Molecular weight effect on void closure and packing at different annealingtemperatures during film formation from hard latex particles

Latex particles with high and low molecular weight (HM and LM) poly(methyl methacrylate) (PMMA) were used to prepare two sets of films with various la tex contents separately. These films were annealed above the glass transiti on temperature. A UV-Visible (UVV) technique was used to measure the transm itted photon intensity, I-tr during film formation from latex particles. Tr ansmitted photon intensity from HM and LM films increased as the annealing temperature increased. A void closure equation was derived for I-tr by usin g the Vogel-Fulcher viscosity equation. It is observed that as the latex fi lm thickness, d, increased void closure constant. B, and viscosity increase d in both HM and LM films. For a given thickness, d, the lower viscosity of particles in HM films results in better packing than in LM films.