Effect of molecular weight on packing during latex film formation

A UV-visible technique is used to study the evolution of transparency durin g film formation from latex particles. Latex particles with high and low mo lecular weight (HM and LM) polymethyl methacrylate (PMMA) are used to prepa re films. Two sets of films with different latex content were prepared from HM and LM particles separately, by annealing PMMA particles above the glas s transition temperature. Transmitted photon intensity, I,,, from HM and LM films increased as the annealing temperature was increased. The increase i n the transmitted photon intensity is attributed to the latex content (film thickness) for the annealed film samples. It is suggested that as the late x particles are packed (film thickness is increased) fewer voids or cracks are formed in the films, Positive and negative absorption coefficients are measured below and above 210 and 180 degreesC annealing temperatures for th e HM and LM films. Packing coefficients are obtained for films in various l atex contents. It is observed that LM particles are packed much easier than HM particles, (C) 2001 Academic Press.