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A Study on the Degree of Amidoximation of Polyacrylonitrile Fibers and Its Effect on Their Capacity to Adsorb Uranyl Ions
journal contribution
posted on 2015-04-01, 00:00 authored by Huanhuan Zhao, Xiyan Liu, Ming Yu, Ziqiang Wang, Bowu Zhang, Hongjuan Ma, Min Wang, Jingye LiAmidoximation
of polyacrylonitrile (PAN) fibers was studied by
reacting them with hydroxylamine. The chemical structure, mechanical
intensity, and morphologies of PAN and amidoximated PAN (AO-PAN) fibers
were evaluated by Fourier transform infrared spectroscopy, tensile
tests, dynamic mechanical analysis, and scanning electron microscopy,
respectively. A higher degree of amidoximation resulted in a higher
conversion ratio (CR) of the nitrile group and a higher density of
the amidoxime group, while also reducing the mechanical intensity
of the fibers. During amidoximation, a hydrogel layer formed on the
fiber surface by bonding with H2O molecules, increasing
the diameter of the AO-PAN fibers. The layer thickness increased as
the CR of the AO-PAN fibers’ nitrile group was increased. The
hydrogel layer decreased the adsorption capability by hindering the
diffusion of uranyl ions to the interior of the AO-PAN fibers. Therefore,
a CR of about 10.8% would provide an appropriate balance between the
mechanical properties and the adsorption capability.