GSO ISO 16014-2:2014
塑料 尺寸排阻色谱法测定各种分子的平均分子量和分子量分布 第2部分：通用滴定法

Plastics -- Determination of average molecular mass and molecular mass distribution of polymers using size-exclusion chromatography -- Part 2: Universal calibration method

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标准号

GSO ISO 16014-2:2014

发布

2014年

发布单位

GSO

当前最新

GSO ISO 16014-2:2014

 

 

适用范围

This part of ISO 16014 specifies a method for determining the average molecular mass and the molecular mass distribution of polymers using size-exclusion chromatography (SEC). The average molecular mass and the molecular mass distribution are calculated using a universal calibration curve instead of the conventional calibration curve. A list of documents related to this part of ISO 16014 is given in the Bibliography. NOTE The concept of the universal calibration method is based on a relationship by which the retention time in SEC depends on the size of the polymer molecule (the hydrodynamic volume) or on the product of the intrinsic viscosity [η] and the molecular mass M. Many polymers classified as random-coil polymers (regardless of their chemical structure, degree of branching, composition or tacticity) have been experimentally confirmed as following this relationship. The universal calibration curve is prepared by plotting the logarithm of [η]M against the elution time t or elution volume V using polymer standards such as polystyrene with narrow molecular mass distributions. The molecular mass Mi of an unknown polymer sample can then be calculated from the value of [η]M at each retention time using the universal calibration curve and [η] or K and a in the Mark-Houwink-Sakurada equation ([η] = KMa → [η]M = KMa+1), where K is a constant and a is an exponent depending on the experimental conditions. Therefore this test method is classified as a relative method as described in ISO 16014-1, but the average molecular masses and molecular mass distributions calculated by the method are equal to, or nearly equal to, the absolute values.

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