Effect of film thickness and particle size on cracking stresses in drying latex films

The stress at which latex films crack during drying was investigated using beam bending. Two systems were investigated: (i) poly(methyl methacrylate/butyl acrylate) particles cast as thin films to examine the effect of film thickness on cracking film stress and (ii) polystyrene particles dried as drops to investigate the effect of particle size. Results indicated an inverse relationship between film thickness and film stress, whilst film stress was shown to be independent of the original particle size. These outcomes were in good agreement with Tirumkudulu and Russel’s theoretical analysis [M.S. Tirumkudulu and W.B. Russel, Langmuir 21 (2005) 4938], albeit the measured stress values were almost twice the theoretical estimation