Degradable plastic products testing is the scientific verification of the biodegradation rate, disintegration behavior, chemical safety, and ecological impact of materials such as PLA, PBAT, PBS, and PHA. Performed by accredited third-party laboratories in accordance with ISO, ASTM, EN, and GB standards, these tests are essential for compostability certification, regulatory compliance, and credible environmental claims. This guide explains the key testing samples, testing items, testing methods, and applications involved.
Technical Overview
Degradable plastics are polymeric materials engineered to break down through the enzymatic action of microorganisms into water, carbon dioxide (or methane under anaerobic conditions), and biomass. The most widely used materials include polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxyalkanoates (PHA), polycaprolactone (PCL), and starch- or cellulose-based blends. Because degradation performance cannot be judged from appearance, product labeling, or marketing statements alone, laboratory testing is the only technically defensible basis for claiming that a product is genuinely biodegradable or compostable.
Testing of degradable plastic products is built on four pillars: controlled biodegradation measurement, disintegration performance, chemical safety (heavy metals and regulated substances), and ecotoxicity of the resulting compost. The governing frameworks include EN 13432 and EN 14995 in Europe, ISO 17088 and ISO 18606 at the international level, ASTM D6400 and ASTM D6868 in North America, and GB/T 20197, GB/T 38082, and GB/T 41010 in China. Products that merely fragment into microplastics through oxidative breakdown do not satisfy these frameworks and cannot be marketed as biodegradable.
Key Performance Criteria
- Biodegradation: at least 90% of the theoretical carbon dioxide evolution within a maximum of 6 months under industrial composting conditions.
- Disintegration: at least 90% of the product mass must fragment to pieces smaller than 2 mm within 12 weeks of composting.
- Chemical safety: concentrations of heavy metals and toxic elements must remain below the regulated limits for compost.
- Ecotoxicity: the resulting compost must not inhibit seed germination or plant biomass production compared with a blank control.
- Organic content: volatile solids must constitute at least 50% of the dry mass of the material.
Testing Samples
Flexible Films and Bags
Compostable shopping bags, waste bags, mailer bags, food-contact wrap, cling films, and agricultural mulch films are among the most frequently tested products. Film samples are typically tested in cut-sheet form, and their formulation must be representative of the commercial product, including printing inks and adhesives where applicable.
Rigid Packaging and Food Service Items
Cups, trays, cutlery, straws, plates, coffee capsules, thermoformed containers, bottles, and closures made from PLA, PBS, or biocomposites fall into this category. Multi-component items such as lined coffee cups may require separate testing of the coating or liner to confirm overall compostability.
Raw Resins, Masterbatches, and Additives
Resin producers and compounders verify biodegradation performance at the pellet or powder stage before downstream conversion. Additives, plasticizers, pigments, and pro-oxidant masterbatches are also screened, since non-degradable additives are a common cause of test failure.
Fibers, Nonwovens, and Hygiene Products
Wet wipes, sanitary products, nonwoven bags, face-mask components, and coated paper products are increasingly subject to degradability requirements. These samples often require special preparation because binders and spunbond layers can significantly alter disintegration behavior.
Sample Preparation and Quantity
Most biodegradation standards require the test material to be reduced to a defined particle size, typically less than 1 mm powder or specified-dimension pieces, to ensure homogeneous exposure. A complete test program generally consumes between 0.5 kg and 3 kg of material. Documentation such as formulation data, production batch records, and declared organic carbon content greatly improves test efficiency and accuracy.
Testing Items
Testing programs for degradable plastics combine biological, chemical, and physical test items. The exact scope depends on the target market, the intended disposal environment, and the certification or regulatory requirement involved.
Biodegradation Performance
- Ultimate aerobic biodegradation under controlled industrial composting conditions.
- Aerobic biodegradation in an aqueous medium using activated sludge or defined inoculum.
- Anaerobic biodegradation in high-solids digestate and in aqueous anaerobic systems.
- Biodegradation in soil and marine environments for open-environment claims.
Disintegration and Compost Quality
- Disintegration degree in pilot-scale or laboratory composting reactors.
- Volatile solids and total organic carbon content of the test material.
- Compost maturity assessment and residual manometric respiration activity.
Chemical Safety
- Heavy metals and metalloids: arsenic, cadmium, chromium, copper, mercury, molybdenum, nickel, lead, selenium, zinc, and fluorine.
- Regulated organic substances and volatile organic compounds where required by the target scheme.
Ecotoxicity
- Seed germination rate and plant biomass production using at least two plant species.
- Earthworm acute toxicity testing for soil organism safety.
- Aquatic toxicity screening with algae or daphnia when marine or freshwater claims are made.
Composition and Physical Properties
- Bio-based carbon content determined by radiocarbon analysis.
- Material identification by infrared spectroscopy, thermal analysis, and molecular weight distribution.
- Mechanical properties such as tensile strength, elongation, tear resistance, and melt flow rate for quality verification.
Testing Methods
Aerobic Biodegradation in Controlled Composting (ISO 14855-1, ASTM D5338, GB/T 19277.1)
The test material is mixed with mature, inert compost and incubated at approximately 58 degrees Celsius with continuous aeration. The carbon dioxide evolved is measured by infrared gas analysis or respirometry and compared with the theoretical amount calculated from the material's carbon content. Cellulose is used as a positive reference and must exceed 70% biodegradation for the test to be valid. The test runs until a plateau is reached, up to a maximum of six months.
Aerobic Biodegradation in Aqueous Media (ISO 14851, ISO 14852, JIS K 6951)
The material is suspended in a mineral medium inoculated with activated sludge or a mixed microbial population. ISO 14851 measures oxygen demand in a closed respirometer, while ISO 14852 measures evolved carbon dioxide. These methods are suitable for products intended for wastewater treatment disposal routes or for fundamental material screening.
Anaerobic Biodegradation (ISO 15985, ISO 14853, ASTM D5511)
For products entering anaerobic digestion facilities, the material is incubated with high-solids digestate and the biogas produced is measured manometrically. Methane and carbon dioxide yields are used to calculate the biodegradation percentage against the theoretical gas potential of the polymer.
Disintegration Testing (ISO 16929, ISO 20200, EN 13445, GB/T 19811)
Test specimens are composted in pilot-scale windrows or laboratory reactors following a defined temperature profile. After twelve weeks, the output is sieved through a 2 mm screen, and the fraction of original dry mass that fails to pass is determined. At least 90% disintegration is required for compliance with EN 13432 and equivalent frameworks.
Ecotoxicity Assessment (OECD 208, ISO 11269-1)
Compost derived from the disintegration test is blended with reference soil and used to grow at least two plant species. Germination rate and vegetative biomass must reach at least 90% of the blank control, demonstrating that the degraded material leaves no phytotoxic residues.
Heavy Metal Analysis (ICP-OES, ICP-MS, AAS)
Following acid digestion of the sample, elemental concentrations are quantified by inductively coupled plasma optical emission spectrometry, inductively coupled plasma mass spectrometry, or atomic absorption spectroscopy. Typical EN 13432 limits include 0.5 mg/kg for cadmium and mercury, 50 mg/kg for lead and chromium, and 150 mg/kg for zinc, all on a dry-weight basis.
Bio-based Carbon Content (ASTM D6866, EN 16640, ISO 16620-2)
Radiocarbon analysis distinguishes modern biogenic carbon from fossil-derived carbon by measuring the carbon-14 signature of the sample. This test substantiates bio-based content claims, which are increasingly required alongside biodegradability claims in ecolabeling and public procurement.
Soil and Marine Biodegradation (ISO 17556, ASTM D5988, ASTM D6691, ISO 19679)
Open-environment claims require testing at ambient temperatures with soil or seawater inocula. These conditions are far less aggressive than industrial composting, so degradation kinetics are slower and acceptance thresholds must be evaluated against the specific application, such as agricultural mulch film tested in accordance with EN 17033 or GB/T 35795.
Applications
Degradable plastics testing results are used across the entire product lifecycle, from material development to market access and post-market surveillance.
- Compostability certification support for industrial and home composting schemes based on EN 13432, EN 17427, ASTM D6400, and ISO 17088 requirements.
- Regulatory compliance for the European Union packaging and single-use plastics framework and for Chinese national requirements under GB/T 20197 and GB/T 41010 labeling rules.
- Export market access, providing internationally recognized test reports for degradable tableware, bags, and packaging submitted to customs authorities and overseas buyers.
- Research and development, comparing resin grades, evaluating additive effects on biodegradation kinetics, and studying accelerated aging behavior.
- Procurement qualification by retailers, e-commerce platforms, and government tenders that require independent laboratory evidence of degradability claims.
- Agricultural applications, verifying the field performance and ultimate biodegradation of mulch films intended to be incorporated into soil after harvest.
Accredited third-party laboratories issue test reports that manufacturers use to defend green claims, respond to market surveillance inquiries, and reduce the legal risk associated with unsubstantiated environmental statements.
FAQ
What is the difference between degradable, biodegradable, and compostable?
Degradable is a broad term that includes any material that loses properties over time, including simple fragmentation. Biodegradable means the material is converted by microorganisms into water, carbon dioxide or methane, and biomass under defined conditions and within a defined timeframe. Compostable is the strictest claim: the product must satisfy all requirements of EN 13432 or ASTM D6400, including biodegradation, disintegration, heavy metal limits, and ecotoxicity. Materials that only fragment into microplastics through oxidative degradation do not qualify.
How long does a complete biodegradation test take?
Aerobic composting biodegradation tests run until the biodegradation curve plateaus, typically between two and six months. Disintegration testing requires twelve weeks, followed by several weeks for ecotoxicity evaluation. A full program aligned with EN 13432 therefore generally takes four to six months, plus reporting time.
What sample quantity and information should be submitted?
Most programs require between 0.5 kg and 3 kg of homogeneous sample material. Laboratories also request the product formulation or at least the polymer type, organic carbon content if known, and confirmation that the sample represents the commercial article, including any inks, adhesives, and additives.
What is the difference between industrial and home compostability?
Industrial composting tests are conducted at approximately 58 degrees Celsius with active microbial communities, reflecting managed composting facilities. Home composting occurs at ambient temperatures with weaker microbial activity, so corresponding requirements demand slower but more robust degradation, and claims must be supported by lower-temperature test data such as those described in EN 17427.
Do biodegradable plastics degrade in the ocean or in soil?
Not automatically. Most industrially compostable plastics require elevated temperature and humidity to degrade within a practical timeframe. Claims of marine or soil biodegradability must be supported by dedicated testing such as ASTM D6691, ISO 19679, or ISO 17556, and should be interpreted strictly according to the tested environment.
Which standards apply in the major markets?
The European Union relies on EN 13432 for packaging and EN 14995 for plastics; North America uses ASTM D6400 and ASTM D6868; international buyers frequently reference ISO 17088 and ISO 18606; China applies GB/T 20197, GB/T 38082, and GB/T 41010; and Japan maintains the JIS K 6950-series biodegradability standards adopted from the corresponding ISO methods.