GB/T 8658-1998 introduces the refractive index determination method for the content of styrene in emulsion coalescence styrene-butadiene rubber. It is based on the principle of refractive index and specifies technical indicators such as the accuracy of special refractometers. Detailed description of the preparation process of raw rubber samples to ensure their uniformity. Standardize the determination process, covering solution preparation, refractive index measurement operations and data processing methods. Through this standard, the content of styrene can be accurately determined, providing a key basis for the production and quality control of emulsion coalescence styrene-butadiene rubber, and helping product performance optimization and market application.