Sources of error in bulk polymer densities determined by the gradient column technique

Abstract

Sources of error in the determination of the density of bulk‐crystallized polyethylene in gradient columns have been reconsidered. Preferential absorption of any one column liquid can lead to gross differences between the apparent polymer densities as determined in different columns. It is therefore important to select column liquids which have about the same swelling power for the polymer. Samples of very high specific surface should be avoided, though the threshold for significant errors of this kind is unlikely to be crossed in practice. Finally, water should not be used as a column liquid in connection with polyethylene measurements because water‐rich mixtures may not wet the polymer completely. The principles emerging from this work are likely to be of general application.

Ultradrawing of High Molecular Weight Polyethylene Films Produced by Gelation/Crystallization from Solution: Effect of the Number of Entanglements

“…According to Blackadder et a/. 8 and Bhateja, 9 the mixture of chlorobenzene and toluene was used as a good medium to avoid a density differential between the imbibed and the ambient liquids around the specimen. Therefore chlorobenzene-toluene was used as the medium in this experiment to prevent the preferential absorption.…”

Recent Advances in the Liquid-Phase Syntheses of Inorganic Nanoparticles

“…The theory of coprecipitation is not a trivial subject. Numerous books , and review articles − cover the topic much more thoroughly than the discussion presented here. As a brief overview, coprecipitation reactions tend to exhibit the following characteristics: (i) The products of precipitation reactions are generally sparingly soluble species formed under conditions of high supersaturation.…”

Dynamic mechanical behavior of ultradrawn polyethylene films produced by gelation/crystallization from solution

“…We doubt whether xylene-carbon tetrachloride is suitable as a medium to measure the density of polyethylene, because of preferential absorption by polyethylene of one liquid. According to Blackadder et al [19] and Bhateja [20], the mixture of chlorobenzene and toluene was used as a good medium to avoid a density differential between the imbibed and the ambient liquids around the specimen. Therefore chlorobenzene-toluene was also used as the medium in this experiment to prevent preferential absorption.…”