Analysis method for structure of zinc dialkyl dithiophosphate (ZDDP) additive in lubricating oil

The invention relates to an analysis method for the structure of a ZDDP additive in lubricating oil. The analysis method comprises the following steps: heating the lubricating oil containing the ZDDP additive to a temperature of 160 to 240 DEG C under the protection of inert gas; carrying out sampling at intervals within 0.5 to 6 h and subjecting obtained samples to infrared spectroscopic testing; measuring absorption intensity of the characteristic absorption peak P-O-C in an infrared spectrum of ZDDP at the position 1100 to 900/cm by using a baseline method; and establishing the curve of a decay rule of ZDDP so as to finally obtain analysis results. According to the method, since heat stability of ZDDP with different structures is different and the intensity of the infrared characteristic absorption peak is different with a decay rate of heat treatment time in the infrared spectrum, structural information of ZDDP is obtained through detecting the decay rule of the intensity of the infrared characteristic absorption peak under the condition of different treatment time; and the method is simple and convenient to operate and can provide an effective analysis means for development and application of a formula for the lubricating oil.