1.1 本试验方法包括测定小于1.0 mm（0.04 in.）的热收缩塑料薄膜和薄板的收缩张力和相关特性，即收缩力和取向释放应力厚描述了两种允许在预定温度下测量收缩力的程序。具体如下: 1.1.1 程序A 设计用于测量试样施加的最大力，当试样快速加热到特定温度时，试样完全不会收缩。 1.1. 2. 程序B 设计用于测量试样施加的最大力，该力允许在约束之前收缩预定量，同时快速加热到特定温度。 1.2 方向释放应力可根据使用程序A获得的数据确定。 1.3 以国际单位制表示的数值应视为标准。括号中的值仅供参考。 1.4 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 注1: 薄膜被任意定义为标称厚度不大于0.25µm（0.010 in.）的薄片。 注2: 没有已知的ISO等效于该试验方法。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 作为制造过程的结果，内部应力被锁定在薄膜中，这些应力可以通过加热释放。 注3: 对于任何给定类型的薄膜或薄片，开始收缩的温度与用于制造薄膜的加工技术有关，也可能与基础树脂中的相变有关。 5.2 收缩张力影响收缩包装应用中薄膜的外观和性能。它还用于确定定向的程度和方向。方向对重要的物理特性（如抗拉强度、刚度、抗撕裂性和冲击强度）有很大影响。 5.3 程序A中的数据对于确定取向度和方向、取向释放应力以及薄膜在给定温度下可以施加的最大力最为有用。 5.4 由于在实际应用中，薄膜很少（如果有的话）受到完全约束，因此程序B中的数据对于估计待包装物品实际将受到的力和预测包装物品的外观非常有用。 5.5 收缩张力随温度变化的表征，以及由此确定的取向释放应力及其相应温度，通常仅针对特定制造工艺的特定厚度材料进行。 出于产品开发目的，应根据被测材料的规范进行质量控制和符合性测定。相关ASTM材料规范中涵盖的任何试样制备、调节、尺寸或测试参数，或其组合，应优先于本试验方法中提及的。如果没有相关的ASTM材料规范，则默认条件适用。分类系统表1 D4000 列出了当前存在的ASTM材料规范。

1.1 This test method covers the determination of the shrink tension and related characteristics, that is, shrink force and orientation release stress, of heat-shrinkable plastic film and sheeting of less than 1.0 mm (0.04 in.) thickness. Two procedures are described that permit the measurement of shrink forces at predetermined temperatures. They are as follows: 1.1.1 Procedure A is designed to measure the maximum force exerted by a specimen that is totally restrained from shrinking as it is heated rapidly to a specific temperature. 1.1.2 Procedure B is designed to measure the maximum force exerted by a specimen that is permitted to shrink a predetermined amount prior to restraint while being heated rapidly to a specific temperature. 1.2 Orientation release stress can be determined from the data obtained using Procedure A. 1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Note 1: Film has been arbitrarily defined as sheeting having nominal thickness not greater than 0.25 µm (0.010 in.). Note 2: There is no known ISO equivalent to this test method. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 As a result of the manufacturing process, internal stresses are locked into the film and these can be released by heating. Note 3: For any given type of film or sheeting, the temperatures at which shrinkage will begin are related to processing techniques employed to manufacture the film and also may be related to a phase transition in the base resin. 5.2 Shrink tension affects the appearance and performance of a film in a shrink-packaging application. It is also used to determine the degree and direction of orientation. The orientation exerts a great influence upon important physical characteristics such as tensile strength, stiffness, tear resistance, and impact strength. 5.3 Data from Procedure A are most useful for determining the degree and direction of orientation, orientation release stress, and the maximum force that the film can exert at a given temperature. 5.4 Since, in actual applications, film is seldom, if ever, totally restrained, data from Procedure B are useful in estimating the force an item to be packaged will actually receive and in predicting the appearance of packaged items. 5.5 The characterization of shrink tension as a function of temperature, and the resultant determination of orientation release stress and its corresponding temperature, is usually carried out only for a particular material of specified thickness for a defined fabrication process. For product development purposes, quality control and determination of conformity be made to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or combination thereof, covered in the relevant ASTM material specification shall take precedence over those mentioned in this test method. If there are no relevant ASTM material specifications, then the default conditions apply. Table 1 of Classification Systems D4000 lists the ASTM material specifications that currently exist.