Disintegrability, compostability standards

DuPont s Biomax product is a standard PET with the addition of three aliphatic monomers to allow degradation to take place. Comparable to PLA, the degradation mechanism is described as an initial attack of water to the special monomers, which are sensitive to hydrolysis. Although it appears that Biomax sufficiently disintegrates under composting conditions, the process of decomposition of the material was too slow to meet accepted standards. 

ISO 14855,1999, Determination of the ultimate aerobic biodegradability and disintegration of plastics under controlled composting conditions - Method by analysis of evolved carbon dioxide. International Stantktrd 14855 1999(E), International Organization for Standardization (ISO), Genive, Switzerland. 

The ISO standards 14852 and 14855 (88,89) have been recently revised in the form of ISO 14855-1 2012 (90). This standards describes a method for the determination of the ultimate aerobic biodegradability of organic plastics materials imder controlled composting conditions by the measurement of carbon dioxide evolved and the degree of disintegration of the plastic at the end of the test. 

According to ASTM requirements 90% of the carbon of the test materials must be assimilated by the compost microorganisms as dociunented by measuring CO2 production, within a six month period, extendable to one year if radiolabelled carbon is used. Moreover, disintegration of the film or article of the use thickness such that less than 10% of the material remains on a 10 mesh screen after sieving must be proved. Safety of compost must be proved by testing phyto- or ecotoxicity using methods listed in the Standard. 

Disintegrability, namely fragmentation and loss of visibility in the final compost (absence of visual pollution). The standard recommends assessment of disintegration through trials on a pilot or full-scale composting plant. Specimens on the test materials are composted with biowaste for three months. The final compost is then screened with a 2 mm sieve. The mass of test material residues with dimension >2 mm shall be less than 10% of the original mass. 

Procedures The test procedures for ISO 17088 standard specifies that three types of tests are performed on the plastic samples. The first test measures the percentage of disintegration of the plastic samples while under hot and moist compost conditions. The plastic samples are weighed prior to exposure to test conditions. The samples are placed in compost soil with the use of a sack, bag, or screened container. The plastic samples are exposed to industrial composting conditions of at least 58°C and 50% moisture for 84 days. The mass... 

S.3.2.3 Biodegradation Test Method Standard iSO 14855-2 (EN 14046) Packaging. Evaiuation of the Uitimate Aerobic Biodegradabiiity and Disintegration of Packaging Materiais under Controiied Composting Conditions. Method by Anaiysis of Reieased Carbon Dioxide... 

Summary This international standard specifies a method for the evaluation of the disintegration of plastic materials while under industrial composting conditions. The testing environment is pilot scale at an industrial compost facility. The mass of plastic sample is measured prior to the test. The samples are placed in a sack or aerated bag with compost soil. The sack is placed in an aerated pile at least 1 meter deep at an industrial compost facility. The compost vessel should be a minimum of 5 liters and a maximum of 20 liters. The concentration is 1% by weight plastic sample and 99% compost. The temperature of the compost pile should be between 40°C and 75°C. The aerated compost pile should be turned twice per week. 

EN 14045 2003, Packaging - Evaluation of the Disintegration of Packaging Materials in Practical Oriented Tests under Defined Composting Conditions, European Committee for Standardization, Brussels, Belgium, 2003. 

Other procedures for the evaluation of disintegration during composting in full-scale testing have been discussed in which the sample is introduced in net bags into a composting pile. However, national or international standards have not been published yet. In addition, for disintegration it is important to validate test procedures by the use of (natural) reference materials. 

ISO 14855, Determination of the Ultimate Aerobic Biodegradability and Disintegration of Plastic Materials under Controlled Composting Conditions - Method by Analysis of Evolved Carbon Dioxide, International Organization for Standardization, Geneva, Switzerland, 1999. 

To meet the requirements of biodegradability under industrial composting conditions (compostable plastics), a plastic must satisfy the primary requirement of complete biodegradability as measured by the microbial conversion of the plastic carbon to CO2 under composting conditions, as discussed in an earlier section. In addition, it has to meet the disintegration and safety criteria to make a claim of compostability. ASTM D6400, ASTM D6868, ISO 17088 and EN 13432 are specification standards for compostable plastics and require ... 

The American standard ASTM 6400 provides standard specifications for compostable plastics and products manufactured from these materials. ASTM 6400, like all other standards, states its scope of validity, defines its concepts, and states the specific requirements (here for compostable materials and/or products). Similar to DIN EN 13432, subsection 6 (Detailed Requirements) describes the chemical tests as well as the general proof of general biodegradability, followed by the test for total disintegration. However, ASTM 6400 provides little detailed information, but rather refers repeatedly to ASTM D6002 regarding test execution. 

This standard is used to determine the degree of disintegration of plastic materials in a pilot-scale aerobic composting test under defined conditions. The test method laid down in this standard can also be used to determine the influence of the test material on the composting process and the quality of the compost obtained. It cannot be used to determine the aerobic biodegradability of a test material. Other methods are available for this (see e.g. ISO 14851,14852 or 14855). 

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