Plast

This document specifies a method for determining the flexural properties of rigid and semi-rigid plastics under defined conditions. A preferred test specimen is defined, but parameters are included for alternative specimen sizes for use where appropriate. A range of test speeds is included. The method is used to investigate the flexural behaviour of the test specimens and to determine the flexural strength, flexural modulus and other aspects of the flexural stress/strain relationship under the conditions defined. It applies to a freely supported beam, loaded at midspan (three-point loading test). The method is suitable for use with the following range of materials: — thermoplastic moulding, extrusion and casting materials, including filled and reinforced compounds in addition to unfilled types; rigid thermoplastics sheets; — thermosetting moulding materials, including filled and reinforced compounds; thermosetting sheets. In agreement with ISO 10350-1[5] and ISO 10350-2[6], this document applies to fibre-reinforced compounds with fibre lengths ≤7,5 mm prior to processing. For long-fibre-reinforced materials (laminates) with fibre lengths >7,5 mm, see ISO 14125[7]. The method is not normally suitable for use with rigid cellular materials or sandwich structures containing cellular material. In such cases, ISO 1209-1[3] and/or ISO 1209-2[4] can be used. NOTE 1 For certain types of textile-fibre-reinforced plastic, a four-point bending test is used. This is described in ISO 14125. The method is performed using specimens which can be either moulded to the specified dimensions, machined from the central section of a standard multipurpose test specimen (see ISO 20753) or machined from finished or semi-finished products, such as mouldings, laminates, or extruded or cast sheet. The method specifies the preferred dimensions for the test specimen. Tests which are carried out on specimens of different dimensions, or on specimens which are prepared under different conditions, can produce results which are not comparable. Other factors, such as the test speed and the conditioning of the specimens, can also influence the results. NOTE 2 Especially for injection moulded semi-crystalline polymers, the thickness of the oriented skin layer, which is dependent on the moulding conditions, also affects the flexural properties. The method is not suitable for the determination of design parameters but can be used in materials testing and as a quality control test.

This test method covers the determination of the low-rate fracture toughness (JIc) of plastics exhibiting a ductile behaviour and characterized by a macroscopically stable crack growth during a fracture test. The application of standard LEFM tests to these materials typically fails due to the excessive non-linearity in the response. This test method, developed for the SEN(B) testing configuration, describes a single-specimen approach that does not require the measurement of Δa. Not intended to provide a method to construct the material JR curve, this test method allows checking a priori the applicability of the multi-specimen approach based on the Δa measurement for the construction of the material JR curve to a ductile polymer with given specimen geometry and dimensions. This is done by referring to a specially developed crack propagation parameter, which is labelled mS.

This document defines test methods and criteria for distinguishing intrinsically biodegradable plastic materials from those that are persistent. Biodegradability is inferred from biodegradation tests conducted under aerobic conditions, i.e. under the conditions typically found in most natural habitats. Plastics that undergo ultimate biodegradation under aerobic conditions in a manner similar to natural polymer materials are defined as biodegradable plastics. This document describes a method for distinguishing between non-biodegradable plastics, which do not biodegrade even when environmental conditions are favourable for biodegradation (including aerobic conditions), and biodegradable plastics, i.e. those that biodegrade upon contact with active microorganisms when environmental conditions are favourable for biodegradation.

The aim is to demonstrate ultimate aerobic biodegradability of plastic materials, i.e. the intrinsic potential for conversion to carbon dioxide, water and biomass by aerobic microorganisms in an oxygen-rich environment, which is representative of most natural environments.

The potential for biodegradation should be verified using alternative tests and criteria, if a deposition in a permanent anaerobic environment (e.g. deep subsurface environments, wetlands and swamps, anoxic zones in oceans and lakes) is expected.

NOTE          Currently, there are no methodologies or criteria available to verify accumulation due to the lack of biodegradation of plastics in such anaerobic habitats.

The plastic materials identified as intrinsically biodegradable following this document can be used in the design of products with a high risk of dispersion whenever the use of biodegradable components is searched by the designer. Intrinsically non-biodegradable components are not susceptible to biodegradation and therefore cannot be removed from the environment by the action of micro-organisms. This factor tends to increase the residence time of products in the environment. In addition, their eventual degradation, mainly due to abiotic factors, results in persistent fragments (microplastics).

The test scheme described in this document is not specific to any particular application. Rather, it is a framework methodology that can be used in different industries to identify biodegradable plastics that can be used to make different types of products and for different applications. For the characterisation and environmental assessment of products placed on the market containing plastics identified as biodegradable according to this document, reference is made to the specific product standards, where available. This document only deals with the definition of intrinsic biodegradability of plastic materials, without defining the hazard of the products, which requires a specific assessment that is beyond the scope of this document. The rate of biodegradation of a plastic object as a function of environmental conditions cannot be determined from this document. Therefore, this document is not sufficient to carry out an analysis of the ecological risk associated with the dispersal of products, as this requires an assessment of the intrinsic hazard, of the environmental fate, in addition to the assessment of biodegradability.

The methodology described in this document does not apply to applications covered by mandatory regulations.