Quantification of phenol-formaldehyde curing resin in unvulcanized rubber blend using Py-GC/MS supplemented by TG-IR analysis

The curing bladder is the main element when producing a car tire. The tire curing bladder is a cylindrical bag concaved with a heat transfer medium, hot water, steam or gas during the vulcanization process. It is highly stressed due to the extremely high temperatures and pressures inside the pressing mold and it ensures the optimal process of vulcanization. Therefore, it is necessary to verify the quality of the tire curing bladder made of a suitable elastomer (rubber) blend. Analysis of rubber is an important technological operation in research and development in the automotive industry. The purpose of rubber blend analysis may be to confirm that the manufacturer or supplier owns or supplies a material according to the composition pattern, to clarify the cause of difficulties and failures during processing or to verify that the individual components of the rubber blend are correctly batched during technological operation “mixing”. Five analytical methods were used to determine the quality, presence and quantity of applied curing resin, specifically a combination of pyrolysis, gas chromatography and mass spectrometry and a combination of infrared spectroscopy and thermogravimetry. The concentration and percentage of the curing resin were determined from individual measurements and by comparing with reference samples (standards) from an industrial factory.