How to distinguish the quality of geomembrane（一）
How to distinguish the quality of geomembrane（一）
(一) About Material production process
In the production process of HDPE geomembrane, there are currently two production methods in the domestic and international scope, namely the blown film process and the flat extrusion process. At present, 85% of the existing geomembrane production lines and most of the new geomembrane production lines in the world 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 geomembrane:
The requirements of the geomembrane resin raw materials are different in two different production processes. The melt index of the resin material of the flat extrusion process is generally 0.11 g/10 min (test method ASTM D1238 Cond. E), and the melt index of the resin raw material of the blown film process is generally 1.0 g. /10 min (test method ASTM D1238 Cond. E).
This is because the blown film process has higher requirements on the resin raw materials, and the melt index of the raw materials is higher. The tensile film stretchability of the geomembrane products produced by this method is also better. The geomembrane products produced by this method are produced. The tensile and elongation properties are also better. From the actual construction level, the HDPE geomembrane with better tensile elongation performance can better stress the external loading load (landfill, heavy machinery, etc.).
2) For rough geomembrane:
The blown film process is a one-step molding method. The rough surface of the geomembrane is formed by adding nitrogen gas during production, and the finished product is a whole, and the rough spots are not easy to fall off.
The flat extrusion process is a two-step forming method. After the smooth geomembrane production is completed, the rough surface is formed on the smooth surface by spraying the coarse particles. The finished product is not a whole material, and the rough spots are easy to fall off, which greatly increases the possibility of landslide accidents. Sex, the consequences are unimaginable.
In addition, more importantly, the blown film process can produce rough surface geomembrane products with higher matte height by adjusting the nitrogen pressure and direction according to the different topographical requirements of different landfill projects. Larger, better slope stability and higher safety factor, so that it can better meet engineering requirements.
For example, in the standard index, the rough surface height of the rough geomembrane is 0.25mm, and the blown film process can produce 0.5mm (commonly used) and 0.75mm (usually used) rough geomembrane products, and the flat extrusion Due to the defects of the process itself, the process has great limitations, and the rough surface height of the rough geomembrane is uncontrollable. In addition, the rough surface of the rough geomembrane produced by the flat extrusion process and the film itself are not integral, and the rough spots are easily peeled off. From the past experience, the geomembrane products produced by the flat extrusion process are generally not recommended.
