Studies On Bromination Modification Of Natural Latax

The bromide modification of natural rubber latexand the production(NBR) were investigated. the effects PH of pre-stable nature latex, first reaction time, first reaction temperature, second reaction time and second reaction temperature on brominated degree were investigated. Solubility of BNR in toluene and xylene at different temperature was tested. The structure of BNR of brominated Natural Rubber were studied by Infrared Spectroscopy and Nuclear Magnetic Resonance. Thermal performance and mechanism of thermal degradation of BNR were studied by TG/DTG and TG/FTIR. UV-aging performance of BNR was studied by the UV-aging experiment. The general performance s and corrosion resistance of BNR film were studied.The results show that:PH of pre-stable natural rubber latex has significant influence on bromine content of BNR, when the PH of pre-stable natural rbbber latex less than 7, the bromine content of BNR was significantly higher than PH of pre-stable natural rubber latex more than 7, when PH of pre-stable natural rubber latex is 1, the bromine content of BNR is highest; the first step ot brominating natural rubber latex is very fast, bromine content of BNR arrives at 47.9% at 10min and changes little with reaction time increasing, when the first step temperature is between 10℃and 30℃, the bromine content of BNR changes litter with temperature increasing, bromine content of final BNR arrives at 70.4% at 30℃; bromine content of BNR increases with the increasing of the second step reaction time, and then leveled off after 6h; Bromine content of BNR increases with the second reaction step temperature increasing, but when the second reaction step temperature surpasses 40℃, bromine content of BNR begins descending; the solubility of BNR in the toluene and xylene is poor, at room temperature(20℃), BNR do not dissolve in the toluene and xylene, at 50℃, BNR completely dissolved in the toluene and xylene; bromine atom had grafted to the NR molecular chains, there were different kinds of C-Br vibration in Infrared spectra, and wave-numbers of C-Br vibration were,952cm-1,908cm-1,650-570cm-1, the bromination reaction may including replacing reaction and an addition reaction; BNR molecular weight is 43,361, much less than the molecular weight of natural rubber, the molecular weight distribution is very narrow as 1.00009479; thermal degradation of BNR is a two-step reaction. Dehydrobromination occurs during the first step, and the weight-loss ratio is close to bromine content of BNR, the second step degradation is stable atter 475℃, and there is a certain amount of sample is not degraded The thermal oxidative degradaton of BNR is a three-step reaction. Both degradation temperature and weight-loss ratio of first-step thermal oxidative degradation are close to those of thermal degradation, and the products are mainly hydrogen bromide but a little carbon dioxide. The products of second-step and third-step are carbon dioxide. The thermal oxidative degradation ratio reaches to almost 100%; the UV-aging property of BNR is not good, the color of BNR had a change affer lighting 1d, the color had a great change after lighting 4d, from white to yellow; CNR and BNR film have similar general performance, adhesion of BNR film was slightly better than CNR film, the impact strength worse than CNR film; BNR flim has a certain corrosion-resistant, but the corrosion-resistant of BNR film worse than CNR flim.