Research On Influence Factors Of Preparing Brominated Butyl Rubber

In this paper, brominated butyl rubber was prepared by solvent process, many influence factors of preparing process and product properties of brominated butyl rubber are studied, such as the effect of different of concentration of bromine,concentration of butyl cement,contact time,residence time on Mooney viscosity,unsaturated degree,weight percent of bromine and microstructure of brominated butyl rubbe。The results showed that, the weight percent of bromine increased with the increase of concentration of bromine and contact time, and gradually tend to a certain theoretical maximum. Meanwhile, Mooney viscosity and unsaturated degree all decrease with the the increase of concentration of bromine and contact time. By the synthetic analysis of changing disciplinarian of bromine content, Mooney viscosity and unsaturated degree, we know that: under condition of high intensity mixing of the cement and bromine, the ratio of moles of bromine to moles of incorporated unsaturation in the butyl rubber is about 0．85 to 1 and residence time is 0 to 30s, the bromine can be present in the brominated butyl rubber which we prepare in amount of preferably from about 1．5 to about 2．5 weight percent.Two kinds of major microstructure of brominated butyl rubber were discovered: secondary allylic configuration and primary allylic configuration, the former is on the guiding place. Isomerization occur during bromine reaction, that is mean secondary allylic configuration changes into primary allylic configuration. Through model compound establishment and quantum chemistry calculation, we know that energy of secondary allylic configuration is lower than energy of primary allylic configuration, so that secondary allylic configuration was produced with comparative ease. We also found that the bond length of C-Br in primary allylic configuration is shorter than the bond length of C-Br in secondary allylic configuration, so the bond energy of C-Br in primary allylic configuration is higher relatively, it is easy to show that primary bromine is more stable than secondary bromine.