A literature review of the chemical nature and toxicity of the decomposition products of polyethylenes

Abstract

The literature on polyethylenes has been reviewed with an emphasis on the identification of gaseous products generated under various thermal decomposition conditions and the toxicity of those products. This review is limited to publications in English through 1984. The analytical chemical studies of the thermal decomposition products generated under vacuum, inert and oxidative experimental conditions are described. In oxidative atmosphere, which most closely simulate real fire conditions, carbon monoxide (CO) was found to be the predominant toxicant. Acrolein was another toxicant often noted in these reviewed studies. More acrolein was generated under non‐flaming than under flaming conditions. Results from seven different test procedures were considered in assessing the acute inhalation toxicity of combustion products from various polyethylene formulations. The combustion products generated from the polyethylenes studied in the non‐flaming mode appeared to be slightly more toxic than those produced in the flaming mode. In the non‐flaming mode the LC50 values ranged from 5 to 75 mg l−1. In the flaming mode the LC50 values ranged from 31 to 51 mg l−1. The toxicity of the degradation products of polyethylenes appears to be similar to that found for other common materials designed for the same end uses.

Catalytic Thermal Decomposition of Polyethylene by Pyrolysis Gas Chromatography

“…The observed volatiles during pyrolysis were identified as ethylene, propylene, isobutylene, 1-hexene and heptane. These volatiles products are formed as a result of scission of C-C bonds 7,8 . The effect of temperature on the %yield of these products is reported in Figure 1.…”

Polyolefins and the environment

“…For random degradation to occur the polymer chain does not necessarily require to carry any active site [38]. The mechanism of thermal degradation of PE has also been discussed as an example for random scission type reactions [39]. PE also undergoes random degradation through migration of a hydrogen atom from one carbon to another thus generating two fragments [40].…”

Effect of low-density polyethylene on smoke emissions from burning of simulated debris piles

“…Due to the widespread presence of polyethylene (and other plastics) in municipal waste and the use of combustion as a waste disposal mechanism, several studies have examined the pyrolysis and combustion products of PE (Conesa et al, 1994;Kolb et al, 1965;Paabo and Levin 1987;Shemwell and Levendis, 2000;Wheatley et al, 1993). Paabo and Levin (1987) concluded in their literature review that "the toxicity of the combustion products from various samples of polyethylenes [is] not highly or unusually toxic."…”

“…Paabo and Levin (1987) concluded in their literature review that "the toxicity of the combustion products from various samples of polyethylenes [is] not highly or unusually toxic." Linak et al (1989) measured emissions produced by burning piled black LDPE (agricultural plastic) under no-wind and simulated air-curtain incineration conditions and found little difference in the variety and quantity of organic compounds between the burning techniques.…”