ISO 23948:2023 プラスチック | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 4, Burning behaviour.

Introduction

Polyvinyl chloride (PVC) is an example of an intumescent material that leaves much of the original carbon content as a solid residue. The presence of chlorine in PVC exerts its influence in two ways, causing an increase in:

• hydrogenated char formation (meaning that less flammable decomposition products are formed);
• generating HCl, which then acts as a gas phase scavenger slowing down further reactions of flammable products in the gas phase. [- CH₂ – CHCl- → - CH = CH - + HCl]

The expansion formed has two positive effects regarding fire safety:

• it is a barrier between the source of heat and the unaffected polymer material leading to a reduction of its rate of decomposition;
• it reduces the release of flammable gas.

ISO/TR 20118 provides information on fire properties of PVC materials.

The intumescent properties of PVC materials and products are likely, however, to be affected by their exact formulation and by the use of specific chemical species (e.g. intumescent chemicals), as processing aids or other components of the specific material. The aim of this document is to propose a test method to characterize the intumescence properties of PVC materials and products, by using the cone calorimeter heater as defined in standards ISO 5660-1, ISO 13927 and ISO 17554.

In this test method, the expansion of PVC materials and products is determined by the measurement of the height increase of a specimen when exposed to the radiated heat produced by an electrical conical heater. Intumescence is a property given to, or pre-existing in, some materials and used in fire safety as a way to increase fire performance and protect materials or products with regard to either reaction-to-fire or fire resistance.

1 Scope

This document specifies a test method for assessing the expansion of PVC materials and products during their combustion under the effect of heat radiation.

This test method is also applicable to materials and products made from blends and mixtures of PVC with other polymers, such as PVC blended with a copolymer of styrene and acrylonitrile (PVC-SAN).

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 1043-1, ISO 1043-4, ISO 13943 and the following apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

Bibliography