溴化方式对胶乳法溴化天然橡胶结构的影响

The Effects of Bromination Methods on the Microstructure of Brominated Natural Rubbers from Latex

为改善溴化天然橡胶(BNR)的溶解性能,在胶乳法的基础上改变溴化方式,以常规溴化方式和分步溴化方式分别制备了BNR。通过实验发现,体系溴浓度相同时分步溴化方式的溴含量比常规溴化方式高,而凝胶含量较低,所以分步溴化方式在甲苯中的溶解性能较好。通过傅里叶红外光谱对样品进行表征,并使用核磁共振对其微观结构进行了定性定量分析。红外光谱分析表明,2种溴化方式制备的BNR产物均发生了一定程度的溴加成反应和溴取代反应;核磁共振的分析证实了在体系溴浓度较低的情况下,与胶乳法常规溴化相反,胶乳法分步溴化的溴化过程主要以溴加成反应为主,少量发生溴取代反应。

In order to improve the solubility property of the brominated natural rubbers（BNR）from latex, BNR were prepared by changing the bromination ways 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. The latter showed much better solubility in the solvent of toluene.＂ The structure of the procured sample was characterized by Fourier transform infrared spectroscopy （FI＇IR）, and the mierostructures 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 methods; Contrary to the 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.