Tortusity factors

Tortusity factors have been calculated based on different models adopted by different theories. The ribbon and disk-like shapes of nanoclay have been considered in this study. Maji et al. [201] and Sun et al. [202] tabulated most of theories for permeability model equations. The brief descriptions of the theories are tabulated in Table 8. Figure 32 shows the experimental value of relative... 

The maximum value for the tortousity was 30 and the value for the tortusity of each sample was estimated from the formation factor. The formation factor was taken either from resistivity measurents or estimated from NMR measurements and the Myers pore-combination model [37]. A comparison of the estimated permeability correlations is given in Figure 3.6.9. The SDR model overestimates the permeability of low permeability samples and the Chang model underestimates the permeability of high permeability samples. The modified Chang model, Eq. (3.6.9), improves the estimate of permeability for both low and high permeability samples. 

Nielsen (1967) developed a simple model to describe the permeability of filled-poly-mers on the basis of tortusity argnment. In an ideal case where clay particles are fully exfoliated and uniformly dispersed along a preferred orientation (0 = 0°) in a polymer matrix, the tortuous factor x (defined as the ratio of the detour distance d to the thickness d of the specimen) becomes ... 

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