# A Study on the Conductivity and Infrared Spectroscopy of Elastic Polymer Composite Materials
## 2 Materials and Methods
### Infrared Absorption Spectrum Analysis  
Figure 6 presents the infrared absorption spectrum of the base material, which exhibits four main absorption peaks at the following wavenumbers: 1030 cm\({}^{-1}\), 1600 cm\({}^{-1}\), 2260 cm\({}^{-1}\), and 2315 cm\({}^{-1}\). Figures 7 and 8 illustrate the infrared spectra of elastic polymer composite materials doped with varying concentrations of carbon powder, showing how these peaks shift or change with different doping levels. Figure 4: Solid energy gap model. Figure 5: Diamond lattice, for example, Si, Ge, C..., etc. (**A**) Tetrahedron bond in diamond lattice. (**B**) A tetrahedron bond. (**C**) Schematic two-dimensional representation of a tetrahedron bond [36]. Explanation: The points in Figure (**C**) depict the electrons shared within the covalent bond. As the doping concentration of carbon powder increases, the absorbance of lower energy chemical bonds decreases significantly. Consequently, absorption peaks at wavenumbers less than 1500 cm\({}^{-1}\) nearly vanish. The characteristic infrared spectra of the elastic polymer composite materials in this study are primarily attributed to various vibrational modes of chemical bonds, as explained in the following. Figure 6: The infrared spectrum illustration of the base material. Elastic polymer composite materials without carbon powder doping. Figure 7: The infrared spectrum illustration of elastic polymer composite materials doped with 4 M carbon powder. 2.4.1. The Infrared Spectrum Illustration of C-O Group  
The absorption peak corresponding to the C-O group stretching vibration, which is found at 1030 cm\({}^{-1}\), diminishes as the concentration of carbon particles in the substrate increases. This indicates an inverse relationship between the C-O group concentration and the carbon particle doping concentration. As the doping concentration of carbon powder rises, the concentration of C-O groups in the base material decreases. 2.4.2. The Infrared Spectrum Illustration of C=C Group  
In the characteristic region of the C=C group stretching vibration, the absorption spectrum typically features a single peak near the wavenumber of 1600 cm\({}^{-1}\) (6.25 \(\upmu\)m). The intensity of this peak is directly proportional to the doping concentration of carbon particles in the substrate. As the concentration of carbon powder increases, the number of C=C groups in the base material also rises, leading to a more pronounced absorption peak in this region. 2.4.3. The Infrared Spectrum Illustration of C\(\overline{\equiv}\)C Group  
At low doping concentrations of carbon powder in the substrate, the absorption spectrum displays a single, reduced absorption peak located at 2260 cm\({}^{-1}\). However, at higher doping concentrations, the spectrum reveals two distinct absorption peaks at wavenumbers of 2260 cm\({}^{-1}\) and 2315 cm\({}^{-1}\), respectively. 2.5. UV/VIS/NIR Spectroscopy  
Figure 9 illustrates the UV-VIS-NIR spectroscopy of the base material with varying concentrations of carbon powder doping. The UV-VIS-NIR absorption spectrum reveals a consistent pattern across different doping concentrations, with a common absorption peak at 325 nm. This peak is attributed to the transition of electrons from the valence band to the conduction band within the polymer chain of the elastic polymer composite materials [37]. As the concentration of carbon powder increases, a stronger absorption peak emerges at a wavelength of 2310 nm. Figure 8: The infrared spectrum illustration of elastic polymer composite materials doped with 40 M carbon powder. UV-VIS-NIR absorption spectroscopy provides insights into chemical bonding, particularly in relation to the electronic structures of polymers, including electronic orbitals, valence shells, and molecular configurations [38; 39; 40; 41; 42]. When the doping concentration of carbon powder in the base material is increased to 40 M, the conductive elastic polymer composite material exhibits a more pronounced absorption peak at 2310 nm.