According to the authors' previous experiences, organic lining coating materials, whose weight increases have not exceeded 3 mg/cm
2 after an immersion period of 100 hrs., may be commercially. Another experience showing which influence of a neutral solution is more severe, when the concentration of the solution is lower, gave a hypothesis in which the deterioration of materials depends possibly on the concentration or osmotic pressure of solution.
The detailed experiments leading to a new method for the evaluation of construction materials were carried out as follows:(1) in neutral conditions, such as aqueous solutions of NaCl, KCl, Na
2SO
4, or sucrose, the weight increases at 70°C of hard rubber, epoxy resin, polyvinyl chloride, natural rubber, “Neoprene, ” butyl rubber and nitrite rubber are dependent on the osmotic pressure of the solution, but independent of the kind of solute; and (2) in acidic or alkaline conditions, such as aqueous solutions of HQ, H
2SO
4, NaOH, or KOH, their weight increases are dependent on the kind of solute, and are generally greater than in a neutral salution having, the same osmotic pressure.
The apparent activation energies in these two conditions were calculated, and a deterioration mechanism was suggested in each cases.
A new evaluation method with some examples showing the application of new materials and the effect of changing composition of materials from the viewpoint of corrosion resistance was reported.
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