Polyethylene terephthalate, decomposition

Direct evidence of nucleation during the induction period will also solve a recent argument within the field of polymer science as to whether the mechanism of the induction of polymers is related to the nucleation process or to the phase separation process (including spinodal decomposition). The latter was proposed by Imai et al. based on SAXS observation of so-called cold crystallization from the quenched glass (amorphous state) of polyethylene terephthalate) (PET) [19]. They supposed that the latter mechanism could be expanded to the usual melt crystallization, but there is no experimental support for the supposition. Our results will confirm that the nucleation mechanism is correct, in the case of melt crystallization. 

M. Day and D. M. Wiles, Influence of temperatnre and environment on the thermal decomposition of polyethylene terephthalate fibres, with and withont the flame retardant tri(2,3)-dibromopropyl phosphate., J. Anal Appl J rolysis, 7, 65-82, (1984). 

Polyethylene terephthalate (PET). At temperatnres above 300°C PET pyrolysis proceeds via a random-chain scission of the ester links to yield a mixture of terephthalic acid monomer and vinyl ester oligomers [47], The presence in the monomer of oxygen and a benzene ring imphes that the decomposition prodncts contain aromatic and oxygenated carbon componnds, like CO2, ketones and aldehydes [27],... 

The thermal degradation of PE mixed with polyethylene terephthalate (PET) and PE only degradation were compared. The presence of small amounts of PET is quite possible with the mixture of PE, PP, and PS, which is generally considered as municipal waste plastics. The yields of product gases, liquids and residues from the degradation of PET and the mixtures of PET and PE in ratios of 1 9 and 2 8 are shown in Table 18.4. Unlike PE or PVC, no liquid products could be obtained from the degradation of PET. The decomposition of PET proceeds with the production of a large amount of pale yellow... 

In a previous paper (1), phase segregation by spinodal decomposition in mixtures of polyethylene terephthalate and polyhydroxybenzoic acid copolymer (PET-PHB) and polycarbonate (PC) has been investigated. It was shown that thermally induced phase segregation takes place above the Tg of PC and exhibits a lower critical solution temperature (LCST). However, the phase separated domains do not grow until the temperature exceeds 255°C. Some disclinations developed within the liquid crystal rich regions. Even in the pure PET-PHB component, four dark brushes with negative sense of disclinations form around 240°C, indicating the presence of nematic liquid crystals. Paci and coworkers (2) claimed that a smectic-nematic transition exists near 270°C in this liquid crystalline copolyester. 

Chiu (116) used the apparatus previously described to study the thermal decomposition of selected polymers such as polyethylene terephthalate), po y(vinyl fluoride), po y(vinylidene fluoride), and others. The dielectric constant curves of a group of fluorocarbon polymers are shown in Figure 11.33. As illustrated, the more polar polymers such as poly(vinylidinefiuoride) (PVDF) and poly(vinyl fluoride) (PVF) show characteristic dielectric loss peaks that are distinguishable from the relatively featureless and low-loss curves of the other polymers. For PVF, the low-temperature process is due... 

Second, a molecule or molecular fragment can also be split which is called decomposition. To recycle bottles made of polyethylene terephthalate (PET) catalytic depolymerization is used to split the PET in valuable components. ... 

Polyethylene terephthalate (PET) is a typical representative of comparatively thermally resistant aryl aliphatic polyesters its thermal decomposition begins at temperatures... 

T. Suebsaeng and C. A. Wilkie, SoUd products from thermal decomposition of polyethylene terephthalate Investigation by CP/MAS13C-NMR and Eourier transform-lR spectroscopy. Journal of Polymer Science Polymer Chemistry Edition, 22,945 (1984). 

Various SCFs, other than SCW, have been examined for the treatment of organic wastes and chlorinated hydrocarbons, and some of them have been commercially used. Supercritical methanol is often used, instead of SCW, under the conditions of t = 240-300°C and p = 8-15 MPa for selective decomposition or methylation of organic materials. One example is the recycle of polyethylene terephthalate (PET) bottles decomposing to its monomers by supercritical methanol [7]. 

Another method for avoiding losses of metals during ashing is the low-temperature controlled decomposition technique using active oxygen. This method has been studied in connection with the determination of trace metals in polyvinyl chloride (PVC), polypropylene (PP), and polyethylene terephthalate [29]. 

K. Stoeffler, P. G. Lafleur, and J. Denault, Thermal decomposition of various alkyl onium organoclays Effect on polyethylene terephthalate nanocomposites properties. Polymer Degradation and Stability, 93 (2008), 1332-50. 

It is somewhat arbitrary to select the compliances rather than the moduli for decomposition, without more knowledge of the origin of the viscoelasticity. In fact, a similar analysis on the basis of the moduli E and E" has been performed on data for crystalline polyethylene terephthalate by Kawai and associates. The two procedures correspond to assuming that the stress or the strain, respectively, is homogeneous throughout the sample. Actually, depending on the structure and microscopic features of the viscoelastic response, neither may be strictly homogeneous cf. Chapter 14, Section F). 

In the case of polymer/clay nanocomposites, alkylammonium exchange species influence the affinity between the polymer and the clay surface. For example, it was reported that clays treated with dialkyl dimethylammonium halides, in particular with two chains of about 18 carbon atoms, have a surface energy similar to poly(olefins) such as polypropylene (PP) and polyethylene (PE) [27]. Polar polymers as polyamides (PA) have been recommended to get better interactions as reported by Toyota [8]. The alkyl chain length is related with increase in interlayer space required for the intercalation of polymer chains. Because of the nonpolar nature of their chains, they reduce the electrostatic interactions between the silicate layers and lower the surface energy of the layered silicates. As a consequence, an optimal diffusion of the polymer to dissociate the stacked clay layers, that is, an exfoliation process, can be obtained. Despite the compatibility of MMT modified by long alkyl chain quaternary ammonium with hydrophobic polymers (PE and PP), conventional alkylammonium ions show low thermal stability, that is, an onset decomposition temperature is close to 180°C.This poor thermal stability could limit their use in the preparation of PLS with matrices processed at high temperatures such as PA, poly(ethylene terephthalate) (PET), and poly(ether ether ketone) (PEEK) [30]. 

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