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Contribution to the
Characterization, Identification
and Comparison of Polyurethane
Foam Particles
Skip Palenik
Mark Palenik
Microtrace LLC
Elgin, IL USA
www.microtracescientific.com

Particles of plastic foam are occasionally
encountered during the examination of
microscopic trace evidence

The fact that they are usually observed as small
particles (and thus easily transferable) is typically an
indication that the source object has degraded

In cases where the source can be determined these
particles can provide significant evidence of contact

Microscopical and microchemical methods
are complimentary and have both proven of
value in this type of analysis

• Stereomicroscopy
Microscopy
• Polarized light microscopy
• Phase contrast microscopy
• Color/MSP
• Fluorescence/MSF
• SEM-EDS / Micro-XRF

Stereomicroscopy
Shape
Color

Some details of internal structure can often
be observed even before mounting for PLM

Testing for elastomerism

Polarized light microscopy
(Mounted in 1.660)

Birefringence

Phase contrast microscopy

Microspectrophotometry

Raman microspectroscopy
PB 15 Raman reference spectrum
Blue foam Raman spectrum

Fluorescence microscopy and
Microfluorimetry

SEM-EDS Analysis

SEM-EDS Analysis

Micro-XRF spectrum showing
bromine from flame retardant

Microchemical Methods –
primarily instrumental
• Infrared microspectroscopy as neat
particle in compression cell (if
necessary)
• Infrared microspectroscopy after
solvent extraction
• Raman microspectroscopy
• GC/MS
• Solvent extraction
• Pyrolysis

Micro-FTIR
• Identify as polyurethane or other.
• Classify as polyether or polyester.
• After extraction identify plasticizers
(e.g. phthalates) and obtain
spectrum of the neat polyurethane
• Compare infrared spectra

Polyester type urethane - neat

Polyester urethane after acetone wash

Acetone extract from Foam 2

Polyether type urethane foam - neat

Polyether urethane after acetone wash

Acetone extract from foam 4

GC-MS
• Information from both extraction and
pyrolysis. Extraction provides
especially useful data on lower
molecular weight compounds.
• Separation and identification of
ingredients of the product (e.g.
plasticizers, styrene, etc.)
• Study of breakdown products, which
provide especially good points of
comparison.

kCounts Sample ID: Sample #1
700
Pyrolysis
600
Benzene, 2,4-diisocyanato-1-methyl-
500
2H-Benzimidazol-2-one, 1,3-dihydro-5-methyl-
400
300
Indole-2-one, 2,3-dihydro-6-amino-
Benzene, 1,3-diisocyanato-2-methyl-
200
100
0
2.5 5.0 7.5 10.0 12.5 15.0 17.5
minutes

MCounts Sample ID Sample 1
Acetone extract
Indole-2-one, 2,3-dihydro-6-amino-
1.5
Benzene, 1,3-diisocyanato-2-methyl-
2H-Benzimidazol-2-one,
1,3-dihydro-5-methyl-
Benzene, 2,4-diisocyanato-1-methyl-
1.0
1,3-Benzenediamine, 2-methyl-
1,3-Benzenediamine, 4-methyl-
0.5
0.0
2.5 5.0 7.5 10.0 12.5 15.0 17.5
minutes

MCounts
Isobutandiol
Sample ID: Sample #2
Pyrolysis
3
2
1
0
2.5 5.0 7.5 10.0 12.5 15.0 17.5
minutes

MCounts Sample ID Sample 2; 2 dgr-PU ac #2 ac - 8-3-2011dgr-PU ac #2 ac -1.SMS
2.0
Acetone extract
1.5
1.0
0.5
polyol
0.0
2.5 5.0 7.5 10.0 12.5 15.0 17.5
minutes

MCounts
styrene
Sample ID: Jeep, Sample #7
Pyrolysis
7
6
5
Naphthalene, 2-bromo-
4
3
2
ethylbenzene
xylenes
alpha-methylbenzene
1
toluene
dimethylquinoline
0
2.5 5.0 7.5 10.0 12.5 15.0 17.5
minutes

Summary
• By means of microscopical and microchemical
techniques, it is possible to analyze and identify
even single small polyurethane particles.
• By careful selection of techniques and their order
of application, it is possible to characterize single
polyuethane foam particles for purposes of
comparison.
• Since these particles are typically degraded to
some degree, GC-MS analysis of neat particles,
their extracts or pyrolyzates provides a
convenient and reliable means of comparison
based on the degree of chemical alteration that
the Q and K samples have undergone.

Thanks and acknowledgement
• Mark Palenik
• Katie White
• Jay Beckert
• Chris Palenik