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Development of building fiber

wallpapers Energy 2020-02-18 >
 
Reinforced concrete with fibers is not a new idea of ​​the contemporary. It is an ancient method to add fibers to cementitious materials such as clay, lime, gypsum, and cement to improve its mechanical properties. The Chinese more than 3,000 years ago have learned how to incorporate straw into the earth to increase its hardness and resistance to rain. The technology of adding hemp root to lime or gypsum has also been applied for more than 2,000 years.
 
In 1963, it was found that adding a small amount of polypropylene fiber to cement paste and mortar can significantly improve its impact resistance. Since then, the British have added a small amount of film-cracked polypropylene fibers to concrete to make cement products such as pipe piles and wall panels. In the past 30 years, a series of synthetic monofilament fibers, such as polypropylene, polyester, polyethylene, nylon, polypropylene, etc., have been developed that can be incorporated into concrete/mortar. Among them, polypropylene fiber is widely used because of its moderate price, non-toxicity, aging resistance, chemical resistance, biodegradation resistance, stable quality, and easy control.
 
History of polypropylene fiber,
From the 1940s to the 1950s, it can be called the stage of innovation and the start of synthetic fibers and the rapid growth of manmade fibers. It is characterized by the emergence of many synthetic fiber varieties, especially the three most critical synthetic fibers, such as polyamide, polyester and polyacrylonitrile, which have been put into production in the 1950s. At the same time, humanmade fibers (mainly viscose fibers) have shifted from variety development to large-scale production, and the output has soared rapidly. By 1950, the output had reached 1.612 million tons, accounting for 94.4% of the total chemical fiber output.
 
From the 1960s to the mid-1970s, it could be called the period when artificial fibers tended to mature, and synthetic fibers proliferated. Although the output of humanmade fibers is still increasing, the rate of increase has stabilized since the mid-1960s (the average annual growth rate had dropped from 4.93% in 1950-1960 to 2.03% in 1960-1970). And the synthetic fiber transitioned from variety development to large-scale production, the output soared rapidly, from 702,000 tons in 1960 to 7.436 million tons in 1975, the proportion of total chemical fiber production increased from 20.9% in 1960 to 69.7% in 1975 And surpassed humanmade fibers for the first time in 1968. Especially polyester fibers are developing very fast. At this time, the chemical fiber industry has reached the stage of high-efficiency, automation, and large-scale production. Large-scale production plants have been continuously put into operation to meet the needs of actual life. The output has increased and has become a representative of industries with high economic value. It is amazing. It's progressing so fast.
 
Since the mid-1970s, the chemical fiber industry in economically developed countries has entered a mature stage, and the growth rate has begun to slow down. Still, developing countries and regions are in the growth stage. Therefore, since then, the development trend of chemical fibers has two characteristics. On the one hand, the use of synthetic fibers is continuously expanding, especially the proportion of decorative and industrial applications. Therefore, the total output of chemical fiber in the world continues to increase, but the rate of increase has slowed down significantly. The average annual growth rate had dropped from 9.41% in 1960-1970 to 5.36% in 1970-1980. Even human-made fibers even experienced negative growth for a time. The output of synthetic fibers in 2005 also showed a negative increase (down 0.3% from 2004).

 
On the other hand, competition in the manmade fiber market has intensified. To expand the use of products and increase its competitiveness, each fiber manufacturer attaches more importance to the development of new products and strives to master the initiative in market competition. The development of chemical fiber has entered a stage where the focus of development has shifted from "quantity" to "quality" and from conventional products to new products.

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