Influence of Vulcanizing System on the Properties of Rubbers Based on Ethylenepropylene Rubber

The article investigates the effect of vulcanizing systems of different activity on the vulcanization and elastic-strength properties of rubber compounds based on ethylene-propylene rubber Keltan . Were taken vulcanizing systems: a mixture of organic peroxide, sulfur and sulfenamide accelerator (1); a mixture of organic peroxide, sulfur and dithiodimorpholine (2); a mixture of organic peroxide, sulfur and thiuram accelerator (3); sulfur and sulfenamide accelerator (4). The vulcanization characteristics (maximum and minimum torques; times of onset, optimum and reaching the maximum speed of vulcanization) were evaluated. Elastic-strength (conditional tensile strength, elongation at break, hardness) properties of rubber compounds and operational (changes in conditional tensile strength, elongation at break after aging in air) were determined. It was found that the vulcanizing system (3) containing sulfur, peroxide in an amount of 7.0 parts by weight and thiuram accelerator imparts the best elastic and strength properties to rubber compounds and leads to their resistance to high temperatures.

WATER-SWELLING ELASTOMERS BASED ON ETHYLENE-PROPYLENE RUBBER

This paper is dedicated to the investigation of water- and oilswelling ability of the elastomeric material based on nonpolar ethylene-propylene rubber, modified by water swelling agents such as combination of copolymer acrylamide with potassium acrylate and sodium-carboxymethyl cellulose. It was found that the maximum volume increase of the sample recorded during it`s exposure in water and is equal 1250 %, in 10 % and 22 % aqueous solutions of sodium chloride is up to 280 % and 210 %, in oil and the Polyekonol-Flora drilling system 70 % and 80 %, respectively.

Structure and properties of recycled bamboo fiber reinforced chemically functionalized ethylene propylene rubber composites

Recycled bamboo fiber-reinforced chemically functionalized ethylene propylene rubber (R-BMBF/CF-EPR) composites have been developed by extrusion and injection molding by Palsule process without any fiber treatment and without compatibilizer. Scanning electron microscopy (SEM) shows good R-BMBF/CF-EPR interfacial adhesion in the composites, and Fourier transform infrared (FTIR) confirms that esterification and the hydrogen bonding between functional groups of CF-EPR and of R-BMBF impart this interfacial adhesion. Mechanical, dynamic mechanical, and thermal properties and the effect of water absorption on tensile properties of the composites have been evaluated. Tensile properties of the 15/85, 25/75, and 35/65 R-BMBF/CF-EPR composites are higher than those of CF-EPR and increase with increasing R-BMBF in the composites. Storage modulus and loss modulus of the composites increase with increasing fiber contents in them but decrease with increasing temperature. Water-absorbed wet composites show thickness swelling and reduced tensile properties relative to the respective dry composites but higher tensile properties than the dry CF-EPR. Thermal stability and degradation of the composites is also reported.