Polyethylene environmental oxidation

Degradation of polyolefins such as polyethylene, polypropylene, polybutylene, and polybutadiene promoted by metals and other oxidants occurs via an oxidation and a photo-oxidative mechanism, the two being difficult to separate in environmental degradation. The general mechanism common to all these reactions is that shown in equation 9. The reactant radical may be produced by any suitable mechanism from the interaction of air or oxygen with polyolefins (42) to form peroxides, which are subsequentiy decomposed by ultraviolet radiation. These reaction intermediates abstract more hydrogen atoms from the polymer backbone, which is ultimately converted into a polymer with ketone functionahties and degraded by the Norrish mechanisms (eq. 

In our ongoing efforts to develop oxidation catalysts that are functional in water as environmentally berrign solvent, we synthesized a water-soluble pentadentate salen ligand with polyethylene glycol side chairts (8). After coordination of copper(II) ions to the salen ligand, a dinuclear copper(II) complex is obtained that is soluble in water, methanol and mixtures of both solvents. The aerobic oxidation of 3,5-di-tert.-butylcatechol (DTBC) into 3,5-di-terr.-butylqitinone (DTBQ) was used as a model reaction to determine the catalytically active species and initial data on its catalytic activity in 80% methanol. 

Since the environmental degradation of polyethylene starts with abiotic oxidation, the determination of abiotic oxidation products is an important step towards establishing the environmental degradation mechanisms and environmental impact of the material. In a secondary process, microorganisms may utilise these abiotic degradation products and the low molecular weight... 

Polyethylene oxide) (PEO) is a semicrystalline water-soluble polymer [64, 65], with a crystallinity that is very sensitive to the thermal history of the sample, making this property interesting as an indicator of degradation. Because it is biodegradable and biocompatible, PEO is a good candidate for environmental and medical applications [66-68]. The mechanisms of thermo- and photo-oxidation of PEO have already been investigated [69, 70] on the basis of IR identification of the oxidation products and are summarized in Scheme 10.1. 

Polyethylene film samples containing pro-oxidant metal additives, LDPE-DCP540, FCB-ZSK15, and FCB-ZSKIO were provided by EPI Environmental... 

OSi Specialties, a subsidiary of Witco, was nudged into action by the U. S. Environmental Protection Agency.53 The problem was loss of methyl and ethyl chloride in the wastewater from a process of making ethers from polyethylene oxide and polypropylene oxide. A complete study of all of the waste streams at the plant resulted in a solution that cost 600,000 dollars and saved 800,000 dollars. This was done by adding a unit that converted the excess methyl chloride from the process to methanol, which could be sold. An attorney for the company says, But if it hadn t made economic sense, we wouldn t have done it. If dimethyl carbonate could be used for the end-capping, there would be no waste salts produced and almost no wastewater. 

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