Non-Destructive Testing of Glass-Fibre Reinforced Polymers using Terahertz Spectroscopy

We present THz time-domain spectroscopy measurements on glass-fibre reinforced polymers. The experimental set-up consists of a standard free-space THz spectrometer with photoconductive emitter and detector antennas driven by a femtosecond laser source. Single-point measurements to precisely obtain the THz properties of the sample are performed as well as two-dimensional images by scanning the samples perpendicular to the THz beam. We find that absorption coefficient and refractive index of the fibres significantly differ from that of the polymeric matrix material. Furthermore, the THz waves are strongly attenuated due to scattering off the fibres. The refractive index depends on the fibre concentration and orientation with respect to the linearly polarised THz radiation. With these results we can interpret THz images of a fibre reinforced polymer specimen. The THz images show the textures of the fibre network within the specimens and are compared with x-ray images.

[1]  Norbert Eisenreich,et al.  In-Line Monitoring of Polymer Extrusion Processes by NIR Spectroscopy , 1998 .

[2]  L. Piché,et al.  Ultrasonic behavior of polymer blends , 1995 .

[3]  Maya R. Gupta,et al.  Recent advances in terahertz imaging , 1999 .

[4]  R. Roe,et al.  Methods of X-ray and Neutron Scattering in Polymer Science , 2000 .

[5]  M. Nuss,et al.  Imaging with terahertz waves. , 1995, Optics letters.

[6]  H. R. Hamilton,et al.  Nondestructive Evaluation of Carbon Fiber-Reinforced Polymer-Concrete Bond Using Infrared Thermography , 2003 .

[7]  L. Alexander,et al.  X-ray diffraction methods in polymer science , 1969 .

[8]  M. Tani,et al.  Display Modes in Time-Resolved Terahertz Imaging , 2000 .

[9]  T. Ona,et al.  Non-destructive method for the quantification of the average particle diameter of latex as water-based emulsions by near-infrared Fourier transform Raman spectroscopy , 2002 .

[10]  Martin Koch,et al.  New Dimensions in T-Ray Imaging , 1998 .

[11]  Massimo Inguscio,et al.  Generation of tunable far-infrared radiation with a quantum cascade laser. , 2002, Optics letters.

[12]  Volker Trappe,et al.  Micro-mechanical properties of fiber composites characterized by X-ray refraction (Invited Paper) , 2005, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[13]  Antonio Nanni,et al.  Microwave detection of delaminations between fiber reinforced polymer (FRP) composite and hardened cement paste , 2002 .

[14]  Geoffrey A. Blake,et al.  Tunable far infrared laser spectrometers , 1991 .

[15]  Enrique Luis Lima,et al.  In-line evaluation of average particle size in styrene suspension polymerizations using near-infrared spectroscopy , 1998 .

[16]  V. Trappe,et al.  Intralaminar fatigue behaviour of carbon fibre reinforced plastics , 2006 .

[17]  J. C. Randall Polymer Sequence Determination: Carbon-13 NMR Method , 1977 .

[18]  David A. Ritchie,et al.  Terahertz quantum cascade laser as local oscillator in a heterodyne receiver. , 2005, Optics express.

[19]  Olga Zeni,et al.  Tera-Hertz radiation in Biological Research, Investigations on Diagnostics and study on potential Genotoxic Effects , 2004 .

[20]  D. Mittleman Sensing with terahertz radiation , 2003 .