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Determination of the Residual Strength of Polyamide Rope after Exposure to Weak Acids

The effect of acids on polyamide ropes was studied. The goal is to improve the safety of users performing the work at heights and using polyamide ropes or ropes with a low stretch core in their activities. Series of the experiments and calculations were carried out to determine the destruction of polyamide ropes subjected to chemical exposure considering the process development over time. Oxalic, formic, hydrofluoric, and citric acids are involved in the tests. They are more often found in everyday life as part of the detergents, so there is a high probability that the listed acids will get on the ropes. The time of their exposure to a section of the test sample with a length of 15 cm was 10 minutes in a room at the room temperature. After the contact with acid, the samples were kept for 85 and 208 days (stages 1 and 2, respectively). Then they were subjected to testing for static strength on a test bench for personal protective equipment. For the experiments, five rope samples were taken for each type of acid. During the process, presence of the defects was monitored. By visual inspection, it is difficult or almost impossible to detect the effects of acid exposure. When testing for flexibility, in all cases the test pieces of ropes differed from the reference piece. They have uncharacteristic rigidity and hardening of the rope body in the acid contact zone. The obtained data on breaking loads are averaged and presented in the form of the tables. The dependence of the residual strength on the type of acids was calculated considering the time factor.