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Small‐angle neutron scattering study of poly(vinyl alcohol) gels during melting process
Author(s) -
Takahashi Nobuaki,
Kanaya Toshiji,
Nishida Koji,
Kaji Keisuke
Publication year - 2004
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.20818
Subject(s) - crystallite , vinyl alcohol , power law , materials science , exponent , small angle neutron scattering , neutron scattering , scattering , small angle scattering , melting point , deuterium , crystallography , polymer chemistry , analytical chemistry (journal) , chemistry , composite material , polymer , optics , physics , organic chemistry , mathematics , atomic physics , linguistics , statistics , philosophy
Small‐angle neutron scattering (SANS) measurements were performed on poly(vinyl alcohol) (PVA) gels in a mixture of deuterated dimethyl sulfoxide (DMSO‐d 6 ) and D 2 O with volume ratio of 60/40 to see the structure changes of the crosslinking points, which are crystallites, and of the gel network during the melting process. The observed SANS intensities were fitted to the Ornstein–Zernike (OZ) formula and a power law in scattering vector Q ranges from 0.01 to 0.035 and 0.05 to 0.1 Å −1 , respectively, to evaluate the correlation length ξ and the power law exponent n. It was found that the exponent n is 4 and the correlation length ξ is ∼ 150 Å below ≈70°C, suggesting that the crystallite surface is smooth and the average distance between the neighboring crystallites is ≈150Å. On the other hand, they begin to decrease >70°C. The decrease of n suggests that the surface of the crystallites becomes rougher with increasing temperature. As for the correlation length ξ, analyses in terms of distance distribution function suggested that the decrease of ξ is apparent, and the intercrystallite distance increases with temperature >70°C because the crystallites decrease in number because of melt. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 157–160, 2005