At present, there is no unified standard for testing the degradation performance of biodegradable materials. The methods adopted or prepared by ASTM can be used as the standard methods. The main methods for evaluating the degradation performance of biodegradable materials by biochemical and microbial methods are as follows.
There are two kinds of burial methods: outdoor burial method and indoor burial method. Their microbial sources are mainly microorganisms in the soil. After a certain period of time, the samples are taken out to determine their weight loss, mechanical properties change, or the microbial invasion status in the soil is determined by electron microscopy.
The advantage is that it can reflect the biological decomposition performance under natural environment conditions, while the disadvantage is that the test cycle is long, the test results vary according to soil quality, and the repeatability is poor. Quantitative method of Vettel incubator is to add test samples and nutrient agar to the container and inoculate microorganisms for culture. After a certain period of time, the weight loss of the sample and some physical or chemical changes are analyzed. The advantages of this method are fast degradation, good repeatability and good quantification. The disadvantage is that it can not reflect the actual situation in nature.
Enzymatic analysis added buffer solution and test sample in the container. After enzymatic action for a certain time, the weight loss of the sample was analyzed, the growth of mould was observed visually, and the changes of physical or chemical properties of the sample were analyzed by microscopy.
The advantages are short test cycle, good repeatability and good quantification, while the disadvantages are that it can not reflect the actual situation in nature. Radioactive C14 tracer method uses C14 to label polymer products, produces CO2 under the action of microorganisms, absorbs CO2 by alkaline solution, measures total CO2 by titration, and then uses radioactive attenuation rate to measure the CO2 content of C14. The percentage of CO2 produced by C14 is used to indicate the degree of microbial erosion.
The advantage is that the experimental results are reliable and clear. The biodegradability of samples can be tested by the biodegradability test.