塑料制品；载荷下挠度温度的测定第3部分:高强度热固性层压板和长纤维增强塑料

[中文适用范围]： 本文件规定了塑料在受载荷下弯曲变形温度测定的一般试验方法。适用于不同类型的试样和不同的恒定载荷，以适应不同材料的测试需求。具体包括以下内容： - ISO 75-2规定了普通塑料、填充塑料和纤维增强塑料（纤维长度不超过7.5 mm）以及 durokerite 的特殊要求。 - ISO 75-3规定了高强度热固性层压材料和长纤维增强塑料（纤维长度超过7.5 mm）的特殊要求。 该方法适用于评估材料在高温下负载时的相对行为，尽管实际应用中的因素可能与测试条件不同。结果仅用于比较相同室温弯曲模量材料的行为，并不用于设计分析或预测材料在高温下的耐久性。此方法通常被称为热变形温度（HDT）测试。 [外文原描述]： 1.1 This document gives a general test method for the determination of the temperature of deflection under load (flexural stress under three-point loading) of plastics. Different types of test specimen and different constant loads are defined to suit different types of material. 1.2 ISO 75-2 gives specific requirements for plastics (including filled plastics and fibre-reinforced plastics in which the fibre length, prior to processing, is up to 7,5 mm) and ebonite, while ISO 75-3 gives specific requirements for high-strength thermosetting laminates and long-fibre-reinforced plastics in which the fibre length, prior to processing, is greater than 7,5 mm. 1.3 The methods specified are suitable for assessing the relative behaviour of different types of material at elevated temperature under load at a specified rate of temperature increase. The results obtained do not necessarily represent maximum applicable temperatures because, in practice, essential factors, such as time, loading conditions and nominal surface stress, can differ from the test conditions. True comparability of data can only be achieved for materials having the same room-temperature flexural modulus. 1.4 The methods specify preferred dimensions for the test specimens. 1.5 Data obtained using the test methods described are not intended to be used to predict actual end-use performance. The data are not intended for design analysis or prediction of the endurance of materials at elevated temperatures. 1.6 This method is commonly known as the heat deflection temperature or heat distortion temperature (HDT) test, although there is no official document using this designation.