What Are The Cosmetic Properties of Fiberglass? （part 2）

  Glass fiber and other organic fibers, compared with a high degree of heat resistance, this is because the softening temperature of glass fibers as high as 550-750 ℃ and nylon only 232-250 ℃, acetate 204-230 ℃, polystyrene is even lower, only 88-110 ℃. Glass fiber strength at high temperatures is the total effect of two opposite effects that is, when the temperature rises, the thermal movement of the particles to enhance the molecular bond weakening strength will be reduced. But as the temperature rises, the particle displacement ability to enhance, especially on the surface, due to particle displacement, so that the top of the microcracks will be fused and blunted, the stress concentration is significantly reduced, so that the strength is increased. Glass fiber strength at high temperatures will not be reduced, but the strength of heat treatment will be reduced.

  It is of great practical importance to study the fatigue resistance of glass fibers under static loading, since the glass fibers are in tension during production and use. Composite users are also interested in learning about the fatigue properties of glass fibers and the factors that affect them. The authors believe that the way to improve the fatigue resistance of fibers is: ① through the improvement of the glass composition and changing the parameters of the fiber molding process, to reduce the number and size of microcracks on the surface of the fibers; ② fiber surface coating of hydrophobic substances to prevent adsorption of water into the microcracks.

 Glass fiber is brittle material. The study of its brittleness or flexibility in the manufacture of textile processing equipment suitable for it and the correct use of glass fiber products are of great practical significance. Flexibility of glass fiber, to a certain extent, can be used in the fiber loop, in the not yet broken when the radius to indicate. Can also be used before the fiber breaks, by the fiber winding the radius of the mandrel to indicate. Fiber product storage, use of media conditions will also affect the fiber flexibility. In general, the chemical stability of the fiber, the flexibility of the change is not large, and vice versa. As glass fiber is a brittle material, the elongation at break is very small, so its flexibility is small or brittle, which is its main disadvantage. In the textile processing must pay full attention to reduce the flex, especially the diameter of the mandrel of the flex fiber, to avoid fiber breakage due to the selection of improper diameter of the mandrel.

  Glass fibers absorb much less water than natural and man-made fibers. The amount of water adsorbed by the fiber has a strong relationship with the humidity of the air, and when the air humidity reaches 90%, the amount of water adsorbed increases very quickly. The ability of glass fiber water adsorption is also related to the time of storage in a humid medium. Dry glass fibers in a humid medium, the initial stage of water adsorption effect is the strongest, followed by adsorption of water slowly increased to the limit value. Although the water absorption capacity of glass fibers is very small, their surface area is so large that even small amounts of adsorbed water can lead to significant changes in certain properties such as mechanical and electrical properties. Therefore, in order to reduce the amount of water absorbed by glass fibers, they can be coated with water-repellent substances and the humidity environment in which the glass fiber products are stored can be controlled.

  Glass fiber has excellent sound insulation, acoustic performance. The sound absorption coefficient of glass fiber is large. As the frequency increases, its sound absorption coefficient also increases significantly. The sound absorption coefficient of various glass fabrics is related to the fabric structure, weave pattern, unit square meter mass, thickness, etc. In the case of very high frequency, the sound absorption coefficient of diffusion sound is about 60%. In the case of low frequency, the sound absorption coefficient of a wide range of changes, 0.7mm thick fabrics for more than 45% ~ 47%, and less than this thickness of "" fabric is only 17% ~ 32%. In the case of 500Hz, and the specimen was 90 ℃ angle of the directional sound flow of the absorption coefficient of 60% ~ 95%, in the case of high-frequency 2500Hz, the absorption coefficient of 78% ~ 95%. Because of the large sound absorption coefficient of glass fiber, its products can be used in a variety of acoustic equipment.