Explore The Structure of Glass Fibers

  The high strength of glass fibers has aroused great interest among scientists and have studied the nature of its high strength, put forward a variety of hypotheses, trying to explain from the structure. Such as Tarasov and others from the polymer structure of glass, proposed that the fiber in the forming process, the molecular orientation occurs, the formation of chain-like structure. Another example is Barcheyev that glass fiber forming, the surface of the production of reinforced layer, the depth of 5 ~ 10nm, so that the fiber strength can be as high as 3000 ~ 3200MPa. With the deepening of the research, the above structure is different from the glass of the hypothesis have been proved to be inappropriate. At present, the more consistent view is that the glass fiber and glass in the structure of the same nature. Just because the glass fiber in the high-speed cooling conditions of forming, and therefore its microstructure is closer to the structure of the high-temperature melt, showing more loose, deformation, higher internal energy characteristics. This can be proved by the following facts.

  First, the density, refractive index, and modulus of elasticity of glass fibers appear to be smaller compared to block glass of the same composition. As the fiber diameter increases and the heat treatment process proceeds, these parameters gradually increase to values close to those of block glass.

  Secondly, it can be illustrated by tests of internal friction of glass and glass fibers. If a vibration process is induced within the glass, its mechanical energy is quickly converted into thermal energy even under conditions of complete isolation from the outside world. This conversion of energy and the consequent attenuation of vibration phenomenon is called internal friction. The internal dissipation of the glass material is characterized by the ability to resist deformation when mechanical energy loss occurs within it. It reflects changes in the internal structure of the glass and the motion of the masses. Measuring the internal dissipation of glass is one way to study the structural changes in glass. The quantitative difference reflected in the activation energy of the friction relaxation process in fine fibers points to the fact that the structure of the fiber is closer to the structure of glass at high temperatures, the fiber diameter becomes larger, the fiber size is closer and closer to the size of the block of glass, the structure tends to be compact, and the internal loss becomes smaller. Glass fibers after heat treatment, the characteristics of its relaxation spectrum to change. After heat treatment, the structure of glass tends to be close, and the internal dissipation becomes smaller.

  The facts described above prove that there is no molecular orientation in glass fibers, which is homogeneous with the structure of the block glass.