Depth-profiling of talc/polypropylene (PP) compounded polymers with 5, 10,
15 and 20% talc weight percents were examined to delineate concentration ef
fects on surface stratification. This was achieved by utilizing step-scan p
hotoacoustic spectroscopy (S-2 PAS) phase analysis to discriminate molecula
r concentration changes for each species across a distance of 9 mu m from t
he sample surface. From phase analysis results, it was determined that not
only does talc lie 1-2 mu m closer to the surface than PP, but a layering e
ffect results from an increase in talc concentration. This layering effect
results in depths 0-3 mu m becoming saturated with talc molecules at lower
talc concentrations, and layers 3-9 mu m showing evidence of saturation at
higher concentrations. At these higher concentrations and greater depths, i
t is postulated that PP is displaced by talc molecules giving rise to a bou
ndary layer consisting mostly of talc. (C) 2000 Elsevier Science Ltd. All r
ights reserved.