Raman spectroscopy: The easy way to analyze polymers

Plastics can be divisive since they are convenient and inexpensive, yet have a harmful impact on the environment. These materials are found everywhere – from museums to modern medicine, and even in the ocean waves. Plastic is ubiquitous, and Raman spectroscopy can be used anywhere it is located for identification, classification, and quality testing purposes.

Raman spectroscopy for polymer analysis

Raman spectroscopy is increasingly chosen for polymer analysis because it is non-destructive, requires no sample preparation, and gives results in just seconds. It is easy on the user; even non-technical operators can collect data on-site. Raman is also environmentally friendly – requiring no chemicals, solvents, or materials for sample prep – and it does not generate any waste.
 

Learn more about the fundamentals of Raman spectroscopy in our blog article. 

FAQ about Raman spectroscopy: Theory and usage

Raman spectroscopy has many fundamental qualities that surpass other techniques for polymer analysis. These include: high material specificity, large libraries of known substances and mixtures, and the ability to sample plastics in myriad forms including clear and colored composites, coatings, and adhesives. Such accuracy and flexibility is key for the precise characterization of plastic materials and mixtures; any deviation from a standard polymer mixture can change its physical properties and color. 

What makes Raman spectroscopy unique?

Few spectroscopic techniques meet the need for fast, easy, accurate, non-destructive, and flexible testing: near-infrared (NIR) and Raman spectroscopy top this list. These techniques qualify and quantify different polymers for research, analysis, and quality control purposes.

How Raman spectroscopy can impact the polymer industry

The global movement toward 100% testing of incoming goods and quality checks down the production line requires efficient and low-resource methods. Raman’s capabilities make it an ideal quality control (QC) technique. With Raman, manufacturers can quickly check raw materials at the point of receipt before they enter production and avoid costs associated with long laboratory wait times, production interruptions, and training of technical personnel. Among the highest recommendations for Raman are its simplicity and ease of use for the operator. One does not have to be a trained spectroscopist to use Raman!

Knowing the exact composition of raw materials and resin blends allows manufacturers to control and optimize polymerization processes and make more consistent products that best meet customer specifications. 

For example, raw polymer materials often appear as white or black pellets, but it can be difficult to identify their composition just by looking at them. Precursors to Metrohm’s current Raman devices were used to build a Raman library of spectra based on a set of polymer references from the ResinKit Company, located in Woonsocket, RI (USA). This library was used by a global maker of artificial joints at every step of the production process. While it is impossible to discriminate between polyamide and polycarbonate visually, it is essential to distinguish each of them because different resin mixtures influence the performance and longevity of the finished product.
 

For more information about using Raman spectroscopy to identify and characterize polymers, read our Application Note.

The Benefits of Raman Spectroscopy for the Identification and Characterization of Polymers

Raman polymer analysis applications

Summary

Not only is Raman spectroscopy a fast analytical technique, it is also non-destructive, environmentally friendly, and easy to use. Handheld and portable Raman instruments help this technology to become widely adopted even in nontraditional locations. The use of Raman for the analysis of various polymers is a great example of how technology can help us read the world—from the sea to QC!

References

[1] Neves, A.; Friedel, R.; Melo, M. J.; et al. Best Billiard Ball in the 19th Century: Composite Materials Made of Celluloid and Bone as Substitutes for Ivory. PNAS Nexus 2023, 2 (11), pgad360. DOI:10.1093/pnasnexus/pgad360

[2] Neves, A.; Friedel, R.; Callapez, M. E.; et al. Safeguarding Our Dentistry Heritage: A Study of the History and Conservation of Nineteenth–Twentieth Century Dentures. Heritage Science 2023, 11 (1), 142. DOI:10.1186/s40494-023-00989-2

[3] Bruno. A device used by the scientific police to study the nature of plastics collected at sea. Expédition MED. https://www.expedition-med.org/actualites/un-appareil-utilise-par-la-police-scientifique-pour-etudier-la-nature-des-plastiques-preleves-en-mer/ (accessed 2024-08-08).

[4] emmao. The Recycling Conundrum. Plastic Free Communities, 2024.

Your knowledge take-aways

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Application Note: Identification of microplastics with Raman microscopy

Application Note: The Benefits of Raman Spectroscopy for the Identification and Characterization of Polymers