Hydrogenation of nitrile–butadiene rubber latex to form thermoplastic elastomer with excellent thermooxidation resistance

Abstract

Hydrogenation of nitrile-butadiene rubber latex was carried out using hydrazine and hydrogen peroxide, with copper sulfate as catalyst and without pressurized hydrogen and organic solvent. A special inhibitor was used during hydrogenation to reduce gel formation. Various hydrogenation conditions were studied. The gel content of the hydrogenation product can be reduced to ϳ15%, and hydrogenation degree can reach ϳ87%. The hydrogenated product was characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The hydrogenated product behaved as an oilresistant thermoplastic elastomer with excellent thermooxidation resistance, due to the absence of most double bonds and the presence of crystalline domains of polyethylene segments formed by hydrogenation of polybutadiene segments and nitrile groups. The higher the hydrogenation degree, the higher were the mechanical properties and thermooxidation resistance of the product. The product with a hydrogenation degree of 87% withstood thermooxidation quite well at 150°C for 65 h, maintaining ϳ98% of its tensile strength and 96% of its ultimate elongation.

Self-Cross-Linking Hydrogenated Nitrile-Butadiene Rubber Latex/Polyvinyl Chloride Emulsion Composite Film and Its Properties

“…Over the past few decades, many investigations on hydrogenating NBR directly in latex stage by diimide hydrogenation have been reported [11][12][13][14][15][16][17][18][19] . Although HNBR latex has a large amount of gel, HNBR latex is still a good raw material as latex.…”

Improving thermal and ozone stability of skim natural rubber by diimide reduction

“…The surface density of the copper ion catalyst on the particle surface was an important parameter in controlling the degree of hydrogenation of SBR. Xie et al [6] studied the diimide hydrogenation of NBR latex using copper ion and a hydrogenation degree of 87% was achieved after 6 h at 40 C for a mole ratio of hydrazine to carbon-carbon double bond of 2.5:1. Zhou et al [7] also studied hydrogenation of NBR latex by hydrogen peroxide and hydrazine with boric acid as catalyst and hydroquinone as inhibitor and 81.3% hydrogenation was achieved with a low gel fraction of 3%.…”

Hydrogenation of nitrile-butadiene rubber latex with diimide

“…In the low HD range, HE is modulated by the competition between the diimide production reaction (2) and the side reaction at the interphase (4). The catalysts provide catalytic effects for both reactions (2) and (4). The selectivity of the catalysts is then determined by the relative rates of the two reactions.…”

“…The diimide generation kinetics from the reaction between hydrazine and hydrogen peroxide were investigated to provide a fundamental understanding of the related hydrogenation reactions [3]. A suitable addition rate of reactants, [H 3 BO 3 ] 4 ] have previously been studied [2,4,5]. Various techniques have been investigated for overcoming gel formation during hydrogenation which has been the major obstacle for the diimide hydrogenation route to become a practical process.…”