## 4 Conclusions  
In conclusion, by the introduction of FGi, highly oriented FGi/PTFE composites with enhanced TC are prepared. The in-plane orientation of the molecular chains, the primary cause of the material's anisotropic thermal characteristics, is confirmed by WAXS and SEM observations. Highly oriented molecular chains are demonstrated by EMD calculations to be the main contribution to the increase in TC. Notably, the FGi/PTFE composite with 0.5 wt% FGi exhibits excellent TC and dielectric properties with in-plane TC of 1.21 W\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\), dielectric constant of 2.06 (at 40 GHz), and dielectric loss of 0.0021 (at 40 GHz). Therefore, the introduction of FGi is a promising approach to enhance the TC of PTFE while maintaining the dielectric properties, which facilitates the application of PTFE composite substrates in high-frequency communication systems.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/ma18133010/s1](https://www.mdpi.com/article/10.3390/ma18133010/s1)]([https://www.mdpi.com/article/10.3390/ma18133010/s1](https://www.mdpi.com/article/10.3390/ma18133010/s1)), Figure S1: SEM image of FGi powders; Figure S2: The azimuthal scans and Herman orientation factor \(f\); Figure S3: Melt DSC curves; Figure S4: The models for various orientation degrees and crystallinity of FGi/PTFE composites; Figure S5: The in-plane TC of the model; Figure S6: Dielectric properties at various frequencies; Figure S7: Cross-sectional SEM images; Table S1: Comparison of mechanical and 10 GHz dielectric properties. References [48; 49; 50; 51] are cited in the Supplementary Materials.  
**Author Contributions:** Q.L.: writing--original draft, validation, investigation, formal analysis, data curation, visualization. X.C.: investigation, data curation. J.Z.: supervision, resources, project administration, funding acquisition. J.S.: writing--review and editing, supervision, resources, project administration, funding acquisition, conceptualization. W.C.: writing--review and editing, supervision, resources, project administration, funding acquisition, conceptualization. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Filler and Content** & **TC (W/(m\(\cdot\)K))** & **Dielectric Constant** & **Dielectric Loss** & **Reference** \\ \hline
30 vol\% AlN & 0.84 & 4.4@100 Hz & 0.0035@100 Hz & [14] \\
32 wt\% Al\({}_{2}\)O\({}_{3}\) & & & & \\ +21 wt\% GFs & 0.61 & 3.49@10 GHz & 0.0027@10 GHz & [45] \\
24 wt\% BNNs & 1.41 & 4.05@1 kHz & 0.0035@1 kHz & [46] \\
* +1 wt\% GNs & & & & \\
50 vol\% ZnNb\({}_{2}\)O\({}_{6}\) & & & & \\ +5 vol\% LCP & 0.88 & 6.46@15 GHz & 0.0075@15 GHz & [47] \\
0.5 wt\% FGi & 1.21 & 2.06@40 GHz & 0.0021@40 GHz & This work \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of TC and dielectric properties in PTFE-based composites.  
Figure 5: Dielectric constant and dielectric loss of FGi/PTFE composites at 40 GHz.  
**Funding:** This work was supported by the Open Fund of Hubei Longzhong Laboratory (2024 KF-04), the Chutian Talent Program Innovation Team, and Natural Science Foundation Innovation Research Team of Hainan Province (No. 524 CXTD431).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding authors.  
**Conflicts of Interest:** The authors declare no conflicts of interest.