pipelines.
④ Sanitary and non-toxic, no bacteria grow in the pipe, no secondary pollution of water quality, and completely solved the defect of pipeline pollution to the water source.
⑤Good flow capacity: smooth inner wall, low friction coefficient, low fluid resistance, low head loss, no scaling, reducing pipeline pressure loss and water delivery energy consumption, economic advantages are obvious.
⑥Long service life: PE black pipe contains about 2.5% carbon black. It has strong resistance to ultraviolet radiation and can be stored or used outdoors. The service life is up to 50 years.
In actual use, PVC materials often add stabilizers, lubricants, auxiliary processing agents, pigments, impact resistance agents and other additives. PVC material has non-flammability, high strength, weather resistance and excellent geometric stability. PVC has strong resistance to oxidants, reducing agents and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid and is not suitable for contact with aromatic hydrocarbons and chlorinated hydrocarbons. The melting temperature of PVC during processing is a very important process parameter. If this parameter is not appropriate, it will cause the problem of material decomposition. The flow characteristics of PVC are quite poor, and its process range is very narrow. Especially the high molecular weight PVC material is more difficult to process (this kind of material usually needs to add lubricant to improve the flow characteristics), so the PVC material with small molecular weight is usually used. The shrinkage rate of PVC is quite low, generally 0.2~0.6%.
Typical uses: water supply pipes, household pipes, house wall panels, commercial machine housings, electronic product packaging, medical equipment, food packaging, etc. PVC pipe adopts TS interface, and the adhesive used is difficult to guarantee non-toxic. At the same time, the adhesive may contain substances that are beneficial to microorganisms, which will affect the taste and quality of the water. Talking about the discoloration of lead, lead is a big killer to humans, and the lead in PVC water supply pipes indirectly affects people's health seriously. At present, plastic water supply pipes containing lead salts have been banned by countries all over the world. It seems that the banning of lead-containing PVC pipes is the general trend.
PE polyethylene water supply pipe:
①Good temperature resistance performance, low temperature embrittlement temperature, can be used in the range of -75℃~40℃, pipeline embrittlement will not occur during winter installation and construction. Corrosion resistance: polyethylene is an inert material and can withstand a variety of chemical media Corrosion, no need for corrosion protection. There will be no rot, rust and corrosion.
②Good flexibility: The elongation at break exceeds 800%, local vibration will not cause all the pipes to vibrate, and the vibration resistance is strong.
③ Strong pressure resistance: Due to the high crystallinity of HDPE, the strength and hardness increase accordingly. The welding is tight, can withstand internal pressure, and is generally used in water supply and gas pressure pipelines.
④ Sanitary and non-toxic, no bacteria grow in the pipe, no secondary pollution of water quality, and completely solved the defect of pipeline pollution to the water source.
⑤Good flow capacity: smooth inner wall, low friction coefficient, low fluid resistance, low head loss, no scaling, reducing pipeline pressure loss and water delivery energy consumption, economic advantages are obvious.
⑥Long service life: PE black pipe contains about 2.5% carbon black. It has strong resistance to ultraviolet radiation and can be stored or used outdoors. The service life is up to 50 years.