Quality Control and Failure Analysis of Rubber Samples

Importance of the Topic

Rubber materials are widely used in industrial applications and consist mainly of synthetic polymers. Ensuring consistent quality of incoming and outgoing rubber goods is critical to avoid equipment failure, safety risks, and production downtime. Fourier-transform infrared (FTIR) spectroscopy provides rapid chemical identity verification and contamination analysis, supporting both quality control and failure investigation.

Study Objectives and Overview

The application note demonstrates how FTIR spectroscopy, using compact and microscopy instruments, can be applied to:

• Verify the chemical composition of rubber samples such as O-rings
• Identify contaminants and inclusions responsible for material failures
• Create chemical images to map component distributions in micro-scale defects

Methodology

FTIR spectroscopy exploits material-specific infrared absorption patterns for identification and quantification. Two setups were employed:

• ALPHA II compact FTIR spectrometer with ATR modules for routine quality checks
• LUMOS II FTIR microscope for micro-scale analysis of defects and inclusions

The ATR technique allows direct measurement of solids and liquids with minimal sample preparation. Automated raster scanning in the microscope generates chemical images through cluster analysis and integration algorithms.

Used Instrumentation

• ALPHA II FTIR spectrometer with diamond and germanium ATR modules
• LUMOS II FTIR microscope for micro-sampling
• OPUS spectroscopic software for spectral library searches and chemical imaging

Main Results and Discussion

O-ring Analysis:

• A 7 mm O-ring spectrum measured with a germanium ATR module matched nitrile butadiene rubber (NBR) with high confidence (hit quality 924/1000).

Failure Analysis of Rubber Sample:

• Chemical images revealed white PTFE and polyamide inclusions within a black rubber matrix.
• Automated cluster analysis distinguished micro-scale contaminants not visible in the optical image.

Benefits and Practical Applications

FTIR spectroscopy offers:

• Rapid, non-destructive identification of rubber compositions
• Quantitative analysis of fillers and additives
• Reverse engineering of competitor materials
• Detailed failure diagnostics using micro-sampling and chemical imaging

Future Trends and Potential Applications

Advancements may include:

• Enhanced spectral libraries and artificial-intelligence-driven identification
• Higher spatial resolution for chemical imaging
• Integration with other analytical techniques for multimodal failure analysis
• Automated inline FTIR monitoring in rubber production lines

Conclusion

FTIR spectroscopy, combining compact instruments for routine checks and microscopy for detailed failure analysis, ensures robust rubber quality control and rapid identification of defects. Its versatility and minimal sample preparation make it a valuable tool in industrial and research environments.