Analysis of the Light Transmission Ability of Reinforcing Glass Fibers Used in Polymer Composites

Abstract

This goal of our research was to show that E-glass fiber bundles used for reinforcing composites can be enabled to transmit light in a common resin without any special preparation (without removing the sizing). The power of the transmitted light was measured and the attenuation coefficient, which characterizes the fiber bundle, was determined. Although the attenuation coefficient depends on temperature and the wavelength of the light, it is independent of the power of incident light, the quality of coupling, and the length of the specimen. The refractive index of commercially available transparent resins was measured and it was proved that a resin with a refractive index lower than that of the fiber can be used to make a composite whose fibers are capable of transmitting light. The effects of temperature, compression of the fibers, and the shape of fiber ends on the power of transmitted light were examined. The measurement of emitted light can provide information about the health of the fibers. This can be the basis of a simple health monitoring system in the case of general-purpose composite structures.

Self-Sensing Polymer Composite: White-Light-Illuminated Reinforcing Fibreglass Bundle for Deformation Monitoring

“…The reinforcing fibre bundle can transmit light if the medium surrounding it has a lower refractive index, therefore we needed a resin with a refractive index lower than that of glass to manufacture the specimens. Most resin datasheets do not include the refractive index of the resin, so we measured the refractive index of several resin systems [20]. Based on the results, we applied the MR3012 epoxy resin with a refractive index of 1.52 (Ipox chemicals, Germany) and the MH3122 curing agent (Ipox chemicals, Germany).…”

“…Although the diameter of the optical sensor is quite small (typically 125 microns), it is still an order of magnitude larger than the diameter of the individual reinforcing fibres, which creates an inhomogeneity in the composite, and a resin-rich area is formed next to the sensor, which can be a starting point of failure [14]. Because the refractive indexes of resins vary in a wide range [15], a glass fibre-reinforced composite can be made capable of transmitting light with specially prepared glass fibres built into a resin with a refractive index lower than that of the glass fibres [16,17,18,19,20,21], and the change in the intensity of the transmitted light can indicate damage to the composite structure. This phenomenon can be used for structural health monitoring; this makes another sensor—which impairs the integrity of the structure—unnecessary.…”

Introduction to Photonics: Principles and the Most Recent Applications of Microstructures

“…The silica as an optical waveguide is a strongly absorbing material for wavelengths above 2 µm [ 29 ]. This is due to multiphoton absorption that causes vibrational resonance; however, there are different glass materials that can be used to fabricate the optical fibers in which these materials can transmit light at a longer wavelength [ 30 ]. The crystalline materials and hollow fiber waveguides are good candidates to perform these kinds of transmissions [ 31 ].…”

Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO2

“…An overview describing different designs in terms of the performance of photobioreactors is given in a recent review article 4. However, 2D‐structured materials have disadvantages because of small light transmission, effects of reflection and refraction, and low surface area 5. The use of transparent glass sponges could overcome these problems.…”