Carbon Black At-line Characterization Using a Portable Raman Spectrometer

Importance of the Topic

Carbon black is a key reinforcing filler in tires, pigments, paints and other products. Rapid, non-destructive at-line analysis of its structure is essential for manufacturing quality control and process optimization. Raman spectroscopy offers molecular-level insight into carbon materials, making it ideal for real-time monitoring of carbon black production.

Study Objectives and Overview

This study demonstrates the use of a portable Raman spectrometer to characterize carbon black at-line. By evaluating the D-band and G-band features of sp2 carbon, the research aims to correlate Raman peak ratios with the degree of structural disorder and grain size in commercial carbon black samples.

Methodology and Instrumentation

• Portable i-Raman Plus spectrometer with 532 nm laser excitation and 4.5 cm−1 resolution
• Video microscope sampling system for precise focus on sample surfaces
• Back-thinned, TE-cooled CCD detector (−2 °C) for high quantum efficiency (up to 90 %) and low dark noise
• Laser power ~40 mW, integration time 120 s at room temperature
• BWSpec™ software employing airPLS algorithm for baseline correction and peak analysis

Main Results and Discussion

Raman spectra of three carbon black samples revealed distinct D-band (~1336–1337 cm−1) and G-band (~1574–1586 cm−1) peaks. Key findings:

• ID/IG ratio indicates disorder level: C1 (0.81), C2 (0.98) reflect moderate disorder; C3 (1.23) shows higher disorder.
• D-band position shifts with excitation wavelength; observed at 1337 cm−1 for 532 nm laser.
• ID/IG inversely correlates with crystallite size for grains >2 nm, enabling grain size estimation.

Benefits and Practical Applications

The portable Raman setup provides:

• Fast, non-destructive at-line characterization without sample preparation
• Real-time monitoring of carbon black structure during production
• Batch uniformity assessment through multiple sampling points
• Process control feedback to optimize product quality

Future Trends and Potential Applications

Advances in portable Raman technology are expected to drive:

• Integration into automated production lines for continuous quality monitoring
• Broader application to diverse carbon materials (nanotubes, graphene)
• Enhanced data analysis using machine learning for predictive process control
• Expanded use in safety, security, and material verification across industries

Conclusion

Portable Raman spectroscopy effectively characterizes carbon black by quantifying structural disorder and estimating crystallite size via the ID/IG ratio. The method’s speed, sensitivity and ease of use support its adoption for at-line and on-line process control, offering significant benefits over bench-top systems.

Reference

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