1.1 本试验方法描述了测定重均分子量的试验程序 M w 聚合物的光散射。它适用于所有非离子均聚物（线性或支链），其完全溶解而不发生反应或降解以形成稳定溶液。共聚物和聚电解质不在其范围内。该程序还可以确定第二个维里系数， A. 2. ，这是聚合物-溶剂相互作用和旋转均方根半径的度量( s 2. ) 1/2 ，这是聚合物链尺寸的度量。 1.2 光散射的分子量范围在某种程度上取决于溶解聚合物分子的大小以及溶剂和聚合物的折射率。通常所述的范围为10000到10000000，通常通过适当的系统和使用特殊技术在任意方向上扩展。 1.2.1 分子量的下限是由于过量溶液在溶剂上的散射水平较低。 比折射增量d越大 n /d c （溶液和溶剂每单位浓度的折射率差），溶液散射水平越高，应以给定精度测定的分子量越低。 1.2.2 分子量的上限源于溶液散射的角度依赖性，这由分子大小决定。对于足够大的分子，必须在小散射角下进行测量，散射角最终超出所用光度计的范围。 1.3 以国际单位制表示的数值应视为标准值。 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: 没有已知的ISO等效于本标准。 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====== 4.1 重均分子量是聚合物的一个基本结构参数，它与块体材料的许多物理性质有关，例如其流变行为。此外，重量平均分子量的知识，以及渗透压法的数平均分子量的知识，提供了分子量分布宽度的有用测量方法。 4.2 重均分子量信息的其他重要用途包括与稀溶液或熔体粘度测量的相关性以及用于液体的分子量标准的校准- 排斥（凝胶渗透）色谱法。 4.3 在适当校准光散射光度计的情况下，光散射是一种绝对方法，因此适用于之前未合成或研究的非离子均聚物。

1.1 This test method describes the test procedures for determining the weight-average molecular weight M w of polymers by light scattering. It is applicable to all nonionic homopolymers (linear or branched) that dissolve completely without reaction or degradation to form stable solutions. Copolymers and polyelectrolytes are not within its scope. The procedure also allows the determination of the second virial coefficient, A 2 , which is a measure of polymer-solvent interactions, and the root-mean-square radius of gyration ( s 2 ) 1/2 , which is a measure of the dimensions of the polymer chain. 1.2 The molecular-weight range for light scattering is, to some extent, determined by the size of the dissolved polymer molecules and the refractive indices of solvent and polymer. A range frequently stated is 10,000 to 10,000,000, is often extended in either direction with suitable systems and by the use of special techniques. 1.2.1 The lower limit to molecular weight results from low levels of excess solution scattering over that of the solvent. The greater the specific refractive increment d n /d c (difference in refractive indices of solution and solvent per unit concentration), the greater the level of solution scattering and the lower the molecular weight that shall be determined with a given precision. 1.2.2 The upper limit to molecular weight results from the angular dependence of the solution scattering, which is determined by the molecular size. For sufficiently large molecules, measurements must be made at small scattering angles, which are ultimately outside the range of the photometer used. 1.3 The values stated in SI units are to be regarded as standard. 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: There is no known ISO equivalent to this standard. 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 ====== 4.1 The weight-average molecular weight is a fundamental structure parameter of polymers, which is related to many physical properties of the bulk material, such as its rheological behavior. In addition, knowledge of the weight-average molecular weight, together with knowledge of the number-average molecular weight from osmometry, provides a useful measure of the breadth of the molecular-weight distribution. 4.2 Other important uses of information on the weight-average molecular weight are correlation with dilute-solution or melt-viscosity measurements and calibration of molecular-weight standards for use in liquid-exclusion (gel-permeation) chromatography. 4.3 To the extent that the light-scattering photometer is appropriately calibrated, light scattering is an absolute method and is therefore be applied to nonionic homopolymers that have not previously been synthesized or studied.