Polypropylene Fiber: 6 Accurate Facts You Don’t Know
Standing in the sreet, the city is glutted with skyscrapers. Let’s get deep inside these giant buildings and dig into the tiniest being inside its concrete reinforced walls. For this blog, we specially mean pp fiber.
It is everywhere, omnipresent yet imperceptible like an invisibility cloak. If you are one of the engineering contractors, then polypropylene fiber is your old acquaintance. The pp fiber is a popular choice as additional material for pp fiber reinforced concrete. It is mainly used for interior and exterior walls.
As a secret weapon for preventing micro-cracks and reinforcing concrete walls, it is also economically affordable. Sometimes fiber mesh is also used, it is not only water-proof but also enhances the concrete’s integrity.
When it comes to concrete reinforcement, corrosion resistance, economy, and technical operation, fibers are always been considered ahead of steel rebar.
Here comes our leading role: polypropylene fibers.
What is pp fiber？
This seemly unremarkable tiny strand is made from petroleum-based thermoplastic polymers. Its source material is polypropylene gas, a by-product of oil and natural gas production. Polypropylene fiber is one of the lightest synthetic fibers in existence. It is incredibly resistant to most acids and alkali. In addition, the thermal conductivity of this substance is lower than that of most synthetic fibers. It is ideally suitable for cold weather wear.
How is pp fiber made?
These incredible polypropylene fibers can be made in the following ways.
First, the monomer polypropylene is extracted from crude oil in gas form.
This monomer is then subjected to a process called chain-growth polymerization to create the polymer polypropylene.
Once a large number of polypropylene monomers are strung together, solid plastic material is formed.
To make a usable textile, polypropylene resin must be mixed with a wide variety of plasticizers, stabilizers, and fillers
These additives are introduced into molten polypropylene, and once the desired substance is acquired, this plastic may be allowed to cool into bricks or pellets.
These pellets or bricks are then transferred to a textile factory, and they are remelted. This polypropylene is then formed into sheets, or it may be allowed to cool in molds.
These thin fibers are then cut into the desired shape and sewn or glued to create garments or diapers.
History and future of pp fiber
Polypropylene fiber was first made in 1951 by two chemists, J. Paul Hogan and Robert Banks. This was the first known attempt at making polypropylene.
Three years later, in two independent attempts in 1954, a German scientist and an Italian polymerized polypropylene into a crystalline isotactic polymer. These milestone events paved the way for the mass production of polypropylene. The use of polypropylene grew significantly in the following decades.
Today, polypropylene has become the vast material of choice for producers as well as manufacturers.
Three new trends of polypropylene fiber:
1. Pp fiber reinforced concrete for construction applications.
With the growing number of construction activities being undertaken such as airports, highways, roadways, expressways, dams, and many others, fiber-reinforced concrete sales are expected to grow rapidly over the forecast period. The surge in demand is likely to be witnessed globally, as such fiber reinforced concrete does not shrink when it is cold or enlarge in heat.
2. Textile innovations in pp fiber.
During the last few years, customers over the world is having increasing standards and visions for textiles. The vast demand has pushed the fiber industry to take on new changes and innovations. The sportswear market especially has witnessed a forceful rise in customer propensity
3. Strategic initiatives by global players will present lucrative innovation prospects.
Studies suggest that the synthetic fiber industry is the cause of over 20% of the industrial water pollution across the globe. To change this situation, several key players are attempting to rectify that by making targeted efforts to develop new strategies and innovations in pp fiber technologies.
Pros and cons of pp fibers
① Convenient to use!
Lower labor cost, easy to mix, and save time during construction as it is directly mixed with concrete, which can be conducted either on-site or factory. Besides, the addition of 0.1% by volume of pp fibers is proved effective in reducing the extent of cracking by a factor of 5-10.
② It saves money!
They are the plastic material with the lowest specific weight, lower amounts of material are required to obtain the finished product, which means the pp fiber is of great value for money.
③ Wear resistance!
It can achieve a good impact/stiffness balance and also conduct excellent chemical resistance to common solvents.
④ Restrain shrinkage cracking by creating a multi-dimensional network of tensile strength.
Slowing the bleed process and aiding in hydrating can be used as rebar and welded wire mesh replacement
⑤ Perfect material for thermal wear
PP fibers are very resistant to most acids and alkali. The thermal conductivity of pp fiber is lower than that of other fiber and can be used in thermal wear.
① It has a high thermal expansion coefficient which limits its high-temperature applications. This property prevents it from being ironed like cotton wool nylon when used in the textile industry.
② It is susceptible to UV degradation. It has poor resistance to chlorinated solvents and aromatics.
③ It is known to be difficult to dye as it has poor bonding properties. But after modification, it still can be painted.
④ It is easy to burn so it should be stored away from tinder.
⑤ It is susceptible to oxidation.
Applications of pp fibers
As we mentioned above, PP fibers are very resistant to most acids and alkali. The thermal conductivity of PP fiber is lower than that of other fiber and can be used in thermal wear. Polypropylene fibers are used in the following applications:
1. Industrial pavements&Industrial grounds.
Fiber reinforced concrete pavements are more efficient than ordinary cement concrete pavement. It has advantages like durable life, affordable in cost, economical environment, expanding load carrying capacity and impermeability to water.
2. Highly resistant concrete.
For this application we mainly referred to the polypropylene fiber reinforced concrete. Concrete without fibers is easy to crack due to plastic shrinkage and drying shrinkage. Polypropylene fibers are usually used in concrete to prevent these cracks from further expanding. They also reduce the permeability of concrete and thus reduce the bleeding of water. Some other types of fibers like steel fibers or macro fibers conduct stronger impact, abrasion, and explosive spalling resistance in concrete.
Compared to conventional concrete reinforcement, the usage of fiber reinforced concrete segment for tunnel linings has many highlights. The process of production is easier and the formation of cracks during handling and installation is evidently minimized. The segments are more durable because of their great impact toughness, resistance against corrosion, and cracking stresses. Their life circle is longer, their maintenance demands are small and, first and foremost, their production costs are drastically lower than for conventional steel rebar reinforced tunnels.
We used to put steel rebar into the bituminous concrete to prevent cracks and resist water bleed. But the biggest problem with this method is that steel rebar is always inclined to corrode,(see solution here) thus wear tire and on another way around, cause further pavement cracking.
5. Special mortars.
The application of polypropylene fibers in the mixture of mortars is able to resist the hydraulic shrinkage, relieve negative characteristics of the mortar during the hardening process, thus avoiding the formation and developing of cracks and fissures on the surface of the plaster.
6. Precast concrete.
Polypropylene fiber reinforced precast concrete is frequently used for concrete blocks, precast walls, staircase units, and poles. Precast with pp fibers is tougher, stronger, and less likely to create micro-cracks.
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