A model for the pseudonetwork morphology is established to further study the influence of morphology on the toughness of polymer blends.The particle dispersion factor ( ξ ) is defined

where 0< ξ 1.For the particle dispersions of cubic lattice

well dispersed particles and pseudonetwork

the values of ξ are equal to

close to and smaller than one

respectively.A new equation for calculating the matrix ligament thickness of polymer blends with the pseudonetwork morphology is derived.The effects of other morphological parameters on the matrix ligament thickness are analyzed.The calculated vaiations indicate that the matrix ligament thickness reduces with the reductions of particle size

size distribution and particle dispersion factor and with the increase of particle volume fraction

respectively.It is demonstrated that the matrix ligament thickness of polymer blends with the pseudonetwork morphology is smaller than that with the morphology of well-dispersed particles when other morphological parameters of particle are identical.