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Infrared spectroscopic studies on polyethylene, 4. The examination of drawn specimens of varying stress crack resistance

1976; Wiley; Volume: 177; Issue: 2 Linguagem: Inglês

10.1002/macp.1976.021770215

0025-116X

Margaret McRae, W. F. Maddams,

Polymer Nanocomposites and Properties

Abstract Infrared spectra, with both unpolarised and polarised radiation, have been obtained for a series of Phillips type high density polyethylenes of varying stress crack resistance. They were examined after cold drawing, by neck propagation, under standard conditions, and the presence of uniaxial orientation was confirmed by X‐ray pole figure measurements. Intensity measurements with unpolarised radiation on the bands at 1080, 1352, and 1894 cm −1 showed that with samples of bad stress crack resistance both the folds and the tie chains increase in concentration at the expense of the regularly folded chains in crystalline regions, whereas only the tie chains increase with samples having good stress crack resistance. Dichroic measurements on nine bands, the majority of them characteristic for methylene groups in gauche and trans conformations in amorphous regions, show that there is no marked degree of orientation of the chain folds or tie chains with samples of good stress crack resistance. However, there is significant orientation, particularly of the tie chains, for samples with poor stress crack resistance.