Comparison between blown film process & flat extrusion process

In terms of the production process of HDPE geomembrane, there are currently 2 production methods domestically and internationally, namely the blown film process and the flat extrusion process. At present, 85% of the existing geomembrane production lines are blown film production lines. This is because the blown film process has the following advantages compared with the flat extrusion process:


1) For smooth HDPE geomembrane products:

The two different production processes have different requirements for the raw materials of geomembrane resin. The melt index of the resin raw material for the flat extrusion process is generally 0.11 g/10min (test method ASTM D1238 Cond.E), and the melt index of the resin raw material for the blown film process is generally 1.0 g. /10min (Test method ASTM D1238 Cond.E).

This is because the film blowing process has higher requirements for PE resins and higher requirements for the melt index of the raw materials. The geomembrane products produced in this way have better tensile and elongation properties. From the perspective of actual construction on site, The HDPE geomembrane with better tensile ductility can better withstand external loading loads (landfill, heavy machinery, etc.). The specific test results are compared in the following table:

blown film flat extrusion 对比.jpg

2) For textured HDPE geomembrane products:

The textured geomembrane is produced by blown flim process which is a one-step forming method by blowing nitrogen during production, so the finished product is a whole. It can be clearly seen from the samples produced by the Canada Solmax film blowing process that the rough surface is not easy to peel off. 


The flat extrusion process is a two-step forming method. First, the smooth geomembrane is produced, and then the rough surface is formed on the smooth surface by spraying rough particles. The finished product is not complete, and the rough points 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 indicators of the geomembrane. Under the same conditions, combined with the comparison of the above two production processes, from the perspective of actual construction and application, most projects will still use HDPE geomembrane materials produced by the blown film process.