In addition to the raw materials and specifications of geomembrane there are many different, the production method is also divided into two, namely, blown film and film, corresponding to the process for the blow moulding process and extrusion process. The geomembranes produced by the two production processes have certain differences and have their own advantages, we will analyse the advantages and disadvantages of the two production processes.



I. Cast film



Laminating film, also known as cast film, is a non-stretching, non-directional flat extruded film produced by melt cast quenching, single-layer cast and multilayer co-extruded cast in two ways. Its production process is like this: first of all, the ingredients, will be high-density polyethylene particles, colour masterbatch, carbon black and other raw materials after a certain proportion of proportioning, mixing evenly into the silo, and then by the extruder will be raw materials temperature melting into a fluid, extruded by the screw extrusion in the film lip extrusion through traction through the steel rod or rubber roll forming cooling, which the size of the gap between the rollers is the thickness of the geomembrane, and finally hauling the cutting edge of the rolls.

The advantages of the film is high production efficiency, different thicknesses can be adjusted at will, low cost, high gloss geomembrane finished product, good flexibility, the minimum thickness can be done 0.2mm, the disadvantage is that the thickness is not uniform.


II. Blown film



Blown film production process is a three-layer co-extrusion blow moulding production method, the production process is the raw material through three heating screw feed into the blow moulding machine die head, in which heated and melted into melt, these melts in the pressure is extruded from the head, and in the position of the head of the formation of a cylinder, by compressed air through the die head upward blowing up to form a certain diameter of the film bubble, by the hauling rollers upward stretching and cooling to form a geomembrane, in the downward stretch after the curl, traction division by the spreading of the membrane. The geomembrane is then stretched and cooled downwards by the traction rollers to form the geomembrane, then extended downwards by curling, and then split into rolls by traction.

The advantage of blow moulding process is that the thickness of geomembrane is uniform, the tensile strength is high and the quality of the membrane is stable, the disadvantage is that the production cost is high, the price is not advantageous, the gloss and elongation are not as good as that of the laminating membrane.

In the case of using the same raw materials, the geomembrane produced by the two processes have their own advantages and disadvantages. Because of the low cost, good flexibility, tunnel engineering and civil engineering use more, while the blow moulding process because of the uniform thickness of the product, quality stability is higher, more suitable for landfills, reservoirs, tank farms, seepage control and other quality requirements of the project. But no matter which process, as long as in accordance with the standard production, the quality is up to standard, we go in accordance with the needs of the project to choose the right one can be.