The fate of ‘biodegradable’ plastics in municipal leaf compost

Plant polymers for biodegradable plastics: Cellulose, starch and polyhydroxyalkanoates

“…Small proportions of starch (5-15~o) can be blended with polyethylene, poly(vinylchloride), polypropylene and polystyrene. Claims to improve the biodegradability of the synthetic polymer by starch addition could not be verified when standards for biodegradation were developed, for example by the American Society for Testing and Materials (ASTM) [33,5,29,47,97]. Even the biodegradation of starch itself is reduced, probably because of its inaccessibility to enzymes [87].…”

Microbiological Degradation of Polymeric Materials

“…In addition, enzymatic assays have been used to assess degradability of a specific polymer under laboratory conditions [86,[94][95][96] or to detect specific enzyme activity indicative of a degradative process, for example, esterases [12,[97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112]. Experiments in situ always suffer from poor reproducibility because of the broad range of variables involved [83,84] and the difficulty in interpretation of experimental results and extrapolation of possible mechanisms involved. In contrast, laboratory-simulated conditions with high reproducibility are often used for evaluation of the fate of polymeric materials and investigation of the degradation mechanisms involved [4,6,38,[39][40][41][42][43][44][45]113].…”

Biodegradability of chemically synthesized syndiotactic poly(β-[R]- hydroxybutyrate) in soil of Northeast China

“…syn-PHB was previously shown to be hydrolyzable by extracellular enzymes of Penicillium funiculosum (Kemnitzer et al, 1992) and by aqueous water (Doi,1990). Bacterial PHBs were previously reported to be degraded in thermophilic composting (Gilmore et al, 1992), soil (Barak et al, 1991;Mergaert et al, 1993), marine (Wirsen and Jannasch, 1993) and sewage sludge (Budwill et al, 1992). In the current study, the controls showed approximately 7.3% weight loss by the end of 90 days of incubation presumably due to surface erosion and hydrolysis (Figure 1).…”

“…One example is the crystalline poly ([R]-β-hydroxybutyrates) (PHBs) which can be degraded under both aerobic (Doi, 1990;Gilmore et al, 1992;Wirsen and Jannasch, 1993) and anaerobic conditions (Budwill et al, 1992;Mas-Castellà et al, 1995). Bacterial PHBs have only the [R] stereochemical configuration and the thermoplastics are isotactic, in contrast chemical synthesis may result in an array of stereochemical configurations depending on the catalysts and reaction condition.…”