Hydrogen{endash}hydrogen intermolecular structure of polyethylene in the melt
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)
- Department of Materials Science and Engineering and Department of Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)
- Research and Development, Phillips Petroleum Company, Bartlesville, Oklahoma 74004 (United States)
- ISIS Science Division, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11-OQX (United Kingdom)
Three polyethylene samples, which differed in their degree of deuteration, were studied in neutron diffraction isotopic substitution (NDIS) experiments at 428 K. These results were complemented at small wavevectors by small angle neutron measurements. The intermolecular hydrogen{endash}hydrogen (HH) structure function, h{sub HH}(Q), was obtained without recourse to intramolecular structure models, as demonstrated in a prior report. The PE experimental results are compared to computer simulation results for the alkanes C100 at 509 K and C44 at 350, 400, and 450 K. The small temperature dependence of the HH intermolecular radial distribution functions, g{sub HH}(r) for C44 indicates that the differences observed between the PE, C100, and C44 (450 K) results are, for the most part, not due to just temperature differences. It is shown that the string model, an analytic result from an integral equation theory of polymers (PRISM), can account approximately for the overall shape of the g{sub HH}(r) functions, and that this overall shape is dependent on the radius of gyration of the molecule. Further analysis shows that there are two other contributions to g{sub HH}(r), both of which are independent of chain length to first order. The first is due to chain{endash}chain packing, and the second is due to local HH intermolecular correlations. These results are significant because they demonstrate that h{sub HH}(Q) is a useful function for studying intermolecular polymer structure, which has been shown to underpin phase behavior in polyolefin blends. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 336662
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 17 Vol. 110; ISSN 0021-9606; ISSN JCPSA6
- Country of Publication:
- United States
- Language:
- English
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