Non-uniform Distribution of Carbon Black in Low Hardness NR/BR Blends

The non-uniform distribution of carbon black N550 in the low hardness NR/BR compound with a blending ratio of 50/50 was studied by using dynamic mechanical analysis(DMA)and transmission electric microscopy(TEM),and the effect of mixing procedure on the distribution of carbon black was investigated.The results showed that,the peak value of tanδdecreased linearly with the increase of the addition level of carbon black,which could be used to calculate the carbon black distribution in each phase of NR/BR blend.When the Mooney viscosity values of NR and BR were similar,there were two Tgpeaks in the DMA curves of NR/BR blend located exactly at the peaks of NR and BR respectively,which indicated that NR and BR were immiscible.It was found that carbon black N550 was more affinity to BR,and when all carbon black was premixed with NR,better distribution of carbon black in the NR/BR blends was obtained comparing with other mixing procedures,which could reduce the non-uniform distribution of carbon black.