Study of the thermal oxidation of polyole‐fins. V. Volatile products in the thermal oxidation of polyethylene

Abstract

Organic volatiles formed in the thermooxidation of polyethylene at 150 and 160°C, 760 torr oxygen pressure were investigated by gas chromatographic analysis. Aldehydes and ketones having a linear chain were identified as the major components of the organic fragments investigated. Their concentration in the gas phase was found to decrease with increasing molecular weight; the main component was acetaldehyde which was present in an amount exceeding that of any other component by nearly one order of magnitude. A considerable amount of ethylene and low molecular weight alcohols was also found in the degradation atmosphere. The evolution kinetics of the volatile products has been described by S type curves very similar to those of oxygen absorption with the period of maximum slopes coinciding with maximum hydroperoxide content in the polymer. Organic compounds are estimated to constitute only a small percent of the total amount of volatiles, in accordance with previous observations, recording that water is the dominant component.

High Performance Graphitic Carbon from Waste Polyethylene: Thermal Oxidation as a Stabilization Pathway Revisited

“…To date, the thermal oxidation of polyethylene has only been considered as a degradation route that deteriorates LLDPE mechanical properties. − In this study, however, we took advantage of chemical structural changes taking place during the thermal oxidation process, and thereby utilized thermal oxidation to reorganize the aliphatic LLDPE structure into one that was favorable for carbonization. Previous studies only considered LLDPE oxidation behavior in the low temperature regime, under 200 °C. − , Reported chemical changes included limited cross-linking, oxygen functionalization, and chain scission. These changes were sufficiently severe to induce significant degradation in mechanical properties and thus the polymer’s oxidation behavior in the higher temperature regime was not investigated.…”

“…Previous studies only considered LLDPE oxidation behavior in the low temperature regime, under 200 °C. [23][24][25][26]31 Reported chemical changes included limited cross-linking, oxygen functionalization, and chain scission. These changes were sufficiently severe to induce significant degradation in mechanical properties and thus the polymer's oxidation behavior in the higher temperature regime was not investigated.…”

Mechanisms of Crosslinking, Oxidative Degradation and Stabilization of UHMWPE

“…The alkoxy radical formed through Reaction 21 can decompose via -scission, according to Reactions 28 and 29 (Scheme 10), with the formation of a methyl chain end, whose increase has been observed in the post-irradiation oxidation process, and of a carbonyl radical, which in turn decomposes giving a primary macroalkyl radical and carbon monoxide (CO), commonly found among the products of irradiation or thermo-oxidation of PE [2,30]. Primary alkyl macroradicals react with oxygen to form primary hydroperoxides, then the hydroperoxides decomposition results in the formation of acids, as already stated in the literature [28].…”

Influence of Calcium Oxide (Quicklime) On the Hydrostatic Pressure Resistance of Microporous Polyethylene Films

“…In addition to desiccant, pinholes may occur due to polymer degradation by atmospheric oxygen, especially at elevated temperatures encountered in extrusion and injection molding processes. Several researchers [2][3][4] have investigated and discussed the thermo-oxidative degradation of polyethylene (PE). But there are few publications focusing on the degradation of PE blended with CaCO 3 and CaO in commercial film production.…”

“…Oxygen Oxidative degradation is the primary cause leading to deterioration of polyolefins, and even very small amounts of oxygen can cause drastic changes in the polymer and destroy its useful properties [7]. Several researchers [2][3][4]8,9], have investigated and discussed the thermooxidative degradation of PE. The commonly agreed mechanism involves formation of alkyl radicals (R ) through cleavage of covalent bonds, followed by reaction with oxygen to form peroxides (ROOH) in a chain reaction, as shown in Equation (3).…”