Identification of an unknown vulcanization accelerator in vulcanized rubber using F-Search and the Additive MS library

Importance of the Topic

Identifying vulcanization accelerators in vulcanized rubber is essential for ensuring product performance and safety. Traditional solvent extraction GC/MS and general-purpose MS libraries often fail because the original accelerator decomposes during vulcanization. This creates a need for targeted analytical strategies that can trace decomposition products back to the parent accelerator.

Objectives and Overview

This study aimed to identify an unknown vulcanization accelerator in cured rubber by combining thermal desorption GC/MS with the F-Search software and a specialized additive MS library. The approach focused on minimizing interference from the rubber matrix and matching characteristic decomposition fragments to library entries.

Methodology

Thermal desorption GC/MS analysis was performed on 1.0 mg of vulcanized rubber. An evolved gas analysis thermogram guided the thermal desorption profile, using a furnace ramp from 100 to 340 C at 40 C per minute to limit base polymer breakdown. The GC column was UA-5(MS/HT), 30 m long and 0.25 mm ID with 0.25 um film, and the oven ramped from 40 to 320 C. Data were processed with F-Search against the additive MS library (P N PY-1114E-161).

Instrumentation

• Multi-functional pyrolyzer
• Auto-shot sampler
• MicroJet cryo trap
• Vent-free GC/MS adapter
• Gas chromatograph with UA-5(MS/HT) column
• F-Search software
• Additive MS library P N PY-1114E-161

Results and Discussion

Three distinct peaks in the chromatogram were observed and assigned as tert-butylamine, benzothiazole fragments, and 2-mercaptobenzothiazole based on retention indices and mass spectral matching. These fragments correspond to the decomposition products of N-tert-butyl-2-benzothiazolesulfenamide (TBBS). Although intact TBBS was not detected, the combined use of F-Search and the additive library enabled confident identification of the original accelerator.

Benefits and Practical Applications

The approach improves identification accuracy for vulcanization additives in complex polymer matrices. It supports quality control in rubber manufacturing, failure analysis, and additive monitoring. The method requires minimal sample preparation and leverages specialized libraries to overcome limitations of general MS databases.

Future Trends and Applications

Advances may include expanding additive libraries, integrating high-resolution and tandem mass spectrometry, and applying machine learning to spectral matching. These developments will enhance identification of novel or modified accelerators and other polymer additives.

Conclusion

This work demonstrates that combining thermal desorption GC/MS with targeted MS libraries and F-Search enables reliable identification of vulcanization accelerators from their decomposition products. The method offers a robust tool for rubber additive analysis.

References

• Shiono et al 20th Polymer Analysis and Characterization 2015