General Note
Infrared and Raman spectroscopy are complementary techniques allowing to
detect absorption due to vibration energies in organic molecules.
4.4 Analyses of Macromolecular Matter: Pyrolysis
and Chemical Degradation
Outlook
Macromolecular substances need special approaches for identification and
quantification. As a principal strategy, two procedures break down the polymers in order to identify the low molecular products. Analytical pyrolysis as
well as chemical degradation procedures used for polymer analyses are
described in this chapter.
The analysis of macromolecular substances needs some special considerations.
Polymers are not volatile, consist of molecular repetition units in regular or irregular
order and exhibit not only one defined weight but a molecular weight distribution.
All these properties prevent a reasonable direct analysis by GC/MS or LC/MS,
whereas spectroscopic analyses only reveal bulk information about the molecular
composition. Different analytical approaches have been developed to overcome
these adversities. As a principal idea, two approaches convert the macromolecular
substances at first into low molecular fragments for further analyzing by standard
procedures such as GC/MS. Fragmentation can be initiated by pyrolysis or chemical
degradation. As a final step, the obtained information about the molecular fragments
need to be assessed for reconstruction of the original polymer. Noteworthy, these
approaches work for geo- and biopolymers as well as for synthetic polymers.
4.4.1 Analytical Pyrolysis
High temperatures with absence of oxygen break down macromolecular substances
in a semi-regular way. Depending on the molecular structure of the polymer,
pyrolysis produces a wide range of products from a few up to hundreds of fragments.
Noteworthy, the overall pyrolysis yield of detectable compounds is commonly in the
lower percentage level. As a principle approach, structure specific pyrolysis products
need to be identified for both identification and quantification.
This can be illustrated best for synthetic polymers. In Fig. 4.51 indicative
pyrolysis products are illustrated pointing more or less accurate to the original
polymer structures of polyacrylamides, polyethylene or polystyrene. Similar
88
4 Instrumental Analysis
Infrared and Raman spectroscopy are complementary techniques allowing to
detect absorption due to vibration energies in organic molecules.
4.4 Analyses of Macromolecular Matter: Pyrolysis
and Chemical Degradation
Outlook
Macromolecular substances need special approaches for identification and
quantification. As a principal strategy, two procedures break down the polymers in order to identify the low molecular products. Analytical pyrolysis as
well as chemical degradation procedures used for polymer analyses are
described in this chapter.
The analysis of macromolecular substances needs some special considerations.
Polymers are not volatile, consist of molecular repetition units in regular or irregular
order and exhibit not only one defined weight but a molecular weight distribution.
All these properties prevent a reasonable direct analysis by GC/MS or LC/MS,
whereas spectroscopic analyses only reveal bulk information about the molecular
composition. Different analytical approaches have been developed to overcome
these adversities. As a principal idea, two approaches convert the macromolecular
substances at first into low molecular fragments for further analyzing by standard
procedures such as GC/MS. Fragmentation can be initiated by pyrolysis or chemical
degradation. As a final step, the obtained information about the molecular fragments
need to be assessed for reconstruction of the original polymer. Noteworthy, these
approaches work for geo- and biopolymers as well as for synthetic polymers.
4.4.1 Analytical Pyrolysis
High temperatures with absence of oxygen break down macromolecular substances
in a semi-regular way. Depending on the molecular structure of the polymer,
pyrolysis produces a wide range of products from a few up to hundreds of fragments.
Noteworthy, the overall pyrolysis yield of detectable compounds is commonly in the
lower percentage level. As a principle approach, structure specific pyrolysis products
need to be identified for both identification and quantification.
This can be illustrated best for synthetic polymers. In Fig. 4.51 indicative
pyrolysis products are illustrated pointing more or less accurate to the original
polymer structures of polyacrylamides, polyethylene or polystyrene. Similar
88
4 Instrumental Analysis