Pyrolysis-GC/MS and TGA as tools for characterizing blends of SBR and NBR

There is increased technological interest to use blends of various dissimilar elastomers in applications for which service, material availability, or cost of a single elastomer do not provide the necessary processing, vulcanizate, or economic properties. Properties of polyblends are sensitive to variations in the amounts of the individual polymers used. Therefore, there is a need for developing a variety of analytical tools that will enable the compounder to monitor the consistency of blend compositions. In this study, the feasibility of using pyrolysis-GC/MS and thermogravimetric analysis (TGA) to estimate the blend composition of SBR/NBR blends was investigated. Pyrolysis-GC/MS degradation products that are characteristic of each polymer were identified. The GC/MS peak areas were used to determine the blend composition. The blend compositions were estimated by TGA from the linear correlation between the polymer composition and the temperature required to pyrolyze a sample to a specific % weight loss. The results obtained by pyrolysis-GC/MS and TGA were compared to calculated blend ratios of SBR/NBR in order to estimate the accuracy of the test methods presented in this study.