Non-Destructive Evaluation of Polymer Composite Materials at the Manufacturing Stage Using Terahertz Pulsed Spectroscopy

Nowadays, composite materials are widely used in building and construction industry, in motor-vehicles, spacecrafts and aircrafts, and in biomedical science due to the ability of combining various consistent components for manufacturing composite materials with physical and chemical properties significantly different from the properties of each component. Polymer composite materials (PCMs) appear to be the most common type of composites. PCMs consist mainly of polymer binder reinforced with the glass-fiber-fabric. Although PCMs are widely applied, PCM manufacturing technology lacks the methods of non- destructive testing. In this paper we demonstrate that terahertz (THz) pulsed spectroscopy (TPS) appears to be a unique instrument for solving important problems of PCM manufacturing control. We experimentally demonstrate the efficiency of TPS for non-destructive control of PCM binder polymerization, since THz radiation is sensitive to changes of picosecond dynamics in media. Furthermore, we show the ability to detect the internal non-impregnated voids inside the PCM structure by means of THz time-of-flight tomography. These results highlight the potentials of TPS applications for non-destructive control of PCM manufacturing process.