Estimation of Emission Characteristics of Sulfur Gas from Rubber

Abstract

JIS K6234 4) 2) 2 2 1 3 EPDM (Ethylene Propylene Diene Monomer rubber) 4.3 5.8mm EPDM-A EPDM-B EPDM-C φ15mm 99.9% 1mm φ15mm SiC #1000 Estimation of Emission Characteristics of Sulfur Gas from Rubber by Rintaro MINAMITANI Silver, a typical material used in electronic devices, corrodes in sulfur gas emitted from rubber. To evaluate this corrosion damage of silver, we have established a new method for estimating the two emission characteristics of sulfur gas from rubber : initial sulfur-emission concentration and decrease rate of emission. Firstly, we used a long-term silver-corrosion test with rubber at 70−30 to investigate the emission mechanism and emission characteristics of sulfur gas from free sulfur, i.e., non-linked sulfur, in rubber. This investigation showed that the free sulfur in rubber is consumed by crosslink reaction between rubber chains and by sulfur-gas emission. The sulfur-consumption rate is controlled by the crosslink reaction at 70−50 , while it is controlled by sulfur-gas emission at 30. The emission characteristics at the temperature that the sulfur-consumption rate is controlled by sulfur-gas emission (i.e., 30) can be estimated by corrosion analysis considering sulfur-gas diffusion and the corrosion reaction of sulfur gas on silver. Secondly, we investigated the relationship between the amount of free sulfur and the emission characteristics. This investigation found that the amount of free sulfur can be calculated by integrating concentration of sulfur-gas emission. Given that result, we were able to establish a new method for estimating emission characteristics from the amount of free sulfur by chemical analysis and the initial concentration of sulfur-gas emission by a short-term silver-corrosion test with rubber.

A field life prediction model of electronic modules corroded by S8 gas released from rubber ducts in-vehicle engine rooms

“…Here we will examine the uncertainty of field corrosion life prediction considering a parameter that determines the field corrosion life of electronic modules. Figure 10 shows a calculation result of the remaining thickness ratios with a parameter β and using Equation (6). As Figure 10 shows, the corrosion life is longer if β is smaller.…”

“…Sulphur concentration of rubber duct in a vehicle decreases corresponding to the lapse of time in the field. Eventually, only the sulphur forming the cross-linking of rubber molecules will remain [6], as free sulphur is released from S 8 , it eventually disappears. We expressed the free sulphur concentration as an exponential function of the elapsed time, and defined the time for free sulphur concentration to decay to 63% as time constant ‘τ’.…”

“…In addition, when exposed to corrosive sulphur gas released from rubber components mounted in the engine room, there is a concern that the corrosive gas will permeate through the silicone to corrode the Ag wiring inside the housing [3]. With regard to studies concerning Ag corrosion forms and corrosion rate, studies based on experiments and analysis for the state of Ag exposure to corrosive sulphur gas have been conducted, revealing its quantitative corrosion behaviour [1,4–7]. However, no studies have been conducted that provide analysis of the corrosion life of in-vehicle electronic modules, and it appears no study has been conducted concerning prediction model for field corrosion life.…”