Fast and easy analysis of polymeric samples

Importance of the Topic

Polymeric materials play a critical role in everyday products such as packaging, textiles, and industrial components. The rapid growth of homopolymers, copolymers, and block copolymers has led to an enormous variety of formulations, making fast and reliable identification essential for quality control and incoming goods inspection. Fourier transform infrared spectroscopy (FT-IR) with attenuated total reflection (ATR) offers a versatile, rapid, and non-destructive solution to address these needs.

Objectives and Study Overview

This application note demonstrates a streamlined workflow for the analysis of polymeric samples using a compact FT-IR spectrometer paired with ATR sampling. Key goals include confirmation of known polymers, differentiation of closely related materials, and library-based identification of unknown samples. The approach emphasizes ease of use, minimal sample preparation, and automated data evaluation.

Methodology

Samples in various physical forms—sheets, films, powders, liquids, and pastes—are placed directly on the ATR crystal without prior preparation. Infrared radiation penetrates approximately one micron into the sample surface, generating absorbance spectra characteristic of the polymer matrix. Typical analysis takes less than one minute, encompassing background measurement, sample acquisition, and automated evaluation via a software wizard.

Instrumentation Used

Key components of the setup include:

• Compact FT-IR spectrometer equipped with diamond and germanium ATR crystals
• One-finger clamp mechanism for reproducible pressure and contact
• PerformanceGuard online diagnostics for real-time monitoring of instrument performance
• OPUS software with guided workflow, quick compare functions, and comprehensive polymer libraries

Main Results and Discussion

The guided software wizard directs untrained users through background acquisition, sample measurement, and result interpretation. Three evaluation modes are demonstrated:

1. Quick comparison against a single reference or averaged spectra, yielding pass/fail confirmation with high correlation scores for known polymers such as polyethylene terephthalate (PET).
2. Multi-spectrum comparison to distinguish between related polymers (e.g., PC-ABS, pure polycarbonate, cellulose acetate) by ranking hits within a defined correlation threshold.
3. Library search using a dedicated ATR-polymer database, enabling identification of unknown samples within seconds and providing clear ranking of top matches.

For highly absorbing or dark samples, replacing the diamond crystal with a germanium element reduces penetration depth and eliminates spectral artifacts, resulting in sharper band definition and reliable identification of carbon-filled rubbers and other challenging materials.

Benefits and Practical Applications

The combined FT-IR ATR platform delivers:

• Rapid throughput with full analysis in under one minute
• No consumables or complex sample preparation
• Robust performance validated through automated qualification routines
• Intuitive operation via wizard-driven software, suitable for non-specialist personnel
• High reproducibility and consistent diagnostics for routine QC and incoming inspection

Future Trends and Applications

Emerging developments may include:

• Expansion of spectral libraries to cover novel polymer blends and additives
• Integration of artificial intelligence for predictive spectral interpretation
• Enhanced depth profiling and surface layer analysis through optimized ATR designs
• Remote monitoring and cloud-based data management for decentralized testing

Conclusion

The combination of a compact FT-IR spectrometer, interchangeable ATR crystals, and guided evaluation software establishes a powerful and user-friendly platform for polymer analysis. This solution streamlines incoming goods inspection, quality control, and unknown polymer identification, delivering reliable results with minimal training and infrastructure requirements.