Abstract:
The objectives of this research cover investigation the effect of particle size of aluminium silicate on the physical properties of rubber vulcanizate, determination of particle size of aluminium silicate for the production of porous, low density rubber with applicable strength. Water glass (40% sodium silicate solution) with sodium oxide and silicon dioxide ratio of 1:3 was selected owing to high quantity of silicon dioxide for reaction. Aluminium silicate was formed in situ by reacting water glass at concentrations of 10, 20, 30, 40, 60, 80 and 100% with alum solutions at the pH values of 2.98, 3.08, 3.15 and 3.28 respectively in compound NR latex. The products were dried, compressed and analyzed for particle sizes of aluminium silicate, tensile strength and Shore A hardness. It was found that by compounding latex concentrate at low concentration of water glass and low pH of alum solution the particle size of aluminium silicate was 50-75 nm. Higher hardness was observed when particle size was smaller than 200 nm. Tensile strength was high when the particle size was smaller than 250 nm. When the compound was frozen in a mold, thawed, dried and vulcanized (temperature 150oC, time 1 hour) to produce a porous rubber medium, its hardness decreased (maximum hardness 39 IRHD) with its density. When the pores were filled with methyl mathcrylate which polymerized, using benzoyl peroxide, while the rubber was vulcanized the hardness was increased to 67 IRHD.