Relative humidity effects

Once the durability testing of the fuel cells is finalized, the internal components are then characterized. For diffusion layers, some of these characterization techniques include SEM to visualize surface changes, porosimetry measurements to analyze any changes in porosity within the DL and MPL, IGC (inverse gas chromatography) to identify relative humidity effects on the hydrophobic properties of the DLs, contact angle measurements to observe any changes in the hydrophobic/hydrophilic coatings of the DL, etc. [254,255]. 

In Figure 6.6 the temperature and relative humidity effects are depicted for solvent composition DEA=0, MeOH=0.18, CHCl3=0, EtAc=0.82 (the point with the highest minimum resolution). In total this resulted in 3 different elution orders. These are caused by two changes of elution order. The first between strychnine and quinine, the second between heroin and caffeine. The interpretation is that this solvent composition does not result in a robust TLC separation. 

Tablets prepared with dicalcium phosphate dihydrate increased in crushing strength due to increasing temperatures (A,sir(s) ). The relative humidity had a negative effect on the SIR of crushing strength of the tablets prepared with dicalcium phosphate dihydrate, except for the tablets prepared with potato starch. Also a significant interaction between the temperature and relative humidity effect was seen (A3,sir(S) 0), indicating that the effect of the relative humidity on the SIR of crushing strength of dicalcium phosphate dihydrate tablets depended on the level of temperature and vice versa.

Fig. 14 Relative humidity effects on indoor air pollutants and human illnesses.

The diffusivity can be affected by concentration of water, but in most instances the transport of water is sorption limited. The temperature and surrounding relative humidity effects on uptake kinetics are usually more important than the water content effects. 

To carry out such an isoconversion study, one needs to know the amount of degradant formation as a function of temperature. Such studies will fall into two situations when one has no knowledge of the acmal stability of the sample, and when one has preliminary information. When no information is available, one can use average behavior. This approach is discussed further in conjunction with the combination of relative humidity effects (Section 6.4.3). If preliminary data are available (e.g., for repeats of formulations), the times ean be adjusted at any accelerated conditions to meet the isoconversion paradigm. For example, if a degradant has a specification limit of 0.50, and 0.25% was found at one week at 60°C (with... 

Westerman, P.W., White, G.M., and Ross, I.J., Relative humidity effect on the high temperature drying of shelled com, Trans. ASAE, 16 1136-1139,1973. 

Jiang, R., Kunz, R.H. and Fenton, J.M. 2005. Investigation of membrane property and fuel cell behavior with sulfonated polyfether ether ketone) electrolyte Temperature and relative humidity effects.. 7. Power Sour. 150 120-128. 

RH Function Based on Pore Distribution. Anotherway of expressing the relative humidity effect on metal migration is derived from the assumption that a surface or an interface between a film and a substrate can be imagined as consisting of a log-normally distributed pore-network in which water condensation will first occur in the smaller pores as the... 

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