ISO 62-2008 塑料.吸水性的测定

标准号：ISO 62-2008
中文标准名称：塑料.吸水性的测定
英文标准名称：Plastics - Determination of water absorption
标准类型：G31
发布日期：1999/12/31 12:00:00
实施日期：1999/12/31 12:00:00
中国标准分类号：G31
国际标准分类号：83.080.01
适用范围：1.1 This International Standard describes a procedure for determining the moisture absorption properties inthe “through-the-thickness” direction of flat or curved-form solid plastics. This International Standard alsodescribes procedures for determining the amount of water absorbed by plastic specimens of defineddimensions, when immersed in water or when subjected to humid air under controlled conditions. The“through-the-thickness” moisture diffusion coefficient can be determined for single-phase material byassuming Fickian diffusion behaviour with constant moisture absorption properties through the thickness ofthe test specimen. This model is valid for homogeneous materials and for reinforced polymer-matrixcomposites tested below their glass transition temperature. However, some two-phase matrices such ashardened epoxies may require a multi-phase absorption model which is not covered by this InternationalStandard.1.2 Ideally, the best comparison of the water absorption properties and/or diffusion coefficients of materialsshould be carried out only using the equilibrium moisture content of plastics exposed to identical conditions.The comparison of materials using properties at moisture equilibrium does not assume, and is therefore notlimited to, single-phase Fickian diffusion behaviour.1.3 Alternatively, water absorption of plastic specimens of defined dimensions exposed to immersion orhumidity under controlled conditions but for an arbitrary time period can be used to compare different batchesof the same material or for quality control tests of a given material. For this type of comparison, it is essentialthat all test specimens be of identical dimensions and, as nearly as possible, have the same physicalattributes, e.g. surface smoothness, internal stresses, etc. However, moisture equilibrium is not reached underthese conditions. Therefore, results from this type of test cannot be used to compare the water absorptionproperties of different types of plastics. For more reliable results, simultaneous tests are recommended.1.4 The results obtained using the methods described in this International Standard are applicable to mostplastics but are not applicable to cellular plastics, granulates or powders, which can show additionalabsorption and capillary effects. Plastics exposed to moisture under controlled conditions for defined periodsof time provide relative comparisons between them. The tests described for the determination of the diffusioncoefficient may not be applicable to all plastics. Plastics that do not retain their shape when immersed inboiling water should not be compared using method 2 (see 6.4).