An investigation of the effect of methyl cellulose and sodium polyacrylate on the hydrosorption properties of a vulcanisate based on chloroprene rubber*

The effect of hydrophilic additives – MC-2000 methyl cellulose and sodium polyacrylate – on the properties of a vulcanisate based on Neoprene W was studied. The rubber mixes were prepared in two stages: at the first stage, hydrophilic additives were introduced into the rubber; at the second stage, the remaining ingredients were introduced. Vulcanisation was carried out at a temperature of 150°C for 30 min. The viscosity of the rubber mixes, M, was measured at 120°C on an MVR 3000 Basic viscometer (MonTech), and the vulcanisation characteristics and vulcanisation rate, v, were measured on an MDR 3000 Basic rheometer (MonTech) at 170°C in accordance with ASTM D2084-79. From the results of these measurements it follows that, with the combined use of methyl cellulose and sodium polyacrylate, there is a synergistic reduction in M and in the vulcanisation rate of the rubber mixes. A vulcanisate containing both hydrophilic additives possesses the best hydrosorption properties and has satisfactory physicomechanical properties (nominal tensile strength, elongation at break, hardness, and tear strength). The values of these properties and their changes on exposure of the vulcanisate to distilled water (70°C, 24 h) meet the requirements laid down for water-swelling rubber sealing elements.