Pulished on Aug. 04, 2020
As a Water Supply Pipeline Manufacturer, share with you. During the whole
process of construction, some PE pipes will be found to be non-smooth and
dented. What are the reasons for the non-smooth surface of PE pipes?
HDPE Pipe
1. First, remove the surface roughness caused by water. Only applicable to new PE materials.
2. The surface roughness of the PE pipe surface is only produced in a too thin layer, which is also a kind of melt cracking, but it is different from the general melt fracture, which is the unstable fluidity of all melts. . The surface roughness only occurs in a too thin layer on the pipe surface. The pipe surface roughness is generated in a part of the mold. When the surface of the polyethylene water supply pipe is smooth, the molecular structure of the melt surface must be relaxed to a certain level before the entrance and exit of the mold.
3. Physical expression of surface roughness of PE pipe:
Surface roughness is caused by the friction between the melt and the mold surface, and has nothing to do with the mold surface roughness. This kind of friction is caused by the adhesion between the melt and the surface of the mold metal material.
PE pipe surface must be polished with lubricating fluid. High-viscosity and high-density high-pressure polyethylene (HDPE) can produce lubricating fluid on the surface of the extrusion die. Because the molecular structure chain entanglement point of high-viscosity high-pressure polyethylene is relatively small, with the development of the entire extrusion process, a part of the molecular structure chain can be separated from the melt under the effect of the mold surface and "hang" on the mold. Lubricant is produced on the surface. This type of lubrication is a stable balance. For low-viscosity and high-pressure polyethylene, because of the strong entanglement between the molecular structure chains, the molecular structure chains are not easy to extract from the melt, so they cannot be reasonably wetted, and the pipe surface will be very uneven.
The surface of low viscosity high pressure polyethylene is not smooth. A molecular structure is obtained from the surface of the melt as a research object. One end of the molecular structure adheres to the surface of the mold, and the other end is entangled with other molecular structures, so there is a force on both sides of the molecular structure. Because of the entanglement force of low-viscosity and high-pressure polyethylene, the adhesion between the molecular structure and the mold surface is dragged, and the molecular structure is "straight." Once the melt leaves the mold shell, the adhesion force between the melt and the mold shell surface will subside, and the entanglement force between the molecular structure and the surrounding molecular structure will still exist. Because the molecular structure is already in tension before the inlet and outlet molds, the inlet and outlet molds cannot be bent immediately. Only after the inlet and outlet molds are bent, the result of the bending of the inlet and outlet molds is to produce dents on the pipe surface. The preparation of low-viscosity high-pressure polyethylene is smooth and clean, with only additional lubricating fluid. The stronger way today is to increase the lubricant.
Our company also has HDPE Pipe on sale, welcome to contact us.
