Emulsion polybutadiene

Between the 1920s when the initial commercial development of mbbery elastomers based on 1,3-dienes began (5—7), and 1955 when transition metal catalysts were fkst used to prepare synthetic polyisoprene, researchers in the U.S. and Europe developed emulsion polybutadiene and styrene—butadiene copolymers as substitutes for natural mbber. However, the tire properties of these polymers were inferior to natural mbber compounds. In seeking to improve the synthetic material properties, research was conducted in many laboratories worldwide, especially in the U.S. under the Rubber Reserve Program. 

E-BR . [Ameripol Synpol] Emulsion polybutadiene used for treads, extruded and molded goods, footwear, rolls. 

Sodium polybutadiene Emulsion polybutadiene Natural rubber Lithium polybutadiene... 

Sodium polybutadiene Emulsion polybutadiene Lithium polybutadiene Lithium polybutadiene Lithium butadiene-styrene, 89-11 LTP... 

The lithium-catalyzed butadiene polymers present an interesting correlation between microstructure and physical test properties. The most outstanding characteristic of the lithium metal-catalyzed butadiene polymers is their excellent low temperature properties. Figure 1 illustrates that, in compounded stocks, lithium-catalyzed polybutadiene reaches a Young s bending modulus of 10,000 pounds per square inch at a temperature 11 °C. below that for emulsion polybutadiene. 

The factors mentioned above adequately explain the superior cold properties of the lithium-catalyzed polybutadiene. Compared to emulsion polybutadiene, the lithium-catalyzed polybutadiene has more of the cis-1,4 structure and less trans-1,4 and 1,2 structures. All of these changes are in the direction to increase the relative amounts of more desirable microstructures, at least from the standpoint of cold properties. In addition, there is also a decrease in the predominant structure, trans-1,4, compared to the emulsion polybutadiene. Therefore, it would be less crystalline or orient less. 

Physical test properties on some cured rubber stocks prepared from lithium-catalyzed butadiene polymers are listed in Tables V and VI with appropriate controls. The results are only roughly indicative of the potential properties of rubbers made from lithium-catalyzed butadiene polymers because of the limited quantity of polymer available. The tensile data in Table VI indicate that compounded stocks from the lithium polymers are about equal or slightly inferior to the emulsion and sodium polymer controls in regard to these properties however, a hot tensile (lOO C.) on a cured compound from lithium polybutadiene was 325 pounds per square inch compared to 200 to 250 for an emulsion polybutadiene control. The internal friction of cured stocks from the lithium-catalyzed butadiene polymers is similar in magnitude to the emulsion or sodium polymer controls at 50 C. but higher at 100 °C. All lithium polymers, even those with low Mooney viscosities, gave cured compounds with high values of dynamic modulus. 

TABLE VIII Chain Structure of Emulsion Polybutadiene and SBR°... 

Table 7. Effect of Temperature on the Microstructure of Emulsion Polybutadienes ...

The emulsion polybutadiene process is similar to that described for emulsion SBR. 

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