The Role of Polypropylene Fibers
Polypropylene fibers have two main uses in concrete:
1
Prevent plastic shrinkage cracks in concrete. During the setting and hardening process of concrete, surface water loss can lead to plastic shrinkage and cracks. Adding polypropylene fibers to concrete can prevent such cracks.
Due to the lower elastic modulus of polypropylene fibers compared to hardened concrete, the improvement in the crack resistance performance of hardened concrete (cracks caused by temperature stress or mechanical load) is limited, and the improvement in tensile and flexural strength is not significant, which has a certain degree of improvement in the toughness of concrete.
2
Improve the fire resistance of hardened concrete. Under the action of high temperature, polypropylene fibers will first soften and burn off, forming many pores in the concrete. The water vaporized by high temperature in the concrete can be discharged along these pores, preventing the formation of internal high pressure caused by water vaporization and causing the concrete to burst, thereby greatly improving the fire resistance time and rating of the concrete.
Polypropylene fiber woven bags have widely replaced jute woven sacks and become the most important basic packaging materials for grains, industrial raw materials, fertilizers, food, mineral sand, and coal. Their forms have long evolved from traditional pillow ladder style to barrel and column style. Due to its low density, light weight, conformability, and easy storage, it has even replaced some small containers.
There is a high demand for this type of product. Polypropylene nonwovens are also widely used in the packaging field, such as polypropylene nonwovens manufactured by melt blown method, which can be used for tea bags, insect repellent bags, and slow-release packaging in special occasions.
Polypropylene fibers are also very suitable for producing blankets. Pulling blankets are generally made of low twist polypropylene fibers. This blanket has properties such as insulation, insect resistance, easy washing, low shrinkage, and lightweight, making it suitable for both household and military use.
By applying polyethylene film or plasticized polyvinyl chloride, etc., to polypropylene fiber fabric using melt coating technology, protective cloth, windproof cloth, and mine exhaust pipe can be made. Polypropylene fiber fabrics coated with asphalt or tar can be used as substrates for ponds, while fabrics coated with other coatings can be used as protective covers and temporary rain covers.
