Sequential compaction model

Two matrix flow submodels have been proposed the sequential compaction model [15] and the squeezed sponge model [11], Both flow models are based on Darcy s Law, which describes flow through porous media. Each composite layer is idealized as a fiber sheet surrounded by thermoset resin (Fig. 13.9). By treating the fiber sheet as a porous medium, the matrix velocity iir relative to the fiber sheet is given as (Eq. 13.5) ... 

In the sequential compaction model, once a ply is completely compacted, the adjacent ply may begin compaction. This model assumes that matrix flow normal to the fibers and along the fibers may be decoupled. Another critical assumption is that the matrix supports the entire... 

A good understanding of the detailed chemistry of oxidant formation makes it possible to construct more compact chemical models. These generalized or lumped mechanism models reduce the number of individual chemical reactions by combining similar or sequential reactions and ig-... 

In the squeezed sponge model [11,13], compaction is not necessarily sequential and the applied pressure is shared by both the matrix and the fiber bed. The fiber bed behaves as a rapidly stiffening nonlinear spring. Pressure in the fiber bed is a function of fiber bed compaction. The rate of change of the fiber volume fraction is related to the pressure drop... 

The analysis shows that the pores in the simple model fill sequentially. If we extend the results to the more complex situation of a powder compact with a distribution of pore sizes, the same behavior of sequential filling of the pores is expected to occur. The pores with the smallest coordination number will be the first to fill because such pores have high surface to volume ratio, so a given volume of liquid eliminates more solid-vapor interfacial area. If there is sufficient liquid, the pores with higher coordination number start to fill. However, the pore filling leads to a percolation problem, and the liquid might not have access to all small pores, so some may be empty while large pores start to fill. 

Scheme 8 Proposed model for water-soluble polyplexes with sequentially hydrophilic (polyanion) and hydrophobic segments (complex of polyanion and polycation). The bending or compaction of DNA are not taken into account in this scheme...

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