Paper number 855

COMPLEX PERMITTIVITY OF LOW LOSS THERMOPLASTIC COMPOSITES USING A RESONANT CAVITY METHOD

H S Ku1 J A R Ball2 E Siores3 and P Chan4

1Faculty of Engineering and Surveying, University of Southern Queensland, Australia and PhD Candidate, Swinburne University of Technology, Australia.
2Associate Professor and Head, Electrical, Electronic and Computer Engineering, Faculty of Engineering and Surveying, University of Southern Queensland, Australia.
3Professor and Executive Director, Industrial Research Institute Swinburne (IRIS).
Swinburne University of Technology, Australia.
4Faculty of Engineering and Surveying, University of Southern Queensland, Australia.

Summary The use of high energy rate joining of fibre-reinforced thermoplastic (FRTP) composites using microwaves has yielded promising preliminary results and more research is being carried out so that the technology can find its application in manufacturing industries shortly. Methods such as the dielectric probe and waveguide transmission have been successfully used to measure the dielectric constant of low loss thermoplastic composites but they cannot give reliable results when used to measure the dielectric loss. This paper describes a convenient laboratory based method designed to obtain , and hence loss tangent for low loss thermoplastic composite materials like glass fibre reinforced (33%) low density polyethylene [LDPE/GF(33%)]. The method is called the resonant cavity method and the schematic diagram of the set up and that of the cavity is depicted in Fig.1 and Fig. 2 respectively.
Keywords resonant cavity, perturbation, microwaves, Q factor, dielectric constant, dielectric loss and loss tangent.

Theme : NDE and Reliability ; Others

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