1.1 本试验方法包括测定两个有效数字的塑料木材和塑料木材形状的线性热膨胀系数。通过使用卡尺在三个离散温度下进行测量来确定。在试验温度和施加的应力下，塑料木材应具有可忽略的蠕变或弹性应变率，或两者兼有，只要这些特性会显著影响测量的准确性。 1.1.1 本试验方法详细说明了塑料木材和“制造”形状的塑料木材的线性热膨胀系数的测定。因此，这是一种用于评估塑料木材或形状作为产品的性能的测试方法，而不是材料性能测试方法。 1.2 塑料木材和形状的热膨胀由可逆成分组成，其上可能叠加由于含水量变化、固化、增塑剂或溶剂损失、应力释放、相变、空隙、夹杂物和其他因素引起的长度变化。本试验方法旨在尽可能排除非线性因素的情况下确定线性热膨胀系数。一般来说，不可能完全排除这些因素的影响。因此，可以期望试验方法能够给出合理的近似值，但不一定能够精确确定热膨胀的线性系数。 1.3 塑料木材和塑料木材形状目前主要由再生塑料制成，其中产品横截面不均匀。然而，本试验方法也可能适用于由原始树脂或其他塑料复合材料制成的类似制造塑料产品。 1.4 以英寸-磅为单位的数值应视为标准值。括号中给出的国际单位仅供参考。 1.5 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: 没有已知的ISO等效于本标准。 1.6 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 温度之间的线性热膨胀系数α T 1. 和 T 2. 对于长度为 L 0 在参考温度下，由以下等式得出: 哪里 L 1. 和 L 2. 是温度下的试样长度 T 1. 和 T 2. 分别地 因此，α是通过将单位长度的线性膨胀除以温度变化得到的。 5.2 大多数塑料的性质和使用塑料木材和塑料木材形状的建筑应用，使–30至140°F（-34.4至60°C）成为线性热膨胀测量的实际温度范围。如果在该温度范围外进行测试，或者在该温度范围内不知道特定塑料的线性热膨胀特性，则应特别注意 1.2 也可能通过热机械分析进行特殊的初步调查，例如实践中规定的情况 D4065 对于过渡温度的位置，将需要，以避免过度误差。如果位于此类过渡点，则应确定低于和高于该过渡点的温度范围的单独膨胀系数。出于规范和比较目的（前提是该范围内不存在过渡），应使用-30至140°F（-34.4至60°C）的范围。（供参考，塑料木材产品中使用的典型树脂的玻璃化转变和熔点温度见 附录X2 本试验方法）

1.1 This test method covers the determination of the coefficient of linear thermal expansion for plastic lumber and plastic lumber shapes to two significant figures. The determination is made by taking measurements with a caliper at three discrete temperatures. At the test temperatures and under the stresses imposed, the plastic lumber shall have a negligible creep or elastic strain rate, or both, insofar as these properties would significantly affect the accuracy of the measurements. 1.1.1 This test method details the determination of the linear coefficient of thermal expansion of plastic lumber and plastic lumber shapes in their “as manufactured” form. As such, this is a test method for evaluating the properties of plastic lumber or shapes as a product and not a material property test method. 1.2 The thermal expansion of plastic lumber and shapes is composed of a reversible component on which it is possible to superimpose changes in length due to changes in moisture content, curing, loss of plasticizer or solvents, release of stresses, phase changes, voids, inclusions, and other factors. This test method is intended to determine the coefficient of linear thermal expansion under the exclusion of non-linear factors as far as possible. In general, it will not be possible to exclude the effect of these factors completely. For this reason, the test method can be expected to give a reasonable approximation but not necessarily precise determination of the linear coefficient of thermal expansion. 1.3 Plastic lumber and plastic lumber shapes are currently made predominately with recycled plastics where the product is non-homogeneous in the cross-section. However, it is possible that this test method will also be applicable to similar manufactured plastic products made from virgin resins or other plastic composite materials. 1.4 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only. 1.5 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: There is no known ISO equivalent to this standard. 1.6 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 The coefficient of linear thermal expansion, α, between temperatures T 1 and T 2 for a specimen whose length is L 0 at the reference temperature, is given by the following equation: Where L 1 and L 2 are the specimen lengths at temperatures T 1 and T 2 , respectively. α is, therefore, obtained by dividing the linear expansion per unit length by the change in temperature. 5.2 The nature of most plastics and the construction applications for which plastic lumber and plastic lumber shapes are used, make –30 to 140°F (–34.4 to 60°C) a practical temperature range for linear thermal expansion measurements. Where testing outside of this temperature range or when linear thermal expansion characteristics of a particular plastic are not known through this temperature range, particular attention shall be paid to the factors mentioned in 1.2 and it is possible that special preliminary investigations by thermo-mechanical analysis, such as what is prescribed in Practice D4065 for the location of transition temperatures, will be required, in order to avoid excessive error. If such a transition point is located, a separate coefficient of expansion for a temperature range below and above the transition point shall be determined. For specification and comparison purposes (provided it is known that no transition exists in this range), the range from –30 to 140°F (–34.4 to 60°C) shall be used. (For reference, glass transition and melting point temperatures of typical resins used in plastic lumber products are given in Appendix X2 of this test method.)