title: Permittivity measurement of thermoplastic composites at elevated temperature.
abstract: The material properties of greatest importance in microwave processing of a dielectric are the complex relative permittivity epsilon = epsilon'-jepsilon", and the loss tangent, tan delta = epsilon"/epsilon'. This paper describes two convenient laboratory based methods to obtain epsilon', epsilon" and hence tan delta of fibre-reinforced thermoplastic (FRTP) composites. One method employs a microwave network analyzer in conjunction with a waveguide transmission technique, chosen because it provides the widest possible frequency range with high accuracy. The values of the dielectric constant and dielectric loss of glass fibre reinforced (33%) low density polyethylene, LDPE/GF (33%), polystyrene, PS/GF (33%), and Nylon 66/GF (33%), were obtained. Results are compared with those obtained by another method using a high-temperature dielectric probe.
authors.affiliation: Faculty of Engineering and Surveying, University of Southern Queensland, Australia.
authors.forename: H S
authors.initials: HS
authors.lastname: Ku
authors.forename: B
authors.initials: B
authors.lastname: Horsfield
authors.forename: J A
authors.initials: JA
authors.lastname: Ball
authors.forename: E
authors.initials: E
authors.lastname: Siores
mesh_terms: D025802:Electric Capacitance; D017097:Electric Impedance; D006358:Hot Temperature; D008420:Manufactured Materials / Q000528:radiation effects*; D008422:Materials Testing / Q000379:methods*; D008872:Microwaves; D009757:Nylons / Q000737:chemistry / Q000528:radiation effects; D010969:Plastics / Q000737:chemistry* / Q000528:radiation effects*; D020959:Polyethylene / Q000737:chemistry / Q000528:radiation effects; D011137:Polystyrenes / Q000737:chemistry / Q000528:radiation effects; D011874:Radiometry / Q000379:methods*; D013696:Temperature
chemical_list: D009757:Nylons; D010969:Plastics; D011137:Polystyrenes; D020959:Polyethylene