Anthony Jay Dias

Curative Migration in Rubber Compounds Containing Brominated Poly(Isobutylene-co-4-Methylstyrene)

Abstract 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...

Characterization and physical properties of new isobutylene-based graft copolymers

Abstract A number of isobutylene-based graft copolymers with different compositions are compared to several commercial thermoplastic block copolymers, such as SIS, SBS and SEBS, in terms of morphology and viscoelasticity. The backbone of these graft copolymers is a terpolymer (BIMS) of isobutylene, p-methylstyrene and p-bromomethylstyrene, and the side chains are either polystyrene or poly(2,6-dimethyl-1,4-phenylene ether). Graft copolymer synthesis, statistics of graft formation, and stress-strain properties are described. Overall, these graft copolymers exhibit unique shear dependent viscosity effects, such as rapid thickening (quick setting) at low shear and lower viscosity (better processability) at high shear, compared to linear triblock copolymers. The rheological behavior of these graft copolymers could be a key advantage for high-shear calendering, extrusion, hot-melt spraying, and injection molding.

Curing partially brominated poly(isobutylene-co-4-methylstyrene) elastomers with phenolic resins: Mechanistic investigation

The crosslinking of partially brominated poly(isobutylene-co-4-methylstyrene) elastomer 1 by phenolic resin crosslinkers was investigated. The curing was modeled using small molecule analogs of the elastomer and the phenolic resin. In order to mimic the conditions that prevail within the highly aliphatic rubber, the study was carried out in isooctane using catalysts such as coated ZnO that are compatible with such low polar media. In situ NMR analysis was used to probe the reaction between the molecular analogs, p-Isopropyl benzyl bromide was used as the elastomer analog and hydroxymethyl phenols were used as the resin analogs. Isotopic labeling allowed for independent yet simultaneous monitoring of the reactivity of the elastomer and resin analogs. The resin analog reacted with the elastomer analog via an electrophilic aromatic substitution, leading to the formation of a dibenzyl type ether and benzyl-phenyl type ethers as reaction intermediates. At lower temperatures the elastomer analog reacted with itself in a competing self-cure process that may be suppressed by increasing the homogeneity of the reaction mixture or by increasing the temperature of the reaction. The applicability of the mechanism was confirmed by successful model cure experiments involving a low molecular weight sample of elastomer 1 and the phenolic resin analog.