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How much do you know about glass fiber reinforced plastic
August 11, 2022
Glass fiber reinforced plastics (internationally recognized abbreviations as GFRP or FRP) are a wide variety of composite materials with good performance and wide applications. It is a functional new material made of synthetic resin and fiberglass materialthrough a composite process, and has played an important role in the construction of the national economy.
What is FRP
Glass fiber reinforced plastic (FRP) is a composite plastic with glass fiber reinforced unsaturated polyester, epoxy resin and phenolic resin as the matrix material. As a kind of composite material, FRP has been widely used in aerospace, railway, decorative construction, home furniture, building materials, bathroom and sanitation engineering and other related industries due to its unique performance advantages. According to the different fibers used, glass fiber reinforced plastics are divided into glass fiber reinforced composite plastics (GFRP), carbon fiber reinforced composite plastics (CFRP) and boron fiber reinforced composite plastics. It uses glass fiber products (glass fibre cloth, fiberglass tape, fiber mat, fiberglass yarn, etc.) as the reinforcing material, and uses synthetic resin as the matrix material. Fiber-reinforced composites are composed of reinforcing fibers and a matrix. The diameter of the fiber (or whisker) is very small, generally less than 10 microns, and it is a brittle material that is easily damaged, broken and corroded. The matrix has viscoelasticity and elastoplasticity, and is a ductile material. The relative density of glass fiber reinforced plastic is between 1.5 and 2.0, which is only 1/4 to 1/5 of carbon steel, but its tensile strength is close to or even higher than that of carbon steel, and its strength is comparable to that of high-grade alloy steel. The tensile, flexural and compressive strength of some epoxy FRP can even reach more than 400 MPa.
Main disadvantages: 1. Small elastic modulus; 2. Poor long-term temperature resistance; 3. Low interlaminar shear strength. The main advantage: 1. Good corrosion resistance; 2. Good dielectric properties; 3. Good thermal properties; 4. Strong designability; 5. Excellent manufacturability.
FRP material has the characteristics of light weight, high specific strength, corrosion resistance, good electrical insulation performance, slow heat transfer, good thermal insulation, good transient ultra-high temperature resistance, easy coloring, and the ability to transmit electromagnetic waves. Compared with commonly used metal materials, it also has the following characteristics:
Since FRP products can be designed and composited by themselves according to different use environments and special performance requirements, as long as the appropriate raw material varieties are selected, they can basically meet the performance requirements of various uses for the products when they are used. Therefore, FRP material is a designable material variety.
FRP products, which are one-off when they are formed, are another distinctive feature that distinguishes them from metal materials. As long as the appropriate raw material laying method and arrangement procedure are selected according to the product design, the FRP material and structure can be completed at one time, avoiding the secondary processing usually required for metal materials, thereby greatly reducing the material consumption of the product and reducing waste of human and material resources.
FRP material is also an energy-saving material. If the manual paste method is used, the temperature during molding is generally carried out at room temperature or below 100°C, so the energy consumption for molding is very low. Even for those molding methods that use machinery, such as molding, winding, injection, RTM, injection, extrusion and other molding methods, since the molding temperature is much lower than that of metal materials and other non-metal materials, the molding energy consumption can be drastically reduced. This technology is made using chemical properties.
Compared with traditional metal materials and non-metal materials, FRP materials and their products have the characteristics of high strength, good performance, energy saving, great freedom of product design, and wide adaptability of products. Therefore, in a certain sense, FRP material is one of the material varieties with a wide range of applications and great development prospects.
my country's glass fiber reinforced plastic industry already has a certain scale, and has made great progress in terms of product variety and output, as well as in terms of technical level, and has played an important role in the construction of the national economy.
Molding There are many ways to form glass fiber reinforced plastics. Among them, there are the simplest and easy-to-learn manual pasting methods, and there are molding methods that are relatively easy to establish; there are also filament winding molding methods that must be specially designed and professionally manufactured; there are also some comprehensive injection, vacuum, pre-forming reinforcement materials or presets Several molding methods of padding; and advanced automatic molding methods controlled by computer programs designed and manufactured in order to achieve high performance indicators of products.
It can be seen that there are many methods of making and molding FRP products, and their technical level requirements are very different, and their requirements for raw materials, molds, equipment investment, etc. are also different. Of course, the batch and quality of the products they produce, Nor will it be the same.
Commonly used FRP forming methods at home and abroad include hand lay-up molding process, injection molding process, molding process, molding material molding process, filament winding molding process, coil molding process, bag press molding process, resin casting and injection molding process, RTM molding process, pultrusion molding process, sheet and pipe continuous molding process, enhanced reaction injection molding process, elastomer grease storage molding process, as well as bonding and joining technology, sandwich structure manufacturing technology, etc.
In the above-mentioned FRP production and molding technology methods, each technology has its own characteristics. When a production enterprise chooses and determines which process method to use, it needs to comprehensively consider factors such as the basic situation of the enterprise and the situation of the products produced, such as the batch and quality requirements of the production products, as well as the technical foundation and production capital of the enterprise.
If the enterprise intends to sign a batch of FRP tables and chairs, the FRP tables and chairs can be made by hand lay-up, molding and RTM processes. At this time, it needs to be determined according to the actual situation of the enterprise and the product in order to obtain the most suitable production. The relationship between inputs, product quality and economic benefits.
A thermoset polymer matrix material, or engineering grade thermoplastic polymer matrix material, must meet certain requirements in order to first be suitable for FRPs and ensure a successful reinforcement of itself. The matrix must be able to properly saturate, and preferably bond chemically with the fibre reinforcement for maximum adhesion within a suitable curing period. The matrix must also completely envelop the fibres to protect them from cuts and notches that would reduce their strength, and to transfer forces to the fibres. The fibres must also be kept separate from each other so that if failure occurs it is localized as much as possible, and if failure occurs the matrix must also debond from the fibre for similar reasons. Finally, the matrix should be of a plastic that remains chemically and physically stable during and after the reinforcement and moulding processes. To be suitable as reinforcement fiber material, fibre additives must increase the tensile strength and modulus of elasticity of the matrix and meet the following conditions; fibres must exceed critical fibre content; the strength and rigidity of fibres itself must exceed the strength and rigidity of the matrix alone; and there must be optimum bonding between fibres and matrix
Glass fibre
"Fibreglass reinforced plastics" or FRPs (commonly referred to simply as fibreglass) use textile grade glass fibres. These textile fibres are different from other forms of glass fibres used to deliberately trap air, for insulating applications (see glass wool). Textile glass fibres begin as varying combinations of SiO2, Al2O3, B2O3, CaO, or MgO in powder form. These mixtures are then heated through direct melting to temperatures around 1300 degrees Celsius, after which dies are used to extrude filaments of glass fibre in diameter ranging from 9 to 17 µm. These filaments are then wound into larger threads and spun onto bobbins for transportation and further processing. Glass fibre is by far the most popular means to reinforce plastic and thus enjoys a wealth of production processes, some of which are applicable to aramid and carbon fibres as well owing to their shared fibrous qualities.
Roving is a process where filaments are spun into larger diameter threads. These threads are then commonly used for woven reinforcing glass fabrics and mats, and in spray applications.
Fibre fabrics ( glass cloth, etc) are web-form fabric reinforcing material that has both warp and weft directions. Fibre mats are web-form non-woven mats of glass fibres. Mats are manufactured in cut dimensions with chopped fibres, or in continuous mats using continuous fibres. Chopped fibre glass is used in processes where lengths of glass threads are cut between 3 and 26 mm, threads are then used in plastics most commonly intended for moulding processes. Glass fibre short strands are short 0.2–0.3 mm strands of glass fibres that are used to reinforce thermoplastics most commonly for injection moulding. Roving is a process where filaments are spun into larger diameter threads. These threads are then commonly used for woven reinforcing glass fabrics and mats, and in spray applications.
Aramid fibres are most commonly known as Kevlar, Nomex and Technora. Aramids are generally prepared by the reaction between an amine group and a carboxylic acid halide group (aramid); Commonly, this occurs when an aromatic polyamide is spun from a liquid concentration of sulphuric acid into a crystallized fibre. Fibres are then spun into larger threads in order to weave into large ropes or woven fabrics (aramid). Aramid fibres are manufactured with varying grades based on strength and rigidity, so that the material can be adapted to meet specific design requirements, such as cutting the tough material during manufacture.
Carbon fibres are created when polyacrylonitrile fibres (PAN), Pitch resins, or Rayon are carbonized (through oxidation and thermal pyrolysis) at high temperatures. Through further processes of graphitizing or stretching, the fibres strength or elasticity can be enhanced respectively. Carbon fibres are manufactured in diameters analogous to glass fibres with diameters ranging from 4 to 17 µm. These fibres wound into larger threads for transportation and further production processes. Further production processes include weaving or braiding into carbon fabrics, cloths and mats analogous to those described for glass that can then be used in actual reinforcements.
