The penetration time of acid solution to different fabrics is one of the index of safety with working wears which protect workers from skin injuries and chemical burns.
The penetration time is measured by an original apparatus which is specially made for the purpose, the apparatus being consisted of platinum electrodes, Wheatstone's bridge and a recorder with automatic potentiometer.
The results were as follows :
1) Each acid solution penetrating the different fabric samples showed characteristic patterns in its penetration behavior, and the charts prepared from the data thus obtained enabled the estimation of the penetration speed.
2) At twenty percent of the concentration, the order of the penetration speed (from the highest to the lowest) was-acetic, nitric, hydrofluoric, hydrochloric and sulphuric acids ; and at thirty five percent of the concentration, the order was-hydrofluoric, acetic, nitric, hydrochloric and sulphuric acids. The order depends on the values of surface tension and viscosity of the solution.
3) The shag of hydrophobic spun fabric resisted penetration of the acid solution at ordinary pressure, and this is caused by the increase of the contact angle in accordance to the enlargement of the contact area.
To sum up, it is confirmed that the penetration time depends on the surface tension, the viscosity of the acid solution, the contact angle of the acid solution to the fabric, and the temperature.
Since vinylon and nylon have no tolerance to such acids, special attention should be necessary to protect them from chemical burns.
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