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Polylactic acid

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Result No.: 20260612174423548435103 Owner: worbin Comments: 0
FTIR ANALYSIS REPORT

FTIR Spectrum Analysis Report

No.: 20260612174423548435103 Date: 2026-06-12 16:51:29 Reported by: FTIR.fun Contact: [email protected]

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Top15

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Top 15 candidates

Reference library candidates

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Based on the library matches and evidence above.

Conclusion

Polylactic acid

Material direction: Polylactic acid (PLA)
High confidence
Conclusion
  1. High-confidence direct evidence ties the 1738 cm⁻¹ peak to the carbonyl of PLA [3].
  2. Multiple direct and analogical literature sources assign the 1186–1042 cm⁻¹ region to C–O single bond vibrations in ester and carbohydrate systems, compatible with the PLA ester backbone.
  3. The intense band at 1738 cm⁻¹ is assigned to ester carbonyl (C=O) stretching and is supported by direct literature evidence for polylactic acid [3].
Evidence & interpretation
Evidence

Key evidence

Library lead candidate
Polylactic acid #746
Limitations

Evidence that limits the conclusion

  • Low-wavenumber bands (690 and 753 cm⁻¹) cannot be confidently assigned to specific PLA vibrations with the available evidence; they may represent skeletal modes or minor impurities.
  • The broad O–H absorption at 3501 cm⁻¹ could originate from absorbed atmospheric water; thus, its intensity may vary with sample handling.
Recommendation

Suggested next verification

  • Acquire a reference spectrum of pure PLA processed under the same conditions (e.g., ATR crystal, film thickness) to confirm the overall profile.
  • Use DSC or TGA to verify the characteristic glass transition (~55–60 °C) and melting point (~150–160 °C) of PLA.
  • If the O–H band at 3501 cm⁻¹ remains prominent after thorough drying, consider end-group analysis by NMR or titration to assess degree of hydrolysis or molecular weight.
Peak analysis

Detected peaks and interpretation

★ = Literature-supported peak assignment.

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Index Characteristic Wavenumber Absorbance Evidence One-line interpretation Citation Confidence
1 ★ 1088 1.00 Literature-supported assignment The band at 1088 cm-1 is assigned to C-O single-bond vibration. [4] High confidence
2 · 1738 1.00 - - - -
3 · 1124 0.83 - - - -
4 ★ 1186 0.77 Literature-supported assignment The band at 1186 cm-1 is assigned to C-O single-bond vibration. [5] High confidence
5 · 1042 0.61 - - - -
6 · 1452 0.21 - - - -
7 ★ 1267 0.17 Literature-supported assignment The band at 1267 cm-1 is assigned to C-O single-bond vibration. [1] Moderate confidence
8 · 941 0.14 - - - -
9 · 753 0.13 - - - -
10 · 866 0.12 - - - -
11 ★ 1381 0.10 Literature-supported assignment The band at 1381 cm-1 is assigned to methyl group vibration. [6] Moderate confidence
12 ★ 2988 0.09 Literature-supported assignment The band at 2988 cm-1 is assigned to methyl group vibration. [2] High confidence
13 · 690 0.07 - - - -
14 ★ 3501 0.05 Literature-supported assignment The band at 3501 cm-1 is assigned to free alcohol O-H. [7] Moderate confidence
Literature

References

No. Title DOI Page
[1] Zhang 等 - 2020 - Enhanced heavy metal removal from an aqueous envir 10.1038/s41598-020-73570-7 -
[2] Li 等 - 2020 - Effect of molecular weight of polyethylene glycol 10.1039/d0ra08699a -
[3] Groat 等 - 2009 - The crystal chemistry of holtite 10.1180/minmag.2009.073.6.1033 14
[4] Aziz 等 - 2019 - Development of Polymer Blend Electrolyte Membranes 10.3390/ijms20133369 4
[5] Muljana 等 - 2022 - Cross-Linking of Polypropylene via the Diels-Alder 10.3390/polym14061176 7
[6] Maeda - 2001 - IR spectroscopic study on the hydration and the ph 10.1021/la001346q 3
[7] Popa 等 - 2022 - Influence of Convective and Vacuum-Type Drying on 10.3390/molecules27134063 10
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Appendix

Sample information and raw spectrum

Original uploaded spectrum for reference and verification.

Baseline correction method: Asymmetric Least Squares Smoothing

The wavelength range for analysis(cm-1): [(400, 4000)]

Raw spectrum without baseline correction or other processing:

Sample spectrum image
Discussion

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