ISO 16929:2021 Plastics — Determination of the degree of disintegration of plastic materials under defined composting conditions in a pilot-scale test

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Plastics — Determination of the degree of disintegration of plastic materials under defined composting conditions in a pilot-scale test由ISO于2021-03发布，适用于世界范围。

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Plastics — Determination of the degree of disintegration of plastic materials under defined composting conditions in a pilot-scale test

1 Scope

This document defines a test method used to determine the degree of disintegration of plastic materials in a pilot-scale aerobic composting test under defined conditions. It forms part of an overall scheme for the evaluation of the industrial compostability of plastics as outlined in ISO 17088. The test method laid down in this document is also used to determine the influence of the test material on the composting process and the quality of the compost obtained. This test method cannot be used to determine the aerobic biodegradability of a test material. NOTE Other methods are available for this test (for example, see ISO 14851, ISO 14852 or ISO 14855-1 and ISO 14855-2).

2 Normative references

There are no normative references in this document.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://w ww. iso. org/ obp

— IEC Electropedia: available at http:// www .electropedia. org/ 3.1

degradation

irreversible process leading to a significant change in the structure of a material, typically characterized by a loss of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by fragmentation, affected by environmental conditions, proceeding over a period of time and comprising one or more steps

3.2

biodegradation

degradation (3.1) caused by biological activity especially by enzymatic action leading to a significant change in the chemical structure of a material

3.3

disintegration

physical breakdown of a material into very small fragments

3.4

compost

organic soil conditioner obtained by biodegradation (3.2) of a mixture principally consisting of various vegetable residues, occasionally with other organic material, and having a limited mineral content

3.5

composting

aerobic process designed to produce compost (3.4)

3.6

compostability

property of a material to be biodegraded in a composting (3.5) process

3.7

maturity of compost

assignment of the maturity of a compost (3.4) based on the measurement of the maximum temperature in a self-heating test using Dewar vessels

Note 1 to entry: It is expressed in terms of the so-called “Rottegrad” (see 6.2.3.1).

3.8

total dry solids

amount of solids obtained by taking a known volume of test material or compost (3.4) and drying at about 105 °C to constant mass

3.9

volatile solids

amount of solids obtained by subtracting the residues of a known volume of test material or compost (3.4) after incineration at about 550 °C from the total dry solids (3.8) content of the same sample

Note 1 to entry: The volatile solids content is an indication of the amount of organic matter present.

4 Principle

The disintegration test is performed under defined and standardized composting conditions on a pilot-

scale level.

The test material is mixed with fresh biowaste in a precise concentration and introduced into a defined composting environment. A natural ubiquitous microbial population starts the composting process spontaneously and the temperature increases. The composting mass is regularly turned over and mixed. Temperature, pH-value, moisture content and gas composition are regularly monitored. They should fulfil certain requirements to ensure sufficient and appropriate microbial activity. The composting process is continued until a fully stabilized compost is obtained. This is usually the case after 12 weeks.

The compost is visually observed at regular time intervals to detect any adverse effect of the test material on the composting process. At the end of the test, the maturity of compost is determined, and the mixture of compost and test material is sieved through 2 mm and 10 mm mesh sieves. The disintegration of the test material is evaluated based on the total dry solids by comparing the fraction of test material retained by the 2 mm sieve and the amount tested. The compost obtained at the end of the composting process may be used for further measurements, such as chemical analyses and ecotoxicity tests.

5 Apparatus

5.1 Composting environment.

5.1.1 General

The composting environment may be either a pilot-scale composting bin or nets buried in a pilot-scale composting bin. The volume of each bin shall be high enough for natural self-heating to occur. Sufficient and even aeration shall be provided by an appropriate air supply system. To standardize conditions for the test, the composting trials can be run in bins which are placed in a climatic chamber with a constant chamber temperature or in insulated bins.

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