ISO 846 Determination of the degradation behavior of plastics under the action of fungi and bacteria
Introduction to ISO 846
Under certain climate and environmental conditions, microorganisms can grow and reproduce on the surface of plastic or plastic products.
They and/or their metabolites can not only destroy the plastic itself, but can also affect the reliability of building materials and systems containing plastic components.
The behavior of microorganisms on plastic is affected by two different processes:
1 ) Direct effect: Due to the deterioration of plastic, nutrients are provided for the growth of microorganisms.
2 ) Indirect effects: effects caused by microbial metabolites, such as discoloration or further deterioration.
The ISO 846 national standard involves these two processes and their combined effects.
Plastics - Determination of microbial behavior
This standard describes methods for the determination of plastic degradation due to the action of fungi, bacteria and soil microorganisms.
The type and degree of deterioration can be determined by the following methods:
a ) Visual inspection
b ) Quality changes
c ) Changes in other physical properties
This test applies to all plastic products that have a flat surface and are therefore easy to clean. Exceptions include porous materials such as foam.
ISO 846 reference standard
The provisions contained in the following standards constitute provisions of this standard through reference in this standard. When this standard is published , the versions shown are valid.
All standards are subject to revision . Parties using this standard should explore the possibility of using the latest edition of the following standards . Members of IEC and ISO should
Preserve currently valid international standards.
IS0291: Plastics - Standard environment for conditioning and testing
IEC68-2-10: Basic environment of the experimental process - Part 2 : Experiment 1 Experiment J and guidance : Mold growth
ISO 846 test specimen
1 Shape and size The shape and size of the sample are determined by the following fungi, bacteria or soil exposure experiments to be done.
If the change in sample thickness needs to be measured , the sample used must be taken from the original material . If the material needs to be formed before use ,
The maximum thickness of the sample used is 0.5mm. If the change in sample mass needs to be measured , use a side length of 30mm~60mm.
***For square samples with a thickness of 2 mm , when visual inspection is used to evaluate changes in the appearance of the sample , the size requirements of the sample are not strict .
Only the sample thickness is recommended to be 0.5-2mm. Because microorganisms can affect the surface of the experimental sample , only use the same size
Only by conducting experiments on samples can the results be comparable.
2 sample groups and quantity of each group
2.1 Sample group For each sample and each experimental method , prepare three groups of samples : Group 0 : control sample , stored under standard temperature and humidity conditions ;
Group : samples inoculated with microorganisms and cultured ; Group S : sterilized samples , stored under the same conditions as Group 1 .
2.2 When visually inspecting the quantity of each group , prepare at least 5 samples for each group , that is, a total of at least 15 samples for each sample and each experimental method .
When measuring mass changes , prepare at least 6 samples for each group , that is, a total of at least 18 samples for each sample and each experimental method .
For other evaluation methods , use the sample quantities described in the reference standards. Various evaluation experiments were conducted separately.
However , specimens used to measure changes in mass or other physical properties may also be used for visual inspection ( experimentation ) .