1. Material composition
Polypropylene filament geotextile is mainly made of polypropylene (PP) filament fibers through a special production process. It is a non-woven material.

2. Material characteristics
High strength: Polypropylene filament geotextile is known for its high strength and high modulus. It can effectively resist external forces such as stretching and tearing in the soil to maintain the stability and integrity of the structure.
Good elasticity: Its instantaneous elastic recovery is better than PET fiber, but it is worse than PET fiber under long-term stress.
Poor heat resistance: The softening point is 130℃160℃, and the melting point is 165℃173℃. The heat shrinkage rate at 130℃ in the atmosphere after 30 minutes is basically the same as that of PET, both around 215%.
Good wear resistance: Polypropylene geotextile has good wear resistance and can maintain good integrity during use.
Light specific gravity: The specific gravity of polypropylene geotextile is only 0.191g/cm³, which is less than 66% of PET.
Good hydrophobicity: The moisture content of polypropylene geotextile is close to zero, and it hardly absorbs water. The moisture regain is 0.105%, which is about 8 times lower than PET.
Good wicking property: Although the hygroscopicity of polypropylene geotextile itself is very small (almost zero), it has good wicking performance, which can transfer moisture to the outer surface along the fiber axis.
Poor light resistance: The performance of polypropylene geotextile may be affected under long-term light.
Chemical resistance: It has good resistance to both acid and alkali, and its performance in this regard is better than PET fiber.
3. Application fields
Polypropylene filament geotextile has the advantages of strong acid and alkali corrosion resistance, good chemical stability, higher strength performance than similar geotextiles, large elongation at break, superior water permeability, and good composite fusion with polyolefin films. Therefore, it can be widely used in foundation reinforcement such as roads, railways, and airport floors, wall crack prevention, tunnel protection, sponge city construction, water conservancy anti-seepage and reverse filtration, landfills, tailings treatment, and industrial waste dumps. At the same time, it can also be used as soil and water conservation and ecological maintenance materials in ecological slope protection and other fields.

4. Specifications
The specifications of polypropylene filament geotextile mainly include unit area mass, thickness, amplitude, breaking strength, breaking elongation, CBR bursting strength, equivalent pore size, vertical permeability coefficient and tearing strength. The specific values of these parameters will vary according to different production standards and customer needs.

5. Production method
The production methods of polypropylene filament geotextile mainly include spunbond method, short fiber needle punching method, etc. Among them, the spunbond method is to melt the polymer particles or powder, then enter the extruder, and spin it into a continuous filament bundle through one or a series of spinnerets. Then use a rotating spinneret or control the airflow, change the conveyor belt speed, pass current and other methods to make the filaments form an irregular arrangement, and lay them on the conveyor belt to form a fiber net. The bonding of the fiber net is to use hot pressing or adhesive bonding, or mechanical reinforcement with needle punching when the filaments are not completely solidified, to form a continuous and uniform geotextile. The short fiber needle punching method is to make the short fibers into a cotton net through a carding machine or a waste cotton opening machine, and then cross-lay or directly form a cotton net with randomly arranged fibers by an air-laid machine to achieve isotropy when the cloth is formed. Then, a group or several groups of needle plates composed of a large number of needles are used to needle the fiber net, so that the fibers are entangled and squeezed together to form a non-woven fabric.

In general, polypropylene filament geotextile is a geosynthetic material with superior performance and wide application. It plays an important role in civil engineering.