Test Methods to Validate Claims: The need exists for skillful testing to validate of claims regarding compostability. Unproven or false claims of compostability harm consumers and generally contaminate the market place. Prior to testing standards such as ASTM D6400 (USA) and EN 13432 (EU), scientists relied on well-known laboratory biodegradability procedures based on published science. A common parameter is measuring evolved CO2. This basic science of biodegradation applies to compostability and is a foundation for current methods and advanced studies.
In ASTM and EN tests, all CO2 that is evolved from compost is captured.
Emergence of Standards: After 1995, standardized protocols to distinguish compostability as distinct from bio-degradability emerged. The family of tests are known as ASTM D6400 (USA) and EN 13432 and ISO 14855 (Europe). These test protocols are essentially equivalent to each other.
Compostable vs Biodegradable: Biodegradability is a significantly broader category than compostability since it encompasses ambient environments. The new protocols for compostability testing originated from industry and appear to be mainly based on thermoplastic material such as PLA which has an elevated melting point (Tg) of 55°C. Synthetic plastics with fixed melt points must be exposed to temperatures at or above this to reduce molecular weight and trigger hydrolysis before becoming compostable. An extreme case are Oxo-degradable plastics that have trigger points that lie outside biological relevancy. Trigegr points that are within the biological zone provide the convenient leverage to derive a standard requiring thermophilic compost conditions.
Industrial vs Other Composting: A consequence of implementing these temperature-based protocols is the arbitrary distinction of “industrial” (high heat) composting as opposed to “other” forms of composting. Composting, however, is not necessarily more efficient at high temperatures nor is there evidence that compost products are superior due to high temperature processes. Controlling the test process around a high-heat parameter will, however, give thermoplastic materials the best opportunity to reveal their potential degradability, while obscuring plastics that have unique ambient degradability potential.
New advancements in bioplastics including biodegradable polyesters such as Polyhydroxyalkanoates, PVA, and PVOH’s have further blurred the boundary of high-temperature industrial composting, since these products may degrade well at lower temperatures. New forms of PLA are recognized that do not possess the limiting Tg factor. This has resulted in challenges to the ASTM and EN norms to include consideration of non-industrial composting. Woods End Laboratory possesses skilled awareness of this “work-in-progress” for achieving high-quality scientific validation of biodegradable products at temperatures other than accepted industrial norms.
The True Nature of Composting: Composting is best understood as a combination of short periods of thermophilic (high heat) conditions (>45°C or 115F for 3-days to 2 weeks) followed by much longer periods (2 – 6 months) of mesophilic (<45°C or < 115F) behavior. Mesophilic degradation is remarkably efficient. Ideally, test standards would incorporate both heating levels, yet it has proven too difficult to adjudicate mesophilic and thermophilics methods among laboratories. Some European protocols recognize lower temperature or “home type” compost conditions for testing.
Family of Standards: To date the nexus of ASTM, EN and ISO methods for compostability have helped regulate and grow a legitimate and thriving biodegradable plastic movement, with little conflict. Woods End Laboratories grasp of the proper use of these methods and awareness of alternative protocols to round-out claims, make the laboratory extremely successful in pursuing customers’ broad based interests in compostability & biodegradability assurance.
Strength of Satisfied Clients: Woods End’s clients in biodegradability testing include a venerable list with names like: DuPont, DowAgroSciences, FritoLay, KraftFoods, Natureworks, Novamont, Pepsico, Nordenia, Roy. F. Weston, Toray, US Army Environmental Center, Weetabix – and many more.
Adiabatic Compost Chambers – materials placed inside the chamber can be observed biodegrading without the interfering sampling process that often is required in quantitative science.
Decomposition evaluations include carbon-dioxide evolution (ASTM 6338 and ISO 14285), material disintegration (ASTM 6.2 under D6400/EN 13432), and heavy metals plus ecotoxicity measurements.
Biochamber: Also available complementing these protocols is a visual observation chamber permitting time-lapse digital imaging to reveal disappearance. For an example of Woods End’s advanced digital biodegradation work go to: PLA-BAG. A description of one of our customized test-protocols is found at “Behind the Scenes“.
Scanning FTIR is available followed by library-matching to identify molecular composition of proposed bioplastics. This step is also a required component of BPI-certification testing.
Woods End is a successful applicant for BPI-process industry certification.
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