GB/T 9869.3-2025 is the third part of the series of standards for the determination of rubber vulcanization characteristics, which specializes in the detection method of rotorless vulcanizers. The standard specifies the test principle, instrument technical requirements, operation steps and the results of vulcanization characteristic parameters (such as scorch time, positive vulcanization time) of the method. It is suitable for the detection of vulcanization characteristics of various types of rubber. It can unify the detection method and ensure the accuracy of the data. It provides a reliable technical basis for the quality control, formulation optimization and vulcanization process setting of the rubber production process.