Spatial variability of void structure in thin stochastic fibrous materials

Theory is presented for the distributions of local process intensity and local average pore dimensions in random fibrous materials. For complete partitioning of the network into contiguous square zones, the variance of local process intensity is shown to be proportional to the mean process intensity and inversely proportional to the zone size. The coefficient of variation of local average pore area is shown to be approximately double that of the local average pore diameter with both properties being inversely proportional to the square root of zone size and mean process intensity. The results have relevance to heterogeneous near-planar fibrous materials including paper, nonwoven textiles, nanofibrous composites and electrospun polymer fibre networks.