OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 3 2023 Ta b l e 5 Free vibration test results No. Number of Layers (Time Duration and % NaOH) Free – Free Condition (Natural Frequency (Hz) and Corresponding Damping Factor) 1 4 (30 minutes, 1 %) 75.493 0.06224 422.72 0.024813 1387.0 0.044182 2 4 (30 minutes, 4 %) 75.81 0.0468 427.06 0.0500 909.0 0.04479 3 4 (1 hour, 1 %) 76.55 0.068 484.78 0.066 1200 0.0706 4 4 (1 hour, 4 %) 77.837 0.055 494.30 0.038071 806 0.0377 No. Number of Layers (Time Duration and % NaOH) Free – Free Condition (Natural Frequency (Hz) and Corresponding Damping Factor) 1 4 68.4 0.0455 410.2 0.0353 1079.1 0.0364 Free Vibration Test The results of tests for free vibrations, carried out on a four-layer jute basket-weaved composite material are presented in Table 5. It is evident from the above study that surface treatment improves the vibrational characteristics of the composite. In addition, it is shown that changes in vibrational characteristics are only 3 %, which is not very significant, regardless of the increase in NaOH strength and the soaking time. The free vibration test has been performed on an experimental setup and are presented in table 5. There are three natural frequencies and associated with damping factor with the help of fitting circle was obtained from this experiment. The first mode of three frequencies for basket-weaved CM after treatment with 1 % alkali solution for 30 min was found as 75.493; 422.72; 1387.0 and is related to the damping factor 0.06224, 0.024813, 0.044182. The second mode of three frequencies for basket-weaved CM after treatment with 4 % alkali solution for 30 min was found as 75.81; 427.06; 909.0 and is related to a damping factor of 0.0468; 0.0500; 0.04479. The third mode of three frequencies for basket-weaved CM after treatment with 1 % alkali solution for 1 hour was found as 76.55; 484.78; 1200 and is associated with a damping factor of 0.068; 0.066; 0.0706. The last mode of three frequencies for basket-weaved CM after treatment with 4 % alkali solution for 1 hour was found as 77.837; 494.30; 806 and is associated with a damping factor of 0.055; 0.038071; 0.0377. FTIR Analysis FTIR was carried out to study the functional group in the composite. For FTIR analysis, a sample in the form of a powder was used, and the obtained data are shown in fig. 6. The existence of a peak in the region of 650–2,000 cm−1 indicates the presence of single and double bonds of carbon with nitrogen, carbon, and oxygen, according to the comparison of the FTIR graph above with the standard graph. Peaks in the 3,000 cm−1 range indicate the existence of the O-H functional group, which gives composites its hydrophilic character. This composite absorbs moisture, which limits its use in situations where people are exposed to water. Surface Morphology SEM images study was conducted to analyze t the interaction of the fibrous matrix with the polymer composite. SEM images of composite material are shown in in fig. 7. The nature of the interaction of the fibers and the matrix of the composite material is shown above. Fig. 7c shows the fracture of the matrix in the direction opposite to the applied force, indicating its fragility.
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