Measurement of Molecular Weight Distribution of SBR and Prediction of Rubber Processability
Abstract This investigation on the origins of variable processability of emulsion SBR as measured by the BIT test established that no simple relationship exists between Mooney viscosity and processability, and that molecular weight distribution must be considered when producing to a BIT specification. By devising a sample preparation method directly from latex and the peak-height-ratio technique, a rapid method of estimating BIT from GPC chromatograms was developed. The method is suitable for process control. The mixing studies showed a general trend of increasing die swell with increasing BIT. The soluble rubber phase was found to have the same molecular weight distribution irrespective of the distribution at the commencement of mixing. It appears that die swell is influenced by variations in carbon-gel.