Quality Control and Failure Analysis of Rubber Samples

Importance of the Topic

FTIR spectroscopy is a critical tool for quality control and failure analysis of rubber materials. By providing rapid chemical identification and quantification with minimal sample preparation, it ensures the consistency and safety of industrial products and supports reverse engineering of competitor formulations.

Objectives and Study Overview

This application note describes approaches to incoming goods inspection and failure analysis of rubber samples. It focuses on the use of compact FTIR instrumentation for routine quality checks and microscopic techniques to locate and identify inclusions or contaminants in O-rings and other rubber components.

Methodology and Instrumentation Used

Ultraviolet–visible infrared spectra were recorded using attenuated total reflection (ATR) for bulk samples and FTIR microscopy for localized analysis. A diamond or germanium ATR crystal was employed to obtain surface spectra without extensive sample preparation. Automated raster scans created chemical images that visualize the distribution of compounds within defect areas.

Used Instrumentation

• Bruker ALPHA II FTIR spectrometer with OPUS software for routine ATR measurements
• Bruker LUMOS II FTIR microscope for micro‐scale analysis and chemical imaging

Main Results and Discussion

An unknown 7 mm O-ring was identified as nitrile butadiene rubber (NBR) by matching its ATR spectrum to a digital library with a hit quality of 924/1000. Microscopic failure analysis of a black rubber sample revealed white PTFE inclusions and polyamide fragments within the elastomer matrix. Cluster analysis of fully automated raster scans produced chemical images that highlighted contaminant distribution, including features invisible under visible light.

Benefits and Practical Applications

• Non-destructive analysis with minimal sample preparation
• Rapid identification of polymer types and fillers
• Quantification of individual components in complex mixtures
• Detection and spatial mapping of micro-scale defects and contaminants
• Support for routine quality control, failure investigation, and reverse engineering

Future Trends and Opportunities

Advances in spectral library expansion and chemometric methods will improve automated identification and quantification. Integration of FTIR imaging with machine learning and real-time process monitoring could enable in-line quality control. Developments in high-resolution detectors and nano‐FTIR may further enhance defect localization in advanced polymer materials.

Conclusion

Compact FTIR spectroscopy and microscopy provide versatile, reliable methods for ensuring rubber product quality and diagnosing failures. The combination of ATR measurements for bulk material checks and FTIR imaging for localized analysis addresses the needs of industrial QC, research, and failure analysis with high speed and precision.