BS EN ISO 16014-5:2019

What is ISO 16014-5 - Determination of average molecular weight with SEC-LS about?

ISO 16014-5 is the fifth part of the multi-series ISO 16014. ISO 16014-5 specifies a general method for determining the average molecular weight and the molecular weight distribution of polymers using SEC-LS, i.e., size-exclusion chromatography coupled with light-scattering detection. The average molecular weight and the molecular weight distribution are calculated from molecular weight data and weight concentrations determined continuously with elution time. The molecular weight at each elution time is determined absolutely by combining a light-scattering detector with a concentration-sensitive detector. Therefore, SEC-LS is classified as an absolute method.

ISO 16014-5 method applies to linear homopolymers and nonlinear homopolymers such as branched, star-shaped, comb-like, stereo-regular, and stereo-irregular polymers. It can also be applied to heterophasic copolymers whose molecular composition cannot vary. However, SEC-LS is not applicable to block, graft, or heterophasic copolymers whose molecular composition can vary. And the methods apply to molecular weights ranging from that of the monomer to 3 000 000 but are not intended for samples that contain > 30 % of components having a molecular weight < 1 000.

Who is ISO 16014-5 - Determination of average molecular weight with SEC-LS for?

ISO 16014-5 on the determination of average molecular weight with SEC-LS is useful for:

• Manufacturers of polymers products such as grocery bags, soda and water bottles, textile fibers, phones, computers, food packaging, auto parts, and toys
• Plastic testing laboratories

Why should you use ISO 16014-5 - Determination of average molecular weight with SEC-LS?

The average molecular weight (M_w) measuring system includes the mass of individual chains, which contributes to the overall molecular weight of the polymer. It is since bigger molecules contain more mass than smaller molecules. Thus larger the size of the molecule more its contribution to the molecular weight average.

ISO 16014-5 specifies the methods to determine the average molecular weight of plastic because the molecular weight of a polymer is directly related to its properties. As the molecular weight increases, mechanical properties generally increase as every polymer has an ideal molecular weight at which the balance of different properties (such as processability, strength, brittleness, etc.) is optimized.

Determination of average molecular weights of plastic using size-exclusion chromatography linked with the Light-scattering method (SEC-LS) can provide information about the polymer molecular weight distribution and provide information on the molecular architecture and size when in solution. 

What’s changed since the last update?

BS EN ISO 16014-5:2019 supersedes ISO 16014‑5:2012. BS EN ISO 16014-5:2019 includes some technical changes with respect to ISO 16014‑5:2012. These include:

• Publication dates of references have been removed
• Molecular mass has been changed to molecular weight according to the IUPAC rule.