Abstract
In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% to 16 wt% with a step size of 4 wt%. The effects of CaTiO3 loading on the density, moisture absorption, thermal expansion, microstructure and microwave dielectric properties were investigated. As CaTiO3 loading content increased from 0 wt% to 16 wt%, the thermal expansion initially displayed a sharp increase, and showed a slight enhancement when the content of CaTiO3 exceeded 12 wt%. The density experienced a continuous decrease with the addition of CaTiO3. The moisture absorption displayed a steady increase with the increasing CaTiO3 loading amount. The changing of dielectric constant (er) and loss tangent (tanδ) were similar to that of the moisture absorption in a manner. Good dielectric properties with values of er = 11.60, tanδ = 0.002 were obtained in the PTFE matrix with 16 wt% CaTiO3 and 45 wt% TiO2.
Highlights
Ceramic powder filled polytetrafluoroethylene (PTFE) has been widely studied in fabrication of microwave devices because of its very low loss tangent and excellent chemical resistance
The density experienced a continuous decrease with the addition of CaTiO3
The changing of dielectric constant and loss tangent were similar to that of the moisture absorption in a manner
Summary
Ceramic powder filled polytetrafluoroethylene (PTFE) has been widely studied in fabrication of microwave devices because of its very low loss tangent and excellent chemical resistance. PTFE is a kind of high performance high performance thermoplastic polymer with excellent electrical properties. It has a low dielectric constant (εr = 2.1) and an extremely low loss tangent (tanδ = 0.0003) which are stable over a wide range of frequencies [1]. The disadvantages of PTFE are its high linear coefficient of thermal expansion (CTE = 109 ppm∙ ̊C−1) and low mechanical strength. The object of this work is to study the effect of CaTiO3 loading on the properties of TiO2 filled PTFE composites, such as density, moisture absorption, thermal expansion, microstructure and microwave dielectric properties. It is expected that this work will be useful in the applications of TiO2/PTFE substrate composites in practice
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