PVAc, pyrolysis

Direct insertion probe pyrolysis mass spectrometry (DPMS) utilises a device for introducing a single sample of a solid or liquid, usually contained in a quartz or other non-reactive sample holder, into a mass spectrometer ion source. A direct insertion probe consists of a shaft having a sample holder at one end [70] the probe is inserted through a vacuum lock to place the sample holder near to the ion source of the mass spectrometer. The sample is vaporized by heat from the ion source or by heat from a separate heater that surrounds the sample holder. Sample molecules are evaporated into the ion source where they are then ionized as gas-phase molecules. In a recent study, Uyar et al. [74] used such a device for studying the thermal stability of coalesced polymers of polycarbonate, PMMA and polylvinyl acetate) (PVAc) [75] and their binary and ternary blends [74] obtained from their preparation as inclusion compounds in cyclodextrins. 

Figure 12.11 shows the pyrograms of vinyl paints from two monochromes by the Italian artist Piero Manzoni. The two paints are clearly different in composition acetic acid (peak 1) and benzene (peak 2) are present as common markers of the PVAc binder in both cases, but sample (a) contains dibutyl phthalate (peak 6) as external plasticizer. Peak 5 was recognized as bis(2-methylpropyl)-phthalate which is formed from dibutylphthalate isomerization, while butyl acetate (peak 3) and butyl benzoate (peak 4) are secondary products of recombination reactions occurring during the pyrolysis. Sample (b), however,... 

PTV PU PVA PVAC PVAL PVC PVDC PVDF PVE PVF PXRD py Py PY Py-GC-MS pyr pyrr pz programmed-temperature vaporizer polyurethane poly (vinyl alcohol) poly(vinyl acetate) poly (vinyl alcohol) poly (vinyl chloride) poly(vinylidene dichloride) poly(vinylidene difluoride) poly (vinyl ether) poly(vinyl fluoride) powder X-ray diffraction pyridine (ligand) pyridine pyramidal (coordination compounds) pyrolysis-gas chromatography-mass spectrometry pyrazine (ligand) pyrrolidine (ligand) pyrazole (ligand)... 

Direct insertion probe mass spectrometry (DIP-MAS) analyses of poly(methyl methacrylate) (PMMA), poly(vinyl acetate) (PVAc), and their coalesced and precipitated blends were performed [51] (see Fig. 21). The fact that the pyrolysis mass... 

Fig. 21 Evolution profiles of some characteristic products recorded during the pyrolysis of the coalesced (left) and solution-cast (right) PMMA/PVAc blends...

Table 3 The assignments and intensities (relative to the weakest peak) of the characteristic and intense peaks in the pyrolysis mass spectra of physical and coalesced PMMA/PVAc blends at temperatures corresponding to maxima in the TIC curves (Fig. 21) [51]...

The TIC curve recorded during the pyrolysis of PVAc shows two peaks indicating a two-step thermal degradation mechanism (Figure 46.20). The mass spectra recorded at 359 and 456 C and the trends in the singleion evolution profiles suggest the first step to be the loss of side chains and evolution of acetic acid, and the second step to be the decomposition of the unsaturated polymer backbone generated. 

FIGURE 46.20 (A) TIC curve recorded during pyrolysis of PVAc. (B) The mass spectrum recorded at the peak maximum at 359 and 456°C and (C) single ion evolution profiles of C2H3O, VAc, C7H7, and C24H27. 

PC/PVAc At 300°C deacetylation of PVAc accelerates degradation of PC well above that of neat polymer Immiscible blends TGA, pyrolysis + MS to 650°C 173... 

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