Acrylonitrile-butadiene rubber (NBR) is widely used across industries because of its excellent oil resistance, durability, and mechanical strength. These properties are often enhanced using various additives. To fully understand the chemical composition and behavior of NBR during thermal degradation, precise analytical techniques are required.
In this technical note, Evolved Gas Analysis-Mass Spectrometry (EGA-MS) is used as a fundamental investigation method in Pyrolysis GC/MS to determine the pyrolysis temperature and identify the chemical species released at different temperature zones.
Understanding NBR and the Need for EGA-MS
NBR contains a mix of main polymer components and multiple additives that influence:
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Weather resistance
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Mechanical performance
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Stability under heat
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Overall material quality
Because of this complex formulation, analyzing both the polymer and additives is essential for quality control and material characterization.
EGA-MS provides a temperature-resolved profile of compounds released during controlled heating—delivering a clear chemical fingerprint of the material.
Background: Acrylonitrile-butadiene rubber (NBR) is a synthetic rubber which has excellent properties such as high oil resistance and wear resistance. It contains various additives to improve weather resistance, mechanical properties, etc.
Therefore, not only main components of the NBR material but also additives need to be analyzed to assess the polymer properties. In this note, Evolved Gas Analysis (EGA)-MS is conducted as the fundamental investigation for the compositional analysis of NBR by pyrolysis GC/MS to determine the pyrolysis temperature. In addition, chemical species were surveyed from the averaged mass spectrum of each temperature zone of EGA curves.
Experimental: A GC/MS system with a Multi-Shot Pyrolyzer (EGA/PY-3030D) directly interfaced to the GC injector was used for EGA-MS measurements. A deactivated metal tube (UADTM-2.5N) and a Vent-free GC/MS adapter were installed between the GC injector and the mass detector. Two types of NBRs with varied compounding ratios were used as samples.
The NBR samples were scraped off with a cutting knife, and then the scraped pieces were put into an Eco-Cup, precisely weighed (ca. 0.1 mg each), and introduced into the pyrolyzer furnace for EGA-MS measurements.
Results: EGA curves and averaged mass spectra of the NBR samples are shown in Fig. 1. Additives should mainly appear in the lower temperature zone, i.e. Zones 1-A and 2-A. Peaks detected in Zones 1-B and 2-B are derived from the pyrolysis of NBR. It is confirmed that the polymer type is both NBR based on the library search of the averaged mass spectra using the F-Search. For both NBR samples, evolution of gases from the polymer component was completed by 600 ºC. Thus, pyrolysis temperature in Py-GC/MS was determined to be 600 ºC. In the next note (PYA1-173E), the qualitative analysis of polymer and additives in NBR samples was conducted by Py-GC/MS. Further, the quantitative analysis of monomer composition (compositional ratio of acrylonitrile to butadiene) was carried out.
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References: This technical note was developed by Frontier Laboratories Ltd. 4-16-20 Saikon, Koriyama, Fukushima, 963-8862 JAPAN. www.frontier-lab.com