Preparation and microwave properties of $\text{TiO}_{2}/\text{PTFE}$ composites reinforced by mullite fibers

In this paper, flexible $\mathbf{TiO}_{2}/\mathbf{PTFE}$ composite materials with different mullite fiber content were prepared. The effects of mullite fiber addition on microwave dielectric properties, tensile properties and other physical properties of $\mathbf{TiO}_{2}/\mathbf{PTFE}$ composites were studied. The experimental results show that the dielectric constant of $\mathbf{TiO_{2}}/\mathbf{PTFE}=\mathbf{20/26}$ (wt%) composite material decreased from 8.2 to 4.82, and its dielectric loss was also significantly reduced, from $\mathbf{12.8\times 10^{-4}}$ drops to $\mathbf{8.11\times 10^{-4}}$ , when the content of mullite fiber increased from 0 wt% to 4.wt%. In addition, the tensile strength first rises and then decreases. Especially, when the mullite content is 2.wt%, the dielectric material obtains the strongest tensile strength $\mathbf{(14.75{Mpa})}$ . On the other hand, when the content of mullite fiber increased from 5.7wt% to 11.3wt%, the dielectric constant of $\mathbf{TiO2/PTFE=20/33(wt\%)}$ composites slowly decreased from 6.18 to 5.63, and the dielectric loss increased from $\mathbf{7.62\times 10^{-4}}$ increase to $\mathbf{9.33\times 10^{-4}}$ , whereas the tensile strength decreases from 19.63 Mpa to 12.68 Mpa. Compared with the traditional introduction of glass fibers to improve the mechanical properties of microwave composites, $\mathbf{TiO_{2}}/\mathbf{PTFE}$ composite reinforced by mullite fiber maintains relatively good microwave dielectric properties and tensile strength.