ASTM D5338-15 (R2021) pdf free download.Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions, Incorporating Thermophilic Temperatures.
1.1 This test method determines the degree and rate of aerobic biodegradation of plastic materials on exposure to a controlled-composting environment under laboratory conditions, at thermophilic temperatures. This test method is designed to yield reproducible and repealable test results under controlled conditions that resemble composting conditions, where therrnophiiic temperatures are achieved. The test substances are exposed to an inoculum that is derived from compost from municipal solid waste. The aerobic composting takes place in an environment where temperature, aeration and humidity are closely monitored and controlled.
1.2 This test method is designed to yield a percentage of conversion of carbon in the sample to carbon dioxide. The rate of biodegradation is monitored as well.
1.3 This test method is designed to be applicable to all plastic materials, which are intended to be composted in facilities that achieve thermophilic temperatures.
1.4 The values slated in SI units are to be regarded as the standard.
3. Terminology
3. 1 Definitions—Definitions of terms applying to this test method appear in Terminology D883.
4. Summary of Test Method
4.1 This test method consists of the following:
4.1.1 Selection of plastic material for the deerminaiion of the aerobic biodegradability in a controlled-composting system,
4.1 .2 Obtaining an inoculum from composted municipal solid waste,
4.1.3 Exposing the test substances to a controlled aerobic composting process in conjunction with the inoculum,
4.1 .4 Measuring carbon dioxide evolved as a function of time, and
4.1 .5 Assessing the degree of biodegradability.
4.2 The percentage of biodegradability is obtained by determ ining the percentage of carbon in the test substance that is converted to CO, during the duration of the test. This percentage of biodegradability will not include the amount of carbon converted from the test substance that is converted to cell biomass and that is not, in turn, metabolized to CO, during the course of the test.
4.3 The disintegration of a compact test material is visually determined at the end of the test. Additionally, the weight loss of the test material may he determined.
5. Significance and Use
5.1 Biodegradation of a plastic within a composting unit is an important phenomenon because it may affect the decomposition of other materials enclosed by the plastic and the resulting quality and appearance of the composted material. Biodegradation of plastics will also allow the safe disposal of these plastics through large, professionally-managed composting plants and well-run residential units, where thermophilic temperatures are achieved. This procedure has been developed to permit the determination of the rate and degree of aerobic biodegradability of plastic products when placed in a controlled composting process.
5.2 Limitations—Because there is a wide variation in the construction and operation of composting facilities and because regulatory requirements for composting systems vary, this procedure is not intended to simulate the environment of any particular composting system. However, it is expected to resemble the environment of a composting process operated under opti mum conditions where thermophi lie temperatures are achieved. More specifically, the procedure is intended to create a standard laboratory environment that will permit a rapid and reproducible determination of the aerobic biodegradability under controlled composting conditions.ASTM D5338 pdf download.