Radiation-induced crosslinking: III. Effect on the crystalline and amorphous density fluctuations of polyethylene |
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| Authors: | C J Chen G S Y Yeh |
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| Institution: | (1) Present address: Departments of Chemical Engineering and Metallurgical Engineering, University of Michigan, 48107 Ann Arbor, Michigan, USA;(2) Macromolecular Research Center, University of Michigan, 48107 Ann Arbor, Michigan, USA |
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| Abstract: | Small-angle x-ray scattering (SAXS) was used to determine density fluctuation in radiation-induced crosslinked polyethylene of varying degrees of crystallinity. Density fluctuation FL decreases with increasing crystallinity, while it increases linearly with increasing radiation dose or degree of crosslinking. By means of extrapolation, density fluctuations in the crystalline and the amorphous phasesFL
c
andFL
a
were obtained. At a given dose,FL
a
is greater thanFL
c
. The increase inFL
a
with radiation is found to be much greater than that ofFL
c
compared with the initial values at 0 Mrad,FL
c
showing only a negligible increase event at 312 Mrad. The present findings suggest that crosslinks are not introduced within the crystalline phase; they take place primarily in the noncrystalline phase, in agreement with the conclusions reached previously on the basis of changes in crystalline and amorphous densities in irradiated polyethylene.Dedicated to Prof. Dr. W. Pechhold on the occasion of his 60th birthday |
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| Keywords: | Crosslinking radiation polyethylene density crystallinity phasedensities densityfluctuation phasedensityfluctuations Crosslink locations and mechanisms defects lateral grainboundaries |
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