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Small‐angle neutron scattering functions from semicrystalline polymers
Author(s) -
Yoon D. Y.
Publication year - 1978
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889878013801
Subject(s) - crystallinity , crystallite , polyethylene , materials science , scattering , polymer , neutron scattering , small angle neutron scattering , crystallography , deuterium , composite material , optics , chemistry , physics , atomic physics , metallurgy
The angular dependence of the intensity of neutron scattering by deuterated polymers dispersed in the protonated host in the semicrystalline state has been computed over the scattering range 0 < μ < 0.2 Å, where μ = (4 π / λ ) sin ( θ /2), for various morphologies that differ according to the mode of chain re‐entry into the crystalline lamellae. Calculations have been carried out for melt‐crystallized polyethylene and solution‐grown polyethylene crystals of varying crystallite sizes and degrees of crystallinity. The scattering functions in the range 0.03 < μ < 0.15 Å −1 are little affected by changes in crystallite sizes and crystallinities, but vary strongly with the tendency for adjacent re‐entry and differ in magnitude and profile for the regularly folded morphology and the "switchboard' model. It was found that only the latter approximates the available experimental results. For melt‐crystallized polyethylene optimum agreement with available experimental results is achieved by a statistical model in which the chain preferentially re‐enters the crystalline layer at sites well removed from the site of emergence with a probability of about 0.7. For solution‐grown polyethylene crystals, the model of nearby (but not regularly folded) re‐entry gives good agreement with the results of Sadler & Keller [ Macromolecules (1977), 10 , 1128–1140].