# X-ray Diffraction Study of Metallized Polyethylene for Creating Heat Storage Systems
## 3 Results and Discussion
At the first stage of the X-ray diffraction study, a diffraction pattern of initial polyethylene granules and the pressed plate, which was heated and cooled according to the described regime, was obtained (Figure 4, Table 2). Figure 3: Calculation of the relative degree of crystallinity of polymers (the red line shows the division of the diffraction curve into amorphous and crystalline regions). The obtained diffraction pattern is typical for polyethylene and includes three reflections: the amorphous peak at a diffraction angle of about 20\({}^{\circ}\) and two crystalline peaks (about 21\({}^{\circ}\) and 23.35\({}^{\circ}\)). As noted earlier, polyethylene crystallizes with the formation of an orthorhombic crystal structure with lattice dimensions a = 7.406 A; b = 4.939 A; c = 2.547 A, the direction C coincides with the direction of the macromolecule. The presence of crystalline peaks is caused by X-ray diffraction from the (110) and (200) planes. The first peak is superimposed on a wide area of intensity, which is caused by the amorphous part of polyethylene and which corresponds to the predominant arrangement of polyethylene macromolecules in the amorphous state. If we compare the position of the maximum peaks in the diffraction pattern for polyethylene granules and the plate, it remains virtually the same, but the intensity of the peaks increases for the plate that has undergone one heating/cooling cycle. Analyzing the diffraction patterns of the metallized polyethylene granules and the plate that was obtained from them and underwent one cycle of heating and cooling (Figure 5, Table 3), it can also be noted that changes in the position of the reflection peak maximums of the crystal structure of polyethylene are insignificant. At that, the peaks responsible for the crystal structure of copper (43\({}^{\circ}\), 50\({}^{\circ}\), 74\({}^{\circ}\), 91\({}^{\circ}\)) appear on the diffraction pattern. The intensity of the peaks from the crystal structure of polyethylene is different for metallized granules and plates. The diffraction pattern of metallized granules is characterized by a \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Sample** & **Degree of Crystallinity** & **Position** & **Height** & **Width** & \
\begin{tabular}{c} **Size** \\ **L** \\ \end{tabular} &
\begin{tabular}{c} **Distance** \\ **d** \\ \end{tabular} \\ \hline \multirow{3}{*}{Initial PE granules} & \multirow{3}{*}{0.479} & 21.1 & 323.2 & 0.9 & 101.7 & 4.2 \\ \cline{3-7}  & & 23.4 & 101.1 & 1.0 & 89.2 & 3.8 \\ \cline{3-7}  & & 19.9 * & 65.8 & 5.4 & - & - \\ \hline \multirow{3}{*}{Plate made of initial PE granules} & \multirow{3}{*}{0.547} & 20.9 & 549.1 & 0.5 & 173.7 & 4.2 \\ \cline{3-7}  & & 23.3 & 141.6 & 0.7 & 133.0 & 3.8 \\ \cline{3-7}  & & 20.1 * & 75.3 & 4.1 & - & - \\ \hline \hline \end{tabular}
*–amorphous phase.  
\end{table} 
Table 2: Results of calculations of parameters of crystalline peaks and amorphous phase of polyethylene. Figure 4: Diffraction pattern of initial polyethylene granules and the pressed plate that underwent one heating and cooling cycle. lower intensity of peaks of the crystalline phase of polyethylene and by their greater width (Table 3). Obtaining the metallized polyethylene granules includes the stage of activation of the polymer surface as a result of their processing in a ball mill with finely dispersed zinc. The activation occurs due to the fixation of zinc particles on the surface of the granules during rotation of the ball mill and the impact action created by the presence of the grinding bodies in it. The result of the impact action on polyethylene granules is the accumulation of internal stresses, accompanied by the destruction of crystallites. The broadening of the peaks in the diffraction patterns of the polyethylene activated in a ball mill (metallized granules) is caused by a decrease in the crystallite size and the accumulation of lattice deformations [36].