Pyrolysis of Rubber with Antioxidant 6-PPD - CDS

Importance of the Topic

Pyrolysis-GC/MS analysis of rubber materials enables rapid identification of polymer composition and additive components in a single experiment. This approach is essential for quality control, material verification and failure analysis in industries relying on elastomeric products, notably automotive tires.

Objectives and Study Overview

The study demonstrates how a single pyrolysis run at 700°C can reveal the monomeric building blocks, antioxidant content and processing oils in tire rubber. It aims to illustrate the effectiveness of the technique for comprehensive compositional profiling of complex rubber matrices.

Methodology

Rubber samples were subjected to flash pyrolysis at 700°C for 10 seconds to thermally break down polymers into volatile fragments. The resulting pyrolysate was transferred directly into a gas chromatograph coupled with a mass spectrometer for separation and identification of compounds.

Instrumentation

1. Pyroprobe filament temperature 700°C, 10 second hold
2. Interface temperature 300°C, valve oven 300°C
3. GC column 5% phenyl, 30m x 0.25mm x 0.25µm
4. Carrier gas helium with 50:1 split ratio
5. Inlet temperature 300°C
6. Oven program start at 40°C (2 min), ramp 10°C/min to 300°C
7. Mass spectrometer for compound confirmation and structural elucidation

Main Results and Discussion

Initial peaks correspond to copolymer monomers butadiene and isoprene followed by their dimers. A distinct peak at 21.5 minutes was identified as the antioxidant 6-PPD (N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine) based on its mass spectrum (molecular weight 268). A late eluting unresolved region indicates the presence of hydrocarbon processing oil.

Benefits and Practical Applications

This method allows simultaneous determination of polymer composition, antioxidant identity and oil content from a single analysis. It offers rapid screening for quality control, additive verification and material provenance in rubber manufacturing and recycling.

Future Trends and Applications

Advancements in pyrolysis interfaces and high-resolution mass spectrometry promise improved sensitivity for trace additives and enhanced deconvolution of complex pyrolysates. Integration with automated data processing will further streamline routine rubber analysis.

Conclusion

Pyrolysis-GC/MS provides a powerful, concise analytical route to characterize rubber formulations, revealing copolymer monomers, antioxidants and oils in one experiment. This versatile tool supports research, quality assurance and forensic investigations of elastomers.

References

1. Wampler TP Temperature as a Sample Preparation Tool in the Analysis of Materials by GC-MS LC.GC 17 1999 S14