Preparation And Characterization Of Brominated Butyl Rubber From Latex

Bromobutyl rubber(BIIR)is the brominated modified product of butyl rubber.Because of its excellent air tightness and good aging resistance,ozone resistance,shock absorption and low water absorption,it is an irreplaceable raw material for the manufacture of tubeless tyres and some pharmaceutical products,belonging to the national strategic materials.The preparation technology of BIIR had been monopolized by foreign countries all the time,therefore it is the most important significance to study the production technology of BIIR and break the technical monopoly of foreign countries to promote the rapid development of our economy.In this paper,BIIR was prepared by butyl latex with bromine,KBr solution under acidic conditions and H2O2 as brominating agent respectively.The effects of peregal O,the system of pH,brominating agent,bromination time and bromination temperature on the bromine content of BIIR were investigated.The solubility and vulcanization properties of the BIIR products were also investigated.The thermal stability and degradation products of BIIR were studied by TG-FTIR and the thermal degradation kinetics of BIIR was simulated.The pyrolysis products of BIIR were studied by Py-GC-MS.The research results of the product are as follows:(1)When liquid bromine was used as brominating agent to prepare BIIR,the agglomerate phenomenon of rubber was easy to appear in the system,and the addition of peregal O could reduce the agglomerate of latex,but there was little effect on bromine content.If the acidity of the system was increased,the latex will be agglomerated.The bromination process of butyl latex was very rapid.The bromine content reached 2.39%in 4 min,and the bromine content almost no longer changed with the increase of reaction time and the bromine content of BIIR reached the highest value at 50?.(2)When KBr solution under acidic condition and H2O2 were used as brominating agent to prepare BIIR.The results showed that the bromine content increased with the increase of acid content,KBr solution amount,bromination temperature and bromination time.Furthermore,we found that the bromine content of BIIR prepared by this method was significantly higher than that of BIIR,prepared by liquid bromine as the brominating agent,and the BIIR obtained by this method was granular and almost lost the elasticity of rubber.(3)The solubility of BIIR prepared by latex method was very poor in organic solvents.It was completely insoluble in some weak polar solvents and only swelling in some strong polar solvents.The dissolution effect of organic solvent on BIIR was chloroform>cyclohexanone>tetrahydrofuran>phenol>acetone>toluene.The vulcanization time of the BIIR obtained by the latex method was too long and the vulcanization rate was too slow,so that there were low hardness and low productivity of the BIIR products.(4)TG-IR experiments shown that the degradation of BIIR in air atmosphere was degraded in two stages,namely the process of debromination of bromine-containing units to form HBr and the carbonization process of butyl rubber skeleton.In the air atmosphere,BIIR was degraded in three stages,namely the the process of debromination of bromine-containing units to form HBr,the simultaneous carbonation reaction and oxidation reaction of butyl rubber skeleton,and the oxidation reaction of residual carbon groups to form CO2.(5)The multi-heating rate method represented by Friedman,FWO and KAS found that the apparent activation energy,enthalpy change and entropy change of BIIR showed a decreasing trend with the increase of degradation rate,but the Gibbs free energy has almost no change.The single heating rate method represented by Coats-Redfem found that the thermal degradation mechanism of BIIR is closest to the three-dimensional diffusion(Ginstling equation)model.(6)PY-GC-MS study showed that the pyrolysis products of BIIR were mainly macromolecular compounds under low temperature conditions,and BIIR was further cleavage under high temperature conditions.The cleavage products are mostly small molecule compounds,and cyclization reaction occurs during the cleavage process to produce aromatic compounds and cyclic hydrocarbon compounds under high temperature conditions.