bioresources. com
PEER-REVIEWED REVIEW ARTICLE
biodegradability (Rudnik 2012). Biodegradation tests are recommended to select according to the material’s expected application as well as its end -of-life, which can take place in different environments, such as compost, soil, and fresh or marine water (Philp et al. 2013). A few general standards related to biodegradation in compost, soil or a marine environment are listed in Table 1. Oxo-biodegradability often involves the effect of additives, such as metal salts ( e.g. , manganese, iron, cobalt, nickel) that are added to plastics ( e.g. , PE) to expedite the otherwise very slow degradation. The outcome of oxo-biodegradation relates to the generation of non-visible, micro-sized plastic and metal particles (Philp et al. 2013). Testing of these materials is described in the ASTM D6954-18 (2018) standard. The use of oxo-degradable polymers is banned in Germany (Kosior et al. 2006). A few standards for addressing marine degradation exist. In general, plastics that are degraded in marine environments biodegrade and disintegrate into seawater within a certain period without causing any impact on the surrounding marine organisms. In addition, these plastics are required to pass marine toxicity tests, have a very low heavy metal content, and should be industrially compostable (ASTM D6400-12 2012) (Greene 2014). Compostability A compostable material is generally defined as a material that is biodegradable under aerobic conditions and converted into biomass, carbon dioxide, water, and inorganic compounds, in turn, without producing any toxic compounds and disintegrating during the fermentation phase (Mohanty et al. 2000; Kale et al. 2007; Philp et al. 2013). In addition, the compostable material, according to CEN norms, should not cause complications, neither to the composting process, nor to the compost itself (Weber 2000). Compostable polymers are considered as biodegradable, whereas biodegradable polymers are not necessarily compostable, which has higher demands, e.g. , of resulting biodegradation products (Weber 2000; Müller 2005; Kale et al. 2007), heavy metal content (European standard EN 13432 2000), disintegration within a certain time frame, and the requirement that they do not cause problems during the process of composting (Weber 2000). Philp et al. (2013) and Rudnik (2012) have presented multiple standards considering compostability in their publications. Polymers should be tested by relevant ISO, ASTM, and EN standards in order to meet the compostability criteria (Philp et al. 2013). European standard EN 13432 for compostability of packaging is commonly used (Kosior et al. 2006; Philp et al. 2013). Test methods and certification refers to industrial composting (Kosior et al. 2006; Hermann et al. 2011). In industrial composting, the temperature (58±2 °C), humidity, composting cycles (3 months thermophilic and 3 months maturation phase), and aeration conditions are carefully controlled. In contrast, home composting conditions vary widely. In the case of home composts, temperatures are lower and may vary considerably throughout the seasons (Kosior et al. 2006; Song et al. 2009). Moreover, there is no international standard for home compostability (Kosior et al. 2006; Endres and Siebert-Raths 2011; Hermann et al. 2011), and industrially compostable products (EN 13432) may not perform acceptably in home composts (Song et al. 2009; Endres and Siebert-Raths 2011). A certification for home compostable product is available from Vincotte, “OK Compost Home”. This certification follows the EN 13432 testing standard, except that the process takes a longer period of time (365 days instead of 180 days) and requires lower temperatures (20 °C to 30 °C instead of 58
6
Helanto et al. (2019). “ Bio-based barriers ,” B io R esources 14(2), Pg #s to be added.
Made with FlippingBook - Online catalogs