Polymer degradation product alkyl

Figure 11.5 shows that the functional group compositional analysis of the pyrolysis oil/waxes derived from the fixed-bed pyrolysis of PVC, PS and PET is very different from the polyalkene plastic pyrolysis oil/waxes. The spectra of the PVC pyrolysis oil/wax shows that the characteristic peaks of alkanes and alkenes are present as described for the polyalkene plastics. Since the PVC plastic polymer is based on a similar backbone structure to the polyalkene plastics, a similar degradation product oil/wax composition may be expected. However, the spectra for PVC in Figure 11.5 show that there are additional peaks in the region of 675-900 cm and 1575-1625 cm The presence of these peaks indicates the presence of mono-aromatic, polycyclic aromatic and substituted aromatic groups. Benzene has been identified as a major constituent in oils derived from the pyrolysis of PVC whilst other aromatic compounds identified included alkylated benzenes and naphthalene and other polycyclic aromatic hydrocarbons [19, 32, 39]... 

Monomers, dimers and higher-molecular-weight oligomers are the predominant decomposition products of the lower alkyl polymers. The major degradation products of higher alkyl polyacrylates are olefins, alcohols and acrylate monomers (see Table 5), which are different from those of the lower alkyl polyacrylates. 

The characteristic features of the degradation of alkyl methacrylate polymers are considered elsewhere (see Section 15.3.2). In contrast to PEMA, PFEMA gives no monomer. In addition to the ester decomposition products vinyl fluoride and CO2, acetaldehyde and fluoroacetaldehyde are produced. Explanations have been proposed for the latter products on the basis of meth-acrylic acid/FEMA and FEMA/radical end FEMA adjacent unit interactions. It is argued that the ester decomposition route is favoured by F atom activation of the hydrogens, so suppressing depolymerization. 

Thermal degradation of Irganox 1076 in air was studied by means of HPLC-UV/VIS and by preparative HPLC-NMR. At 180 °C cinnamate and dimeric oxidation products are formed, and at 250 °C de-alkylation products are observed [660], On-line LC-NMR hardly covers a real need in polymer/additive analysis, as the off-line option is mostly perfectly adequate for that purpose. 

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