The Effects Of Bromination Method On The Structure Of Brominated Natural Rubbers From Latex

The brominated natural rubbers (BNR) has some excellent properties, such as peel strength, abrasion resistance, weatherability, corrosion resistance and so on. So, adding it to the coating can prepare the functional polymer materials with outstanding corrosion resistance and fire prevention ability. In the process of preparation, the primary problem is how to improve the solubility of BNR in organic solvent. In order to improve the solubility of BNR, firstly, observe bromine content and gel content of BNR products by changing the technology of preparing the BNR from latex; then, study the BNR products prepared by different bromination ways with different characterization methods and the reason why step bromination can increase the bromine content of the BNR product and reduce its gel content; finally, improve the solubility of the BNR products by the physical solubilization process.The brominated natural rubbers (BNR) were prepared from latex, and the effects of bromination technology such as dosage of peregal O, bromination time, bromine concentration and bromination method on bromine content and gel content of BNR products were investigated. The results show that bromine content and gel content of BNR products decrease with the increment of dosage of peregal O. When bromination time is5min, bromine content and gel content of BNR products reach to14.8%and12.7%, respectively. Gel content of the BNR product is14.8%as bromine concentration is only0.05mol·L-1, but it decreases to9.2%when step bromination adopted. The solubility of BNR products in the solvent of toluene increases with the decrement of gel content, and the BNR samples of which gel content less than15.7%are mostly dissolved in toluene. The result of the solubility of the BNR products with ultrasonication can explain that the ultrasound can be effective in improving the dissolution rate of the BNR and the solubility of the of BNR.BNR were prepared by changing the bromination way from conventional bromination to step bromination. Through the experiment, it was discovered that the bromine content of the latter was higher than the former, but the gel content was less under the same bromine concentration. So the latter showed much better solubility in the solvent of toluene. Through the analysis of the thermal degradation, thermostability of the BNR products with step bromination from latex reached the level of the conventional brominated BNR;The structure of the procured sample was characterized by Fourier transform infrared spectroscopy (FTIR), and the microstructures of brominated nature rubber were qualitatively and quantitatively analyzed by nuclear magnetic resonance (NMR). FTIR showed that there were both a degree of brominated addition reaction and brominated substitution reaction in the obtained BNR by two different method; Contrary to conventional bromination from latex, the analysis of NMR proved that the bromination process of step bromination from latex was mainly in the form of addition reaction, and only a small amount of the substitution reaction did occur.On the basis of preparing BNR from latex, preparing the BNR products with step bromination can reduce the gel content to some extent in this paper, which provides a new way of improving the solubility of BNR products.