Effect of Mount Pinatubo volcanic ash on the mechanical properties of styrene-butadiene rubber vulcanizates

Mt. Pinatubo volcanic ash, collected from Porac, Pampanga, was screened at 32 mesh screen, wetground in a pot mill for 3, 5, and 7 days, and dried. The volcanic ash was characterized and compounded with styrene-butadiene rubber (SBR) vulcanizates. Mineralogical investigation of the volcanic ash showed the presence of feldspar, homblende, quartz, mica, and magnetite. The particle size of the volcanic ash ground for 3, 5, and 7 days ranged from 1440 to 4, 720 to 2, and 640 to 2 mum, respectively. The addition of volcanic ash did not significantly influence the mechanical strength of the SBR vulcanizates. Stress-strain curves of the volcanic ash-filled SBR vulcanizates showed a slight increase from that of the pure gum. As the particle size of the volcanic ash decreased, the tensile strength and elongation at break points increased. Crosslinking sites also increased with the addition of rubber. Furthermore, it was noted that the addition of diethylene glycol hastened the curing reaction without affecting the mechanical properties of SBR vulcanizates. (C) 2004 Wiley Periodicals, Inc.