Study On Properties Of High Level Skim Rubber

Skim natural rubber latex is a byproduct obtained during the centrifugal concentration of natural latex. Skim latex has a low dry rubber content and a high proportion of non-rubber solids, and the rubber particles are smaller in size. It is difficult to coagulate, and it takes more processing time. Skim natural rubber has a low level in performance and only applies to rubber products, which need not have a high level in quality.After skim natural rubber latex being ultra-filtered and concentrated in the hollow fiber column, and reacted with alkaline protease and papain respectively, the enzyme-deproteinized skim natural rubber with rare non-rubber components was produced in order to improve its performance. In this project, the structure characterization and some properties of this enzyme-deproteinized skim rubber and the blending rubber, which were produced with blending and co-coagulation of enzyme-deproteinized skim latex and field latex, such as six indexes, stress relaxation, vulcanization, mechanical and aging properties, thermostability and dynamic mechanics properties were studied.The results show that six indexes of enzyme-deproteinized skim natural rubber achieve technical requirements of SCR-5after pure skim latex reacted with alkaline protease and papain in0.5-0.7phr respectively. When the content of enzyme-deproteinized skim natural rubber come to40%, the blending rubber achieve technical requirements of SCR-5, which were produced with blending and co-coagulation of enzyme-deproteinized skim latex and field latex. The crosslink density and mechanical property of skim natural rubber improved significantly after deproteinization. The thermostability of enzyme-deproteinized skim natural rubber is worse than pure skim natural rubber. The initial degradation temperature of skim natural rubber after reacted with0.5phr alkaline protease and0.5phr papain decreased by7.6℃and4.9℃respectively when the activation energy of thermal degradation decreased from176.01KJ/mol to158.38KJ/mol and164.53KJ/mol respectively. The glass-transition temperature of high level skim rubber is slight lower than pure skim rubber. The apparent activation energy of glass transition is130.47KJ/mol when skim rubber was reacted with0.5phr alkaline protease, and120.59KJ/mol when it was reacted with0.5phr papain.