Polybutadiene - continued temperature-dependence

Therefore, at room temperature Fluoro-PSB-II a thermoplastic elastomer with a soft polymer phase (fluorinated block) and a hard phase (PS-block), similar to the parental polystyrene-6-polybutadiene block copolymer. Depending on the relative volume fraction of both components and the continuity of the phases, the resulting bulk material is rubbery or a high-impact solid. 

Scalco, Huseby, and Blyler (8), Zosel (9), and Bergen and Morris (10). Prest and Porter (23) applied the same principle to homopolymer blends [poly (2,6-dimethylphenylene oxide)-polystyrene]. Recently some papers were published on triblock copolymers of styrene-butadiene-styrene and on their blends with polybutadiene (24, 25). Triblock copolymers can be considered heterophase material as the different constituent blocks are thermodynamically incompatible with each other, and, consequently, polystyrene domains are enclosed in polybutadiene (continuous matrix). The findings indicate that these systems are in general thermorheologically complex, so that the shift factor ar depends not only on temperature but also on time. These conclusions have been extrapolated to other two-phase systems. 

The sensitivity of the microstmcture to polymerization temperature depends on the Lewis base and the R value ([base]/[Li]) as shown in Table 11. Although the strongly chelating bidentate bases promote 1,2-polybutadiene microstmcture at low temperatures, they generally exhibit a dramatic decrease in their ability to promote vinyl microstmcture at elevated temperatures as shown in Table 11. This temperature dependence presents a particular problem in high-temperature processes, for example, commercial batch or continuous processes, in which medium vinyl polybutadienes are desired. ... 

---