Composition dependence of the interaction parameter in isotopic polymer blends

Journal Article · Mon May 09 00:00:00 EDT 1994 · Macromolecules; (United States)

DOI:https://doi.org/10.1021/ma00088a029· OSTI ID:7288792

Londono, J D; Narten, A H; Wignall, G D ^[1]; Honnell, K G; Hsieh, E T; Johnson, T W ^[2]; Bates, F S ^[3]

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1. Oak Ridge National Lab., TN (United States)
2. Phillips Petroleum Co., Bartlesville, OK (United States). Research and Development
3. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering

Isotopic polymer mixtures lack the structural asymmetries and specific interactions encountered in blends of chemically distinct species. In this respect, they form ideal model systems for exploring the limitations of the widely-used Flory-Huggins (FH) lattice model and for testing and improving new theories of polymer thermodynamics. The FH interaction parameter between deuterium-labeled and unlabeled segments of the same species ([sub [chi]HD]) should in principle be independent of concentration ([phi]), through previous small-angle neutron scattering (SANS) experiments have shown that it exhibits a minimum at [phi] [approximately] 0.5 for poly(vinylethylene) (PVE) and poly(ethylethylene) (PEE). The authors report new data on polyethylene (PE) as a function of molecular weight, temperature (T), and [phi], which show qualitatively similar behavior. However, measurements on [sub [chi]HD]([phi]) for polystyrene (PS) show a maximum at [phi] [approximately]0.5, in contrast to PVE, PEE, and PE. Reproducing the concentration dependence of [phi] in different model isotopic systems should serve as a sensitive test of the way in which theories of polymer thermodynamics can account for the details of the local packing and also the effects of noncombinatorial entropy, which appear to be the main cause of the variation of [sub [chi]HD]([phi]) for PE. These data also serve to quantify the effects of isotopic substitution in SANS experiments on polyolefin blends and thus lay the ground work for definitive studies of the compatibility of branched and linear polyethylenes.

• OSTI ID: 7288792
• Journal Information: Macromolecules; (United States), Vol. 27:10; ISSN 0024-9297
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
POLYETHYLENES
MORPHOLOGY
THERMODYNAMIC PROPERTIES
POLYSTYRENE
EXPERIMENTAL DATA
MATHEMATICAL MODELS
DATA
INFORMATION
MATERIALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHYSICAL PROPERTIES
PLASTICS
POLYMERS
POLYOLEFINS
POLYVINYLS
SYNTHETIC MATERIALS
360602* - Other Materials- Structure & Phase Studies
360606 - Other Materials- Physical Properties- (1992-)