Curative migration in rubber compounds containing brominated poly(isobutylene-co-4-methylstyrene)

Blends of elastomers are widely used throughout the rubber industry. Blends are frequently used to get a balance of properties which cannot be achieved through the use of a single elastomer. For example, poly(isobutylene-co-4-bromomethylstyrene) can be blended with highly unsaturated general purpose rubbers to impart unique barrier or dynamic properties and enhanced oxidative stability. The final properties of such a blend are the result of a complex series of compounding, mixing and curing stages. These stages profoundly impact the homogeneity of the mixed components which include: the polymers, the filler, and the curatives. It is important to develop tools to monitor the changes which occur during compounding. This paper details the application of static secondary ion time-of-flight mass spectroscopy (ToF-SSIMS) imaging to simultaneously map polymer phase information with specific chemical information. The paper will highlight the utility of ToF-SSIMS for the study of the chemical and physical changes occurring during elastomer compounding, Blends of poly(isobutylene-co-4-bromomethylstyrene) and general purpose rubbers were compounded with typical cure systems and studied under a variety of mixing conditions.