Throughout many years, participating in several projects, we have received frequent questions about the different products produced using fiberglass technology.
Is GRP the same as FRP? And what does RTRP mean? What kind of resins exists? What can we say about the types of fibers?
The fiberglass is obtained by flowing glass threads through a piece with very fine holes, obtaining a kind of consulate, which forms a mesh when interwoven with great resistance.
These glass wires are in a liquid state, at a temperature higher than 1000º, to then cool down, which provides flexibility for use as fiber, so that it can be used in the world of communications, as an optical fiber.
The fiberglass is the final result of the mesh joining that results with the application of the epoxy resin, which, at first, is liquid, but finally solidifies maintaining the shape for which the object was created or how it comes out of the mold.
This solidification process is carried out through the use of a catalyst and after a chemical reaction that requires maximum caution by those who carry it out as it is dangerous and volatile work.
Glass fibers are of five kinds:
Type E: with dielectric characteristics, it is used for the reinforcement of composites. Type R: with very good mechanical performance, it is used for the aeronautical industry, in airplanes. Type D: used in radars. Type AR: with great alkali resistance. Type C: resists chemical agents.
There are different types of fiberglass that are applied to polymers or plastics for reinforcement and use in everyday life, as well as aerospace, wind, rail, decoration, etc.
In general, fiberglass-reinforced polyester is a great thermal insulator, and inert to acidic substances, malleable and tensile resistant. As we have seen, it is used for many industries, being especially remarkable the realization of fiber optic cables, using fiberglass and telecommunications made by light signals, produced by LED's or through laser. Another application is the construction of water tanks, according to molds, surfboards, sailboats and other types of marine vessels.
Unfortunately, fiberglass products are not well known. If engineers deeply understood their advantages, they would recommend them much more than today! A good start is to clarify some concepts: The fiber-reinforced resin pipe (RTRP), is also known as GRP pipe (Glass Reinforced Plastic) or as FRP pipe (Fiberglass Reinforced Plastic) Due to its unique characteristics, it offers a range of advantages over pipes made of traditional materials currently used and, when properly designed and installed, provides optimum performance at minimal cost.
GRP is a “composite.” But what does composite mean? To make it clear, composite means "consisting of two or more different materials from each other." The compounds are an engineering material consisting of resin (the matrix) and fiber reinforcement. A liquid resin is combined with a fiber reinforcement in the manufacturing process, which is subsequently hardened by the curing process forming a solid laminate. There are many types of resins and reinforcements, and each of them imparts specific properties to the GRP product. To be more precise, there are at least 6 large "families" of resins used in the manufacture of GRP products. We can mention the following: Polyester; Vinilester; Modified acrylic; Epoxy; Phenolic resin; urethane resin systems.
Tell us what you need and we will tell you what we should use. If the corrosion resistance characteristic is a priority, a Vinilester resin should be used. If high strength is critical, epoxy is recommended. If the cost versus performance is in question, more commonly, polyester resin is used. Within the family of polyester resins, specific formulations are also used to obtain aesthetic properties or improve corrosion resistance, or resistance to high temperatures, etc.
Conclusion: the resin system is selected based on the functional and cost requirements of the product. What can we say about the types of fibers? There are many reinforcing fibers used in fibro-reinforced materials but mainly glass fiber is used. However, for high specific levels of performance, advanced fibers such as Kevlar or carbon fiber are used, which offer good properties (but of course with a higher price). Within the fiberglass family, there are many "varieties" of reinforcements. Depending on the process used and the resistance requirements of the product, the market offers many options.
Fiberglass can be applied with "random" orientation in the form of cut fiber. There are also lightweight fabrics, heavy fabrics, unidirectional fabrics, etc., which serve specific purposes in the design of composite materials. In addition to polyester resin and fiberglass, aggregates such as sand and other inerts such as calcium carbonate can be used in the production of GRP tubes. The aggregate that is added to the fiberglass/resin laminate is generally siliceous sand that meets special requirements. Such pipe is called Reinforced Plastic Mortar Pipe (RPMP). It is appropriate to mention that other inerts called “fillers” are also used to improve the different properties of the pipe (thixotropic agents, flame retardants, pigments, etc.).
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