Background and Objectives: The present study aimed to investigate the physical properties (Breaking strength and Elongation) of polyamide(nylon) yarns. The materials used in the structure of fishing nets, due to their nature, are capable of undergoing changes in the living and non-living environments where the target species and other related resources reside. A fisherman, when using fishing gear, must pay full attention not only to the selection of appropriate materials for a specific part of the fishing gear but also to other material properties such as strength, Elongation, flexibility, density, and various other interconnected properties.
Methods: Control samples were prepared from new and unused polyamide nets, and treated samples were prepared from 1, 2, and 3-year-old gillnets used in Hormozgan province. Breaking strength was measured using an Instron model TM-SM 5566 machine made in England.. A paired T-test was used for pairwise comparison of the physical properties of the threads during use.
Findings Based on the results, the control nets, with an average Breaking time of 20.1 seconds and Breaking strength of 270.94 ± 10.98 N, had higher Breaking strength and Breaking time compared to the 1, 2, and 3-year-old nets, with average tear times of (15.27, 12.175), and 11.18 seconds and Breaking strengths of (118.5 ± 16.99) N, (92.47 ± 14.16) N, and (73.73 ± 70.40) N, respectively. Paired T-test values showed a significant difference between the samples (P < 0.05). The elongation values(in percent) for four net samples – control nets and 1, 2, and 3-year-old nets, respectively – were (30.14 ± 3.36), (22.91 ± 1.25), (19.12 ± 5.62), and (16.78 ± 2.62) mm. According to the results of the elongation variable, all three treatments showed a significant difference with the control sample(P < 0.05). The Breaking coefficient values were also obtained as (43.86 ± 1.77), (19.18 ± 2.75), (14.96 ± 2.29), and (11.93 ± 1.19), respectively.
Conclusion: Therefore, considering the overall results of this research, gill nets, after fishing operations and use in water, show a significant difference in terms of Breaking time, Breaking strength, elongation, and Breaking coefficient compared to the control sample (P < 0.05).
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