Standards Development

Scope

This document specifies a method for the determination of the tetrahydrofuran (THF) content in butanediol-based polyesters, produced through the copolymerization of butanediol and dicarboxylic acids, such as polybutylene succinate (PBS), polybutylene terephthalate (PBT), poly (butyleneadipateco-terephthalate) (PBAT), polybutylene adipate terephthalate (PBA), polyethylene naphthalate (PBN), polydiethylene glycol sebacate (PBSE) and polysebacic acid butyl terephthalate (PBSeT). This document is also applicable as a reference method for the determination of THF contents in the blend materials containing one or more polyesters mentioned above (such as PBT/PC (polycarbonate) blends).

Purpose

Butanediol-based polyesters, such as polybutylene succinate (PBS), polybutylene terephthalate (PBT), poly(butylene adipate-co-terephthalate) (PBAT), polybutylene adipate terephthalate (PBA), and polyethylene naphthalate (PBN), are biodegradable plastics with excellent performance. They are widely used in various fields, including packaging, daily necessities, agriculture, textiles, and biomaterials. These polyesters are produced through the copolymerization of butanediol with dicarboxylic acids. During this process, tetrahydrofuran (THF), a by-product, remains in the free state within the polymer matrix.

THF has a pungent odor and is known to exhibit reproductive toxicity. It can also create vacancies in the polymer structure that affect subsequent deep processing, leading to a reduction in product quality. Currently, no standard method exists for measuring THF content in butanediol-based polyesters, thus necessitating the establishment of a reliable method for its determination.

As a trace volatile organic compound in plastics, THF is difficult to detect directly by conventional spectroscopy or chromatography. However, using headspace gas chromatography, THF can be vaporized by heating and then injected into the chromatograph for detection and analysis via headspace sampling. The low detection limit of this method enables effective quantification of THF content in butanediol-based polyesters.