The emulsion polymerization of 2,3-dimethylbutadiene-1,3

✍ Scribed by Morton, Maurice ;Gibbs, William E.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1963
• Tongue: English
• Weight: 899 KB
• Volume: 1
• Category: Article
• ISSN: 0449-2951
• DOI: 10.1002/pol.1963.100010812

✦ Synopsis

Abstract

A study has been carried out on the kinetics of the emulsion polymerization of 2,3‐dimethylbutadiene‐1,3. The kinetic treatment of Smith and Ewart was applied for the direct determination of the absolute propagation rate constant k~p~. The following expression was obtained: k~p~ = 8.9 × 10^7^ exp {−9000/RT} liter/mole/sec. A previously developed treatment was applied to the determination of the relative and absolute crosslinking rates of 2,3‐dimethylbutadiene‐1,3. The results led to the following expression for the absolute crosslinking rate constant k~x~: k~x~ = 3.0 × 10^6^ exp {−14400/RT} liter/mole/sec. A comparison of these rate constants was made for the three dienes, viz., butadiene, isoprene, and dimethylbutadiene. The propagation rate constants were found to vary only by a factor of 2–3. However, the crosslinking rates were found to decrease considerably in going from butadiene to isoprene to dimethylbutadiene. This was attributed, mainly, to the decreased side‐vinyl content of the latter two monomers, compared to butadiene, as well as to the steric hindrance imposed by the presence of the methyl group.