ISO 178:2019 塑料 弯曲性能的测定

标准编号：ISO 178:2019

中文名称：塑料 弯曲性能的测定

英文名称：Plastics — Determination of flexural properties

发布日期：2019-04

标准范围

本文件规定了在规定条件下测定刚性和半刚性塑料弯曲性能的方法。定义了首选试样，但在适当的情况下，还包括用于替代试样尺寸的参数。包括一系列测试速度。该方法用于研究试样的弯曲性能，并确定在规定条件下的弯曲强度、弯曲模量和弯曲应力/应变关系的其他方面。它适用于在跨中加载的自由支撑梁（三点加载试验）。该方法适用于以下材料范围:-热塑性模塑、挤压和铸造材料，包括填充和增强化合物，以及未填充类型；硬质热塑性塑料板；-热固性模塑材料，包括填充和增强化合物；热固性板材。根据ISO 10350-1[5]和ISO 10350-2[6]，本文件适用于具有纤维长度的纤维增强复合材料≤加工前7.5毫米。对于具有纤维长度的长纤维增强材料（层压板）>；7.5毫米，见ISO 14125[7]。该方法通常不适用于刚性多孔材料或含有多孔材料的夹层结构。在这种情况下，可以使用ISO 1209-1[3]和/或ISO 1209-2[4]。注1:对于某些类型的纺织纤维增强塑料，使用四点弯曲试验。ISO 14125对此进行了描述。该方法使用的试样可模制至规定尺寸，从标准多用途试样（见ISO 20753）的中心部分加工，或从成品或半成品加工-成品，如模塑件、层压板或挤压或铸造板材。该方法规定了试样的首选尺寸。对不同尺寸的试样或在不同条件下制备的试样进行的试验可能会产生不可比的结果。其他因素，如试验速度和试样条件，也会影响结果。注2:特别是对于注射成型的半结晶聚合物，定向表皮层的厚度（取决于成型条件）也会影响弯曲性能。该方法不适用于确定设计参数，但可用于材料试验和质量控制试验。

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.

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