EXPERIMENTAL-STUDY OF PARTICLE STRUCTURING IN VERTICAL STRATIFYING FILMS FROM LATEX SUSPENSIONS

Two independent interference methods, based on wavelength and intensit y measurements, are applied to establish the type of packing of latex particles contained within vertical stratifying films. The films are f ormed in a ring-shaped frame after its pulling out from a latex suspen sion. They exhibit a stepwise profile, which appears as a set of paral lel stripes of uniform intensity varying from stripe to stripe. Both i nterference methods allow a study of the stratification phenomenon ''i n vivo'', i.e. during the process of film drainage. To fit the data fr om each of these two methods, we assume a given type of particle packi ng, in our case hexagonal or tetragonal, and then we check which type is consistent with the data, In all cases the data indicate the presen ce of hexagonal packing and do not agree with tetragonal packing, The developed technique can be further applied to examine the particle str ucturing in stratifying films containing smaller particles, such as su rfactant micelles or protein globules. The results can be helpful for a deeper understanding of the stratification phenomenon and the underl ying oscillatory structural forces.