ISO 16869-2008 

Plastics — Assessment of the effectiveness of fungistatic compounds in plastics formulations

 

Introduction

It is a well known phenomenon that plasticizers as well as other ingredients in plastics formulations can be attacked by bacteria, yeasts and fungi, the latter being the most important deteriogens. Microbial attack results in a reduction of the quality of the plastic, causing embrittlement as well as discoloration. This deterioration is of economic importance.

The prevention of fungal attack can be achieved by the incorporation of a fungistatic compound into the formulation. The function of this fungistat is to inhibit the growth of any fungi present on the surface of the plastic product.

The method described in this International Standard determines the effectiveness of fungistatic compounds incorporated into the plastic against the fungi used in the test.

WARNING — Handling and manipulation of microorganisms that are potentially hazardous requires a high degree of technical competence and may be subject to current national legislation and regulations. Only personnel trained in microbiological techniques should carry out such tests. Codes of practice for disinfection, sterilization and personal hygiene must be strictly observed.

It is recommended that workers consult IEC 60068-2-10:2005, Annex A “Danger to personnel”, and ISO 7218, Microbiology of food and animal feeding stuffs — General requirements and guidance for microbiological examinations.

 

1   Scope

This International Standard specifies a method for determining the effectiveness of fungistatic compounds in protecting susceptible ingredients like plasticizers, stabilizers, etc., in plastics formulations. The method demonstrates whether or not a plastic product is actively protected against fungal attack.

The evaluation is by visual examination.

The test is applicable to any articles made of plastic that are in the form of films or plates no thicker than 10 mm. In addition, porous materials such as plastic foams may be tested provided that they are in the above-mentioned form.

A minimum diffusion of the fungicides that migrate out of the matrix is necessary with this procedure.

In contrast to ISO 846, the test films are not sprayed with a fungal spore suspension but covered with a layer of test agar containing spores. It has been found that this leads to a better distribution of the spores as well as providing a good supply of water necessary for spore germination on plastic surfaces that are normally hydrophobic.

 

2   Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 291:2008, Plastics — Standard atmospheres for conditioning and testing

 

3   Terms and definitions

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

3.1

plastic susceptible to fungal attack

plastic material that contains in its formulation one or more nutrients that support fungal growth

3.2

fungistat

compound that prevents fungal growth on a material that is normally susceptible to fungal attack