Biodegradation testing methods

3 SEM micrographs of biodegradable polymer green composite, tested by the soil burial test. 

In addition to biodegradabUity, another important prerequisite for an ideal biomaterial is cytotoxicity. This is also vital in biomedical applications. Two methods are generally employed for estimating the cytotoxicity of polymers, the direct contact method and the M lT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method. However, an anti-haemolytic test can provide direct evidence of non-cytocompatibiUty and the power of the polymer to protect the cells from harmful free radicals. Red blood cells (RBC) are very susceptible to attack from free radicals which damage the cell membrane, permitting the leakage of haem protein which can then be estimated. This may be done easily under normal laboratory conditions and the method is briefly discussed below. 

In order to conduct this test, erythrocytes are separated from plasma and the buffy coat and washed three times with five volumes of phosphate buffer saline (PBS, pH = 7.4). The RBCs are collected in a centrifuge under specified conditions (3000 g for 10 min at 25°C). The compacted cells are then suspended in four volumes of PBS for the experiment. The surfaces of all the experimental samples are sterilised for 30 min in ultraviolet light under a sterile laminar air hood. 

Rgure 2.5 shows a better RBC haemolysis inhibition of a vegetable oil-based clay nanocomposite than the pristine system as tested by anti-haemolytic assay. 

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There have been numerous communications on the subject of biodegradation test methods, including aerobic compost (30), anaerobic bioreactor (31), general methodology and future directions (32—34), and a fine review article (24). ASTM (22) and MITI (35) have also set forth standard testing protocols for plastics, as shown in Table 2, whereas OECD test methods (29) are more suited to water-soluble polymers. 

G. Swift, Expectations for Biodegradation Testing Methods, International Biodegradable Polymer Workshop, Osaka, Japan, Nov. 1993. 

Cowan, C.E., T.W. Federle, R.J. Larson, and T.C.J. Feijtel. 1996. Impact of biodegradation test methods on the development and applicability of biodegradation QSARs. SAR QSAR Environ. Res. 5 37-49. 

Biodegradation test methods By using the test method summaries of Table 7.1, explain the differences in concept of CEC and Close bottle test. Why the presence of additives (nitrogen and phosphorus excluded) in the lubricants is known to have a significant effect on the rate of biodegradation ... 

Swift G (1994) Expectations for biodegradation testing methods. In DoiY.FukudaK(eds) Biodegradable Plastics and Polymers. Elsevier, pp 228-236... 

The various biodegradability test method standards from ASTM and ISO are as follows ... 

Table 6.6 Biodegradability testing methods and pass levels...

Key words biodegradable polymer, biodegradation, classification of biodegradable polymers, mechanism of biodegradation, testing method, application. 

Biodegradation standards for industrial compost environment require a biodegradation specification standard and a biodegradation test method standard. The specification standards in Europe are for plastics and for packaging. Both specification standards require the use of the same test method. 

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... 

Biodegradation Test Method Standard iSO 14852-1999 (ED114047). Determination of Uitimate Aerobic Biodegradabiiity of Piastic Materiais in an Aqueous Medium—Method by Anaiysis of Evoived Carbon... 

AIB-Vingotte International has a biodegradable home compost test certification for plastic products that references EN 13432 performance specification and other ISO biodegradable test methods. Biodegradation in soil environments is based on International OK Biodegradable Soil standards. Table 8.7 lists the biodegradation standards for home composing. 

E.8.2 Compare the biodegradation test method standards for ASTM D5338 and ISO 14855-2 What are the conditions for each test method What are the positive and negative controls for each ... 

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