Porous formation models

From the electron micrographs, assuming that PVAc particles in the latex are the same size, the formation model of the porous film from the latex film can be illustrated as in Fig. 3 [19]. When the latex forms a dried film over minimum film-forming temperature, it is concluded that PVA coexisted in the latex and is not excluded to the outside of the film during filming, but is kept in spaces produced by the close-packed structure of PVAc particles. 

Figure 3 Formation model of porous PVA film from PVAc latex.

For homogeneously doped silicon samples free of metals the identification of cathodic and anodic sites is difficult. In the frame of the quantum size formation model for micro PS, as discussed in Section 7.1, it can be speculated that hole injection by an oxidizing species, according to Eq. (2.2), predominantly occurs into the bulk silicon, because a quantum-confined feature shows an increased VB energy. As a result, hole injection is expected to occur predominantly at the bulk-porous interface and into the bulk Si. The divalent dissolution reaction according to Eq. (4.4) then consumes these holes under formation of micro PS. In this model the limited thickness of stain films can be explained by a reduced rate of hole injection caused by a diffusional limitation for the oxidizing species with increasing film thickness. 

Tang, L., Moores, K.A., Ramaswamy, C. and Joshi, Y., 1998, Characterizing the Thermal Performance of a Flow Through Electronics Module (SEM-E Format) Using a Porous Media Model, IEEE Fourteenth IEEE SEMI- THERMTM Symposium. 

Berkowitz, B., J. Bear, and C. Braester. 1988. Continuum models for contaminant transport in fractured porous formations. Water Resour. Res. 24 1225-1236. 

Porous silicon formation models have been reviewed (Smith and Collins 1992 Allongue 1997 Zhang 2001). A conceptual analysis has been attempted (Zhang 2004). Major theoretical contributions applying to macropore formation are listed in Table 3. 

We reconsider the circular well centered in Texas, but relax our steady flow requirement by modeling the transient flow of a liquid having m = 0, a viscosity of 20 centipoise, and a compressibility of 0.000015/psi. A 20% porous formation is taken, along with a permeability of 0.001 Darcy. 

An extension of this QC model, including tunneling probabilities between the confined crystallites and the bulk, has been developed [Fr6]. The QC model for microporous silicon formation, however, is still qualitative in character, and a quantitative correlation between anodization parameters and the morphology and properties of the porous structure is at yet beyond the capability of the model. 

The numerical simulations of the stress distributions are carried out on porous materials submitted to uniaxial loading. In order to check the validity of the numerical simulations, macroporous epoxies are prepared via the CIPS technique. Cyclohexane is selected as the solvent, thus resulting in the formation of a closed porosity, and the statistical distribution of the voids coincides with the random distribution of the model system. The structural characteristics of these materials prepared by curing at T=80 °C are summarized in Table 4. 

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