Comparison of HDPE Geomembrane Production Process-2 Kinds
In the production process of HDPE geomembranes, there are two international production methods, namely the membrane blowing process, and calendering extrusion process. At present, 85% of the existing geomembrane production lines and most of the new geomembrane production lines are film blowing production lines, because the blowing process has the following advantages over the calendering extrusion process:
1) For glossy HDPE geomembrane
The two different production processes have different requirements for geomembrane resin raw materials. The melt index of resin raw material for the calendering extrusion process is generally 0.11 g/10min (test method ASTM D1238 Cond. E), while the melt index of resin raw material for the blown film process is generally 1.0 g/10min (test method ASTM D1238 Cond. E).
This is because the blowing process requires higher requirements for the raw material resin and a higher melt index for the raw material, which results in a geomembrane with better tensile and ductile properties.
On the construction level, HDPE geomembranes with better tensile and ductile properties are better able to withstand external loading loads (landfill waste, heavy machinery, etc.), as shown in the following table:
2) For rough HDPE geomembrane
Blown film process is a one-step forming method, the production of geomembrane rough surface is formed by adding nitrogen blowing, the finished product is a whole, from the samples produced by the Canadian Solmax blown film process can be clearly seen, the brown point of the rough surface is not easy to peel off.
The calendering extrusion process is a two-step forming method, in which the glossy geomembrane is produced first and then the rough surface is formed on the glossy surface by spraying rough particles, the finished product is not a whole material and the rough spots are easy to peel off, which greatly increases the possibility of landslide accidents.
Of course, whether it is blown film or flat extrusion process, the performance of HDPE geomembrane is mainly based on the technical index of geomembrane. For imported geomembranes, the index is the GRI-GM13 international index, in which no distinction or requirement is made between the geomembrane production process and the corresponding resin melt index. Under the same conditions, the majority of projects will use HDPE geomembranes produced by the blown film process, in combination with the above two production processes, for practical construction applications.