Cancels and replaces the first edition (1982). Specifies a method for the determination of the long polystyrene block content of raw uncompounded styrene-butadiene rubber (SBR) and raw uncompounded blends of block SBR. Not applicable to blends of block SBR with EPDM, IIR, CSM and other halogenated rubbers. The method is suitable for rubbers having block polystyrene contents in the range from 5 % (m/m) to 100 % (m/m).