Polyethylene Oxalate

Ballistreri and co-workers [59] examined the primary thermal decomposition mechanism of this polymer by Py-MS. Several MS techniques were used to identify compounds present in the pyrolysis mixture comparison of electron impact and chemical ionisation spectra, high resolution accurate mass measurements and tandem mass spectroscopy (daughter and parent ion spectra). The results obtained indicate that intramolecular exchange reactions predominate in the primary thermal fragmentation processes yielding cyclic oligomers up to tetramer. No other pyrolysis products were detectable. 

A small amount of the cyclo oligomers shown in Table 3.6 which contained diethylene glycol units known to be present in the polymer chain were detected by Py-MS. 

Reproduced with permission from A. Ballistreri, D. Garrozo, M. Giuffrida, G. Impallomeni and G. Montaudo, Polymer Degradation and Stability, 1988, 21, 311. 1988, Elsevier [59]  

The chemical ionisation mass spectral data indicate that intramolecular exchange reactions predominate in the primary thermal fragmentation process of polyethylene oxalate resulting in the formation of cyclic oligomers. These products are not stable in the electron ionisation (El) mode and are therefore not directly observed in the El mass spectrum. 

In disagreement with previous workers [56-58, 60] the results obtained by Ballisteri and co-workers [59] appear to exclude the formation of other compounds among the primary thermal degradation products. These might derive from the further decomposition of the primary pyrolysis products. The reason why these secondary, or tertiary, decomposition products are not detected in the Py-MS experiments may be due to the shorter timescale of removal of the pyrolysis products from the hot zone, as compared with a TVA experiment. Of course, the high vacuum and the fast detection of the MS lowers the probability of molecular collisions, so that the occurrence of secondary reactions is reduced for TVA. 

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Table 3.6 Cyclic oligomers formed in the thermal degradation of polyethylene oxalate ...

Although not strictly the subject matter of this book, work is briefly reviewed next on the application of non mass spectrometric Py-GC methods in the determination of polymer structure. This information is inclnded in the hope, when necessary, that chemists will be able to adapt these methods by including a mass spectrometric detailed information on polymer structure acrylates [63, 105-107], rubbers [63, 108-110], PVC [63,111-115], aliphatic polyhydrazides [116], polyoxamides [116], polyamides [117], polyether imides [118], methacrylamide [119], aromatic aliphatic polyamides [117], polyurethanes [120], chitin graft poly(2-methyl 2-oxazolone) [121, 122], polyxylyl sulfide [123-126], epoxy resins [127], polyethylene oxalate [128], polytetrafluoroethylene [129], polyvinylidene chloride [129], polyepichlorohydrin, fluorinated ethylene-propylene copolymer [129], polyvinyl fluoride [129], polyvinylidene [129], fluoride [129], SBR copolymer [129] and styrene-isoprene copolymer [130]. 

Polyethylene oxalate - - Cyclic oligomers Study of primary thermal decomposition mechanism [40]... 

OXALIC ACID. [CAS 144-62-7]. Oxalic acid, HOOC-COOH, or ethanedioic acid, mol wt 90.04, is the simplest dicarboxylic acid. It is soluble in water, and acts as a strong acid. This acid does not exist in anhydrous form in nature and is available commercially as a solid dihydrate, O2H2O4-2H2O, mol wt 126.07. The commercial product is packed in polyethylene-lined paper bags or flexible containers. Anhydrous oxalic acid can be efficiently prepared from the dihydrate by azeotropic distillation in a low boiling solvent that can form a water azeotrope, such as benzene and toluene. 

Al, aluminum oxide BA, boric acid C, cellulose CW, Carbowax 4(X) DEAE, diethylaminoethyl DMF, dimethylformamide DMSO, dimethylsulfoxide ECTEOLA, ethanolomine-epichlorhydrin EG, ethylene glycol F, formamide KC, Whatman KC reversed phase plates KG, kieselguhr OA, oxalic acid P, polyamide PEG, polyethylene glycol 4(X) PEI, polyethyleneimine PG, propylene glycol PO, paraffin oil POEG, polyoxyethylene glycol 1000 SG, silica gel SO, silicone oil TD, tetradecane Un, undecane. 

The use of polymers containing oxygen-based functional groups [polyethylene glycol (PEG), poly(methyl methacrylate) (PMMA)] has been studied to synthesize highly crystalline nanomettic LNM. Mechanical activation of hydrated salts in the presence of oxalic acid and the polymer followed by heating at 800 °C for a few... 

Chemically embossed metallocene polyethylene foams are used, for example in a floor covering. A blowing agent azodicarbonamide has been proposed. The blowing agent activator is selected from citric acid, oxalic acid, p-toluene sulfonic acid, phosphoric acid, potassium carbonate, borax, triethanol amine, zinc chloride, zinc acetate, zinc oxide, zinc stearate, barium stearate, calcium stearate, urea and poly(ethylene glycol) (6). 

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