Oxidative degradation and molecular weight change of LDPE buried under bioactive soil for 32-37 years.

Biodegradability and degrading microbes of low‐density polyethylene

“…We have been ascertaining that low-density polyethylene (LDPE) fully exhibits its biodegradability when exposure conditions surrounding the LDPE are ready for its degradation, although its development is very slow. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] For example, LDPE mulch films buried and plowed in fields for several years show notably whitened parts over their whole area due to microscopic pores generated by enzymatic degradation by microbes, which is characteristic biodegradation. 10 Also, in case of mayonnaise bottles, made of LDPE by blow molding process and buried in soil for over 32 years, when their surfaces in contact with the soil have been compared with those not in contact with the soil, the decrease of molecular weight and the remarkable tailing of molecular weight distribution to lower molecular weight side have been recognized at the surfaces in contact with the soil.…”

“…10 Also, in case of mayonnaise bottles, made of LDPE by blow molding process and buried in soil for over 32 years, when their surfaces in contact with the soil have been compared with those not in contact with the soil, the decrease of molecular weight and the remarkable tailing of molecular weight distribution to lower molecular weight side have been recognized at the surfaces in contact with the soil. 5 Furthermore, the observation of the degraded and whitened parts in contact with the soil, with a scanning electron microscope (SEM), has revealed the presence of the colonies of LDPEdegrading bacteria. 3,15 When these notably degraded bottles have been observed in detail after they were cleaned with hydrofluoric acid, numerous pores generated by enzyme degradation with $ 1 to 2 lm in length and 0.5 $ 1 lm in width have been discerned.…”

“…We have been ascertaining that low‐density polyethylene (LDPE) fully exhibits its biodegradability when exposure conditions surrounding the LDPE are ready for its degradation, although its development is very slow 1–15. For example, LDPE mulch films buried and plowed in fields for several years show notably whitened parts over their whole area due to microscopic pores generated by enzymatic degradation by microbes, which is characteristic biodegradation 10.…”

“…For example, LDPE mulch films buried and plowed in fields for several years show notably whitened parts over their whole area due to microscopic pores generated by enzymatic degradation by microbes, which is characteristic biodegradation 10. Also, in case of mayonnaise bottles, made of LDPE by blow molding process and buried in soil for over 32 years, when their surfaces in contact with the soil have been compared with those not in contact with the soil, the decrease of molecular weight and the remarkable tailing of molecular weight distribution to lower molecular weight side have been recognized at the surfaces in contact with the soil 5. Furthermore, the observation of the degraded and whitened parts in contact with the soil, with a scanning electron microscope (SEM), has revealed the presence of the colonies of LDPE‐degrading bacteria 3, 15.…”