Scope:

ASTM D5338 measures the rate and degree of aerobic biodegradation of plastic materials. This is achieved by exposing materials at a particular temperature under a controlled composting environment inside the laboratory. The test is developed to yield reproducible and repeatable test outcomes under stated parameters. ASTM D5338 is used to test materials before they are introduced into the waste stream. 

Test Procedure:

Aerobic Biodegradation test by ASTM D5338 is performed on plastic material in a controlled-composting environment using a bacterial inoculum. The carbon dioxide evolved is measured as a function of time and the degree of biodegradability is assessed. Disintegration of the compact test material is visually determined and also the weight loss of the material is calculated. 

Sample size:

The test samples can be in the form of articles, granules, films, and powder or as specified by ASTM D618 guidelines. 

Data:

The percent of biodegradation is calculated by dividing the average net gaseous-carbon production of the test compound by the original average amount of carbon in the test compound and multiplying by 100;

%biodegradation=[meanC_g(test)−meanC_g(blank)]/C_i×100‌

where:

C_g = amount of gaseous-carbon produced, g, and

C_i= amount of carbon in test compound added, g

The total carbon content of the test material by elemental analysis

Cumulative CO₂ production (in grams)

Standard error of the percentage of biodegradation

95 % confidence limits