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, is the founder and CEO of Big Sur Scientific, a maker of portable mid-infrared cannabis analyzers. He has over 30 years experience as an industrial infrared spectroscopist, has published numerous peer-reviewed papers, and has written three books on spectroscopy. As a trainer, he has helped thousands of people around the world improve their infrared analyses. In addition to writing for Spectroscopy, Dr. Smith writes a regular column for its sister publication Cannabis Science and Technology and sits on its editorial board. He earned his PhD in physical chemistry from Dartmouth College.

Articles

Epoxies are perhaps the most economically important functional group of polymers. We explain how to interpret their spectra.

The Infrared Spectra of Polymers V: Epoxies

Many rubbery polymers contain C=C bonds, which means they are alkenes. Thus, we can identify natural and synthetic rubbers by examining the spectra of cis-, trans-, and tri-substituted alkenes.

The Infrared Spectra of Polymers IV: Rubbers

Here, we finish a discussion of the spectrum of polyethylene (PE) and explore
how different PE syntheses produce materials with different physical and
spectroscopic properties.

The Infrared Spectra of  Polymers II: Polyethylene

Naoto Nagai, of the Industrial Research Institute of Niigata Prefecture in Japan, has been studying the potential of IR spectroscopy for investigating higher-order structures of polymers. He and his colleagues recently looked at the IR spectra of polyoxymethylene (POM) mold plates and the cause of occasional resin cracks.

Solving Polymer Problems Using IR Spectroscopy

The in situ combination of rheometry and Raman spectroscopy allows for real-time, synchronized measurement of both physical and chemical material properties.

Monitoring Polymer Phase Transitions by Combining Rheology and Raman Spectroscopy

Polymer laminates typically make complex samples for infrared analysis, comprising multiple layers with defined thicknesses, in some cases less than 10 µm. When measuring extremely narrow laminate layers, the use of attenuated total reflectance (ATR) may provide improved spectra of the laminate cross-section, because ATR microscope objectives offer a greater spatial resolution than transmission due to additional magnification. This paper details the preparation of polymer laminate sample cross-sections and the collection of transmission and ATR spectra of various layers. Further analysis of the laminate spectra will also be explored utilizing a multivariate curve resolution (MCR) algorithm. An example laminate sample is examined utilizing all the tools available on a standard FT-IR microscope.

FT-IR Microscopic Analysis of Polymer Laminate Samples Including Transmission and ATR Spectroscopy

Christian Pellerin, a professor in the Department of Chemistry at the University of Montreal in Canada, is using Raman spectroscopy and the most probable distribution method to quantify the orientation of polymers and electrospun fibers. Spectroscopy recently spoke with him about this work.

New Methods in Raman Spectroscopy Advance the Analysis of Polymers and Electrospun Fibers

The mechanical properties of polymer films such as tensile strength and resistance to tearing depend strongly on the orientation of the polymer chains. Fourier transform infrared (FT-IR) spectroscopy can be used to measure the degree of orientation both within the plane of the film and normal to it.

Measuring Orientation in Polymer Films

A new method allows samples to be measured "as-is" with direct contact with the ATR crystal.

Sample Preparation–Free Micro ATR FT -IR Chemical Imaging of Polymers and Polymer Laminates

Infrared reflection spectroscopy is a tool that can be used to study coated plastics, but the spectra can show unexpected features. In this report, we calculate the specular reflectance for a flat surface of two different polymers as well as how their spectra change when the other polymer is added as a film with a thickness of up to 2.5 ?m. One of the unusual phenomena we observe is that "derivative"-shaped substrate bands invert in sign as the other polymer is added as a coating. We also show how the reflection of the surface changes and becomes polarized as the angle of incidence increases.

Plastics Polymers and Rubber