Characterization of polyamides 6, 11, and 12. Determination of molecular weight by size exclusion chromatography (IUPAC Technical Report)

Abstract

This report presents the results from IUPAC Working Party IV.2.2 of the global trial within the framework of IUPAC Commission IV.2, “Characterization of Commercial Polymers”. The results were compared on the basis of molecular weight obtained by size exclusion chromatography (SEC)using different techniques practiced in participating laboratories, the majority of which were materials suppliers. The practical methodologies used different solvents for the polymers, in particular, benzyl alcohol, 1,1,1,3,3,3 hexafluoropropan-2-ol and tetrahydrofuran; the latter solvent was used after chemical modification of the polyamides, in general with trifluoroacetic anhydride. Eight laboratories participated in the trial. The repeatability for molecular weight in each laboratory was good, whatever technique was used, the relative standard deviation averaged over all laboratories being around 3%. The deviations in distribution of molecular weights with different experimental methodologies were broader, but were reasonably good despite the diversity of methods. The differences in the distribution correspond to a confidence interval of about 30% in molecular weight.

Size exclusion chromatography – A blessing and a curse of science and technology of synthetic polymers

“…The least scattered M ‐values were obtained in the industrial laboratories, where evidently the skilled operators carefully performed the measurements. Better data accuracy was obtained for the “difficult” samples, polyamides 110, poly(olefins) and for oligomeric polyepoxides 111 than for the “unproblematic” poly(dimethyl siloxane)s and even for the most “simple” polymer, polystyrene – likely because only experts measured the former samples. It is evident, that the world‐wide standardization of both measurement and data processing are badly needed in SEC.…”

“…The recent round robin tests organized under auspices of IUPAC 109–112 have brought about alarming results. Several commercial samples of oligomers and mostly linear (high)polymers were sent to participating laboratories.…”

Thermally induced dissolution/precipitation – A simple approach for the preparation of macroporous monoliths from linear aliphatic polyamides

“…Polyamides are potential candidates for the approach because of their UCST behavior in several solvents at practically reachable temperature [22,23], excellent mechanical rigidity, and the availability of a variety of homo-and co-polymers spanning a wide hydrophobicity/ hydrophilicity range. Numerous methods for modification of polyamides are also well documented [24 -30].…”

“…Although modest toxicity and cost were favorable factors, the primary reason for selecting benzyl alcohol (BA) was that it offers UCST's well-above ambient temperature for many aliphatic polyamides. Precipitation by UCST traversal can therefore be effectuated without super-cooling [23]. FRG) and the methanol used to remove BA by Soxhlet extraction was of "pure grade" from Prolabo (Paris, France).…”

Toughened and hydrophobically modified polyamide 11 copolymers with dimer acids derived from waste vegetable oil

“…After the reaction with the anhydride, it is soluble in THF as the strong hydrogen bonds are broken by trifluoroacetylation. This method is reliable with high conversion and reproducibility . Homo‐PA11 was synthesized with a reasonable molar mass of 38 kg mol −1 and dispersity (Ð) of 2.3, similar to the literature and commercial products .…”