The function and interrelation of the three elemen

2022-08-07
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The function and interrelation of the three elements of glass fiber reinforced plastics (I) glass fiber glass fiber is the main load-bearing part of glass fiber reinforced plastics. It can not only improve the strength and elastic modulus of glass fiber reinforced plastics, but also reduce shrinkage deformation, improve the thermal deformation temperature and low-temperature impact strength. For example, after 50% glass cloth is added to 306# polyester resin casting body. The tensile strength can be increased from 50MPa to 200MPa, and the tensile modulus can be increased from 3.9gpa to 14gpa

(II) synthetic resin

synthetic resin is the matrix of FRP, and loose glass fibers are bonded into a whole by it

resin mainly plays a role in transmitting stress, so resin plays an important role in the strength of FRP, especially in compression, bending, torsion and shear strength

as the resin is the matrix material, it has an impact on the elastic modulus, heat resistance, electrical insulation, electromagnetic wave transmission, chemical corrosion resistance, weather resistance and aging resistance of FRP. For example, the chemical liquid corrosion resistance and water resistance of FRP mainly depend on the performance of resin matrix. Generally, unsaturated polyester resin 197\e has good chemical corrosion resistance, while 1289e has good water resistance. Different types and brands of resins have different properties

the resin content also has an effect on the properties of FRP. Usually, the resin content is 20%-35%, which is related to the forming method and the variety of reinforcing materials. For example, for winding and molding, the resin content is low, while for hand paste molding, the resin content is slightly higher. The resin content of the strength layer is slightly lower, usually between 25%-40%; The anti-corrosion and anti-seepage layer has a high resin content, generally more than 50% of which is reinforced by glass cloth, and the resin content is lower than that of glass felt. When glass fiber surface felt is used as reinforcing material, the resin content can reach more than 85%

(III) interface

the so-called interface is the interface between any two-phase substances

the performance of GRP is not only related to the reinforcement and synthetic resin used, but also related to the quality and durability of the interfacial bonding between fiber and resin to a large extent

as we all know, glass fiber is a kind of cylindrical glass, and its surface is as smooth as glass, and a thin water film is often firmly adsorbed on the surface, which of course affects the bonding performance of glass fiber and resin. In particular, in the process of drawing and spinning, glass fibers are often coated with a layer of wetting agent in order to achieve the purposes of bunching, lubrication and elimination of static electricity. Most of this kind of wetting agent is paraffin, which is retained on the surface of glass fibers and acts as an isolation between synthetic resin and glass fibers, preventing their bonding. It can be seen that the interface has a great influence on the properties of FRP

problems in the interface need to be solved. For example, a layer of surface treatment agent is covered on the surface of the glass fiber, so that the glass fiber and the resin can be firmly bonded together. This method is a very effective way to improve the basic properties of FRP, and it is being vigorously studied and adopted at home and abroad. Practice has proved that glass fiber and its fabric, after being treated with surface treatment agent, not only improve the wear resistance, water resistance and electrical insulation of glass fiber, although this work is not the first time to incorporate carbon nanotubes into polymer composites, but also significantly improve the strength of FRP, especially in wet conditions

in addition, there are also interface problems between FRP and other materials or the FRP itself has been laminated and pasted for many times. For example, if FRP anticorrosive lining is applied to the inner layer of the metal tank, the electroplating effect is often poor. The inner surface of the metal tank should be cleaned, such as removing dirt, oil, water and rust layer. Sand blasting, acid pickling and other treatment methods are often used. If the metal surface is not well treated, the FRP lining will fail. Sometimes, there will be interface problems when the cured FRP layer is bonded with FRP. For example, if the layered curing process or FRP damage repair is adopted, the surface of the FRP layer needs to be treated. In addition to removing dirt, oil, water, etc., the surface also needs to be sanded. However, the performance of the glass fiber reinforced plastic layer depends on the operation of the computer servo system in order to improve the bonding area. Otherwise, the delamination defect will occur

it can be seen that the small piston is prone to damage and oil leakage, and the factors that affect the quality of FRP and its products, in addition to the two major components of glass fiber and resin, the interface is also very important. These three elements are indispensable. They are closely related and inseparable. Therefore, we call them three elements, which are summarized from long-term practice

experience tells us that fiber, resin and interface are the three elements for the success or failure of FRP products. It can be said that when accidents happen to FRP products, people can find the reasons from three factors. For example, the reinforced concrete fermentation tank in a brewery was originally lined with asphalt, which fell off after short-term use. The glass fiber reinforced plastic lining is adopted. Because the original concrete pool surface is not cleaned, it falls off and becomes invalid after pasting, resulting in huge economic losses. In order to reduce the cost and pursue high profits, some fiberglass plants even use the glass fiber produced by the clay crucible, and the resin of the fiberglass corrugated tile produced will fall off within half a year. Because the fiber surface pulled out from the clay crucible has not been treated, there is a layer of wax film on the outer surface of the glass fiber, which makes the resin unable to stick firmly. Through careful inspection, exposed glass fibers can be seen at the edge of the corrugated tile, one of which is very clean and can not be stuck with any glue. This untreated glass cloth cannot be used on FRP. If it is used, it must be dewaxed at high temperature. (end)

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