GB/T 15904-2018 in English

GB/T 15904—2018 Standard Overview

This standard specifies in detail the method for determining the content of polyisoprene in rubber and its products, and is applicable to a variety of rubber materials such as natural rubber, isoprene gum, balata gum and gutta-percha. Compared with the old version of the standard GB/T15904—1995, the new version has been optimized in many aspects, including adding safety warnings, adjusting reagent requirements and improving experimental procedures.

Comparison of major technical changes

Experimental principle and steps analysis

Polyisoprene is heated and digested in a mixture of sulfuric acid and chromic acid to produce acetic acid. After removing carbon dioxide by steam distillation, the remaining acetic acid is titrated with sodium hydroxide standard solution. The polyisoprene content is calculated based on the stoichiometric relationship.

Detailed explanation of experimental steps

1. Sample preparation: select appropriate method to prepare samples according to material type, and ensure that the thickness does not exceed 0.5mm. 2. Extraction process: use filter paper to wrap the sample and remove impurities according to standard extraction method. 3. Digestion stage: add chromic acid mixture and heat at controlled temperature for 30 minutes to ensure complete reaction.

Result calculation and correction

The polyisoprene content is calculated according to the formula: $$ W_p = \frac{0.0908 \times (V_1 - V_0) \times c}{m} \times 100\% $$ Where, $V_1$ is the volume of sodium hydroxide consumed in the titration test solution, and $V_0$ is the blank test value.

Comparative analysis of standard frameworks

Implementation suggestions

1. The laboratory should be equipped with equipment that meets the requirements and calibrated regularly. 2. Operators need to undergo professional training and be familiar with safety regulations.