FTIR Spectroscopy

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An analytical technique that uses infrared light to identify chemical bonds and functional groups in plastic materials by measuring their unique absorption patterns.

In Simple Terms

FTIR spectroscopy works like a fingerprint scanner for plastics. It shines infrared light through a sample and measures which wavelengths are absorbed, creating a unique pattern that identifies the polymer type and any additives present.

Why It Matters

Essential for resin traders to verify material identity, detect contamination, and ensure quality. Helps prevent costly mix-ups between polymer grades and identifies unknown materials in recycled streams or customer returns.

Technical Details

FTIR measures molecular vibrations at specific wavenumbers (4000-400 cm⁻¹). Different chemical bonds absorb at characteristic frequencies - C-H stretches around 2900 cm⁻¹, C=O stretches around 1700 cm⁻¹. Advanced techniques like ATR-FTIR allow direct analysis without sample preparation, making it ideal for routine quality control.

Real-World Examples

Incoming Resin Verification

A trader receives a shipment labeled as HDPE but FTIR analysis reveals PP characteristics, preventing a costly material mix-up

Contamination Detection

FTIR identifies PVC contamination in a recycled PET stream by detecting chlorine-related peaks, allowing for proper sorting

Additive Package Analysis

Comparing FTIR spectra confirms that a UV-stabilized PP grade contains the expected antioxidant and UV absorber additives