The texture of melt crystallised polythene as revealed by selective oxidation

Abstract

It has been discovered that when fuming nitric acid oxidises bulk samples of polythene crystallised from the melt, preferential attack on the links between the lamellar crystals occurs with the consequent release of fragments of these crystals. The reaction is not confined to the surface of samples and lamellar crystals can be separated from relatively massive specimens for further study.Selected area electron diffraction results are presented to show that the molecular chains are oriented approximately perpendicular to the plane of the lamellae and that the sheets are substantially single crystals.The results of an examination, by a variety of physical methods, of the lamellar crystals and reaction products from samples with different thermal histories treated for different times are given. Analysis of the results confirms that the attack occurs preferentially at the available amorphous regions, which in the case of the linear polymer are almost exclusively located between the lamellar crystals.

Structure of Polymer Single Crystals

“…For PE, early experiments involved degradation with nitric acid (Palmer and Cobbold, 1964). The molecular weight of the residual segments which ultimately were reduced to a somewhat shortened stem length was followed by GPC (Blundell et al, 1966 b).…”

Abbau von aus der schmelze kristallisiertem polyäthylen durch salpetersäure

“…(2) zur Bestimmung von be benutzen, jedoch ist dies wesentlich ungenauer als nach G1. (1). Neben der Unsicherheit der Bestimmung von 1 aus dem Molekulargewicht der abgebauten Proben fallen die experimentellen Fehler von Rontgen-Kristallinitat ( 1 2 yo) (die sowohl in AHK als auch in 1 eingehen) und Schmelzwarme 4 H (h1 cal/g) sehr stark ins Gewicht.…”

“…C)lO. ), man erkennt jedoch trotzdem in Abb 1,. daB T, durch die HN03-Behandlung kaum beeinfluat wird.…”

Hardness of nitric acid treated polyethylene followed by recrystallization

“…The changes in microstructure and the detailed mechanism of fuming nitric attack to bulk K 153 polyethylene has been extensively discussed in the past [5][6][7][8][9][10][11]. The major issues may be summarized as follows: fuming nitric acid exposure, first, removes the disordered domains selectively inducing a weight-loss of material (10-70 %) depending on crystallinity.…”