Materials Identification

"What is it?" This is one of the commonly asked questions. Sometimes, a manufacturer wants to get assurance that a purchased raw material is correct. In other cases, a comparison with a competitor material is needed. There are times when material that is being sourced from a global partner must be tested for quality assurance purposes.

Plastic, rubber, polymer and even metals are tested using spectroscopy methods to provide confident identifications. Four of the heavily used spectroscopic methods are featured in this newsletter.

Infrared Spectroscopy

Infrared spectroscopy is the workhorse of the materials identification laboratory. Modern instruments are Fourier transform infrared spectrometers (FTIR). FTIR spectrometers have very high signal-to-noise ratios. Highly descriptive interpretable information can be obtained, nondestructively, from samples that are smaller than the period at the end of this sentence.

FTIR spectroscopy provides a spectrum, often referred to as a chemical "fingerprint" of materials. It is common for the FTIR spectroscopy system to have computer-based spectral libraries containing tens of thousands of reference spectra. These commercially available spectral libraries, together with custom libraries developed within the laboratory, allow for powerful identification of polymers, plastic, and rubber materials.

In our laboratory the most common applications for the FTIR spectroscopic method are for projects involving;

• Comparison of Materials From Different Suppliers
• Baseline Data for Failure Analysis Investigations
• Deformulation Analysis
• Critical Data for Legal Cases
• Comparison of "Good" and "Bad" Materials

Nuclear Magnetic Resonance Spectroscopy

While FTIR spectroscopy is an excellent method for determining the identification of polymer, plastic, and rubber materials it is sometimes also important to describe the polymer molecules in greater detail. To aid in the identification of polymers, and to get information about the specific arrangement of the molecule repeat units that comprise a polymer, nuclear magnetic resonance (NMR) spectroscopy is employed.

In our laboratory the most common applications for the NMR spectroscopic method are for projects involving;

• Polymer Identification
• Comparison of "Good" and "Bad" Materials
• End Group Analysis
• Side Chain Length Distribution Analysis
• Copolymer and Blend Ratio Determination

Inductively Coupled Plasma Spectroscopy

In addition to analyzing polymer, plastic, and rubber materials it is also important to analyze metals and inorganic materials. Sometimes the chemical elements that comprise a metal are quantitatively determined to identify a specific metal or alloy. In other cases it is important to assure that products do not contain toxic, banned, or regulated substances. To be RoHS (Restriction of Hazardous Substances) Directive compliant, six banned substances: lead, mercury, cadmium, hexavalent chromium, poly-brominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE), must not be present in quantities exceeding the maximum allowed concentration values.

Inductively coupled plasma (ICP) spectroscopy is an appropriate analytical method for determining the chemical elements that comprise a sample. The spectrum that is obtained from a dissolved or digested sample, with proper calibrations, indicates the concentration of chemical elements. The ICP spectroscopy method can be used to determine the concentration of lead in children´s toys or jewelry, the composition of an aerospace alloy, the constituents of a polymer additive package, or the composition of particulate contaminants harvested from filters or excised from products.



In our laboratory the most common applications for the ICP spectroscopic method are for projects involving;

• Children's Toys and Childcare Products (CPSIA Section 108)
• Residual Catalyst Levels
• Imported Goods Testing
• Metal Contamination in Medical, Pharmaceutical, Biologics, and Molded Products
• Compliance Testing (RoHS, CPSC)

We bring you chemical analysis information that answers the question; "What is it?" You can get definite identification and comparisons of competitor products with yours, verification of materials supplied by global partners, and information to support failure analysis investigations using spectroscopic methods. Our experts routinely use two highly reliable, information-rich methods for plastic and rubber analysis: Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. For the analysis of metal samples we use inductively coupled plasma (ICP spectroscopy) and energy dispersive spectroscopy (EDS).

So, browse through this e-Newsletter for information about;

• Fourier Transform Infrared Spectroscopy (FTIR)
• Nuclear Magnetic Resonance Spectroscopy (NMR)
• Inductively Coupled Plasma (ICP) Spectroscopy
• Energy Dispersive Spectroscopy (EDS)

Of course, we also have the two ever-popular e-Newsletter sections;

• Jay´s Cool Microscopy Pics of the Month

• Cool Chemistry Links

Energy dispersive spectroscopy (EDS) is usually applied to a sample while the specimen is being evaluated with the scanning electron microscopy (SEM) method of analysis. The SEM provides a wide range of magnifications at superb depth of field. The images obtained with the SEM can cover the low magnification range of an optical microscope and then extend up to several thousand times magnifications.



The SEM images provide detailed information about the size, shape, and surface textures of the specimen. Coupled with the SEM image, one can obtain the chemical elemental information for that same region from which SEM images were obtained. The EDS spectrum reveals the specific elements and also their approximate concentrations.

Of additional use is the ability to produce elemental maps that indicate the relative concentration of every chemical element over the same region from which the SEM image was acquired. So, for example, the residue from a filter can be evaluated with respect to the size and shape of captured particles and the EDS method can ascribe chemical composition information to each type of particle.



In our laboratory the most common applications for the EDS spectroscopic method are for projects involving;

• Contamination Analysis
• Materials Identification
• Compliance Testing (RoHS, CPSC)
• Imported Good Testing
• Paint Coatings Analysis