Abstract:
This research was to study the surfactant adsorption and polymer film formation of
polyisoprene and polystyrene on the surface of the carbonate fillers containing barium
carbonate, calcium carbonate and magnesium carbonate for rubber compound. Sodium
dodecyl sulfate (SDS) was used as the surfactant. The effects of pH of surfactant solution,
surfactant concentration and mole of initiator for polymer film formation on filler surface
were also investigated. The optimal condition of each filler was selected for modification
by admicellar polymerization. The modified fillers were charceterized with hydrophobicity test,
Furier-transformed infrared spectroscopy (FT-IR) to determine their functional groups,
scanning electron microscopy (SEM) to determine their morphology, and particle size analysis.
All results confirmed that the films of polyisoprene and polystyrene were successfully coated on
the surface of the studied fillers.
Moreover, the mechanical properties of natural rubber mixed with modified fillers
were examined and compared with those of natural rubber mixed with unmodified fillers.
The results showed that the natural rubber mixed with modified fillers had higher mechanical
properties than those of the natural rubber mixed with unmodified fillers. The comparison of
mechanical properties between the modified fillers with polyisoprene and polystyrene was also
investigated. It was found that the tensile strength and elongation at break of the polyisoprene
modified filler rubber compound were higher than those of the polystyrene modified filler
rubber compound
With the comparisons of mechanical property between the modified fillers, calcium
carbonate and magnesium carbonate had the improvement of all studied properties, while
barium carbonate had no improvement.