Page 446 - Handbook of Materials Failure Analysis

444 CHAPTER 17 Application of pyrolysis

separated substances are then detected with mass spectrometer (MS) (Figure 17.1),
and subsequently identified by interpretation of the obtained mass spectra or by
using mass spectral libraries (e.g., NIST/EPA/NIH, Wiley, MPW, or Norman Mass
Bank). The detection technique of the separated compounds is typically MS, but
other gas chromatographic detectors have been also used depending on the inten-
tions of the analysis. The analytical Py-GC/MS allows the direct analysis of very
small solid or liquid polymer/copolymer sample amounts (5-200 μg), without the
need of time-consuming sample preparation (sample pretreatment). The identifica-
tion of complex mixtures or blends as well as identification of samples with so-
called difficult matrices is also possible in many cases. Due to these small sample
amounts, the investigation of heterogeneous polymers with a coarse phase or a gra-
dient composition structure (phase separation, poor mixing, etc.) is sophisticated
and may lead to great variations in the measuring results. In this case, a multiple
determination of different positions of the investigated part is essential to achieve a
significant image of its composition.
The applications of the analytical Py-GC/MS range from research and develop-
ment of new materials, quality control, characterization and competitor product eval-
uation, medicine, biology and biotechnology, geology, airspace, environmental
analysis to forensic purposes or conservation and restoration of cultural heritage.
These applications cover analysis and identification of polymers/copolymers and
additives in components of automobiles, tires, packaging materials, textile fibers,
coatings, adhesives, half-finished products for electronics, paints or varnishes,
lacquers, leather, paper or wood products, food, pharmaceuticals, surfactants, and
fragrances [2–5].
For more than 10 years, our laboratory has been involved in projects from the
area of failure analysis in the automotive, chemical, or rubber industry by using the
analytical Py-GC/MS. The practical application of these analytical techniques
ranges from case studies of automotive components failure analysis of failed
hydraulic cylinders, membranes, as well as the packaging of hydraulic cylinders,
sealing rings, tire materials and additives, auto paints, auto wrapping foils, auto
catalysts, mineral oils, and brake fluids. Further applications include identification
of plastic particles from industrial filter fins, residues of fittings of refrigerant com-
pressors, residues from a valve block of a medical respirator, identification of den-
tal filling materials, detection of counterfeits of plastic and rubber products,
modules from building industry, fouling from a roller bearing, adhesives, sealing
compounds, cesspit residues from an extruder or polyethylene regranulate from
mechanical recycling process, or polymer residues in recycled aluminum. The
obtained analytical results are then used for troubleshooting and remedial action
of the technological process.
Here, we report on application examples of the analytical Py-GC/MS and the
SEM in failure analysis of chemical materials such as motor vehicle brake fluids,
varnishes, and rubber materials of car tires. Furthermore, failure cases demanding
identification of polymers/copolymers in paint on the surface of a rubber membrane
from the pressure vessel of an automotive integral accumulator and identification of