The Role of Polypropylene Fibers
聚丙烯纤维在混凝土中主要有两种用途：
Polypropylene fibers have two main uses in concrete:
1）防止混凝土出现塑性收缩裂缝。混凝土在凝结硬化过程，表面失水会导致塑性收缩和裂缝，掺加聚丙烯纤维的混凝土，可以防止这种裂缝。
由于聚丙烯纤维的弹性模量低于硬化混凝土，因此对硬化混凝土的抗裂性能（温度应力或机械荷载等作用产生裂缝）提高有限，对抗拉、抗弯强度提高也不大，对混凝土韧性有一定程度提高。
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）提高硬化混凝土的耐火性能。在高温作用下，聚丙烯纤维会先软化和烧掉，在混凝土中形成许多孔道，混凝土中被高温汽化的水分就可以沿这些孔道排出，防止水分汽化形成内部高压而使混凝土爆裂，从而大幅度提高混凝土的耐火时间和耐火等级
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.
聚丙烯纤维制成的编织袋广泛地替代了黄麻编织成的麻袋，成为粮食、工业原料、化肥、食品、矿砂和煤炭等最主要的基本包装材料，其形式也早已由传统枕型梯式向着桶型、柱型等多元化发展。由于其密度低、重量轻、随形、易储藏，甚至代替了部分小型集装箱。
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.
该类产品的需求量很大。聚丙烯非织造布在包装领域的使用也很多，如熔喷法制造的聚丙烯非织造布可用于茶叶袋、防虫剂袋及特殊场合的缓释包装等。
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.
聚丙烯纤维也很适合生产毯子。拉绒毯一般用低捻度的聚丙烯纤维制造。这种毯子具有隔热、抗虫蛀、易洗涤、低收缩和重量轻等性能，既适于家用，也适于军用。
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.
把聚乙烯薄膜或增塑聚氯乙烯等，用熔融涂层技术涂到聚丙烯纤维织物上，可制作防护布、防风布和矿井排气管。用沥青或焦油作涂层的聚丙烯纤维织物可作池塘的衬底，其他涂层的织物可作保持性盖布和临时遮雨布等。
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.
