DEVELOPMENT OF WATER-SWELLING RUBBERS BASED ON NATURAL RUBBER AND SODIUM CARBOXYMETHYL CELLU-LOSE

KOKGSY

Abstract

Studies were carried out on the development of water-swellable rubber (WSR) based on natural rubber (NR) as a material for packers. The rubber composition includes natural rubber with a sulfuric vulcanization system (sulfenamide C + stearic acid + zinc oxide). Sodium-carboxymethylcellulose (Na-CMC) was also introduced into the rubber compounds (RC) as a swelling agent. Na-CMC quantity was varied. WSR was obtained in two ways. The first is the traditional solid-phase method of production on rubber mixing equipment. The second - a mixture of hydrophobic and hydrophilic polymers was prepared beforehand by the liquid-phase combination of the aqueous suspensions thereof and the subsequent separation and drying of polymers mixture on the basis of which the RC were produced by the traditional solid-phase method. In both cases, the RC was prepared with mixer Brabender «Plasti-Corder®LabStation». Physical and mechanical parameters were determined on a breaking machine (INSTRON 5582 – 100kN), swelling characteristics were studied in distilled water. Due to the weak interfacial interaction between the hydrophilic polymer and the rubber, conventional WSRs have been found to have a low degree of swelling and a high degree of swellable polymer elution. The maximum degree of WSR swelling obtained in the solid phase in distilled water is 455% wt, with a Na-CMC content in rubber of 50% wt. An increase in the content of Na-CMC in RC leads to a decrease in the physical and mechanical properties and an increase in the degree of the water-swelling component leaching. WSR based on NR and Na-CMC, prepared in the liquid phase have a high degree of primary and repeated swelling and a satisfactory level of physical and mechanical properties. In distilled water, the maximum swelling degree of primary and secondary WSR is 905% by wt. and if the Na-CMC is in rubber 55% by wt 1730% by wt. respectively.