2826
Macromolecules 1994,27, 2826-2836
Proton Spin Diffusion Studies of Polymer Blends Having Modest Monomer Size. 2. Blends of Cellulose with either Poly(acrylonitri1e) or Poly(4-vinylpyridine) D. L. VanderHart,’v+ R. St. John Manley,t and J. D. Barnes? Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Pulp and Paper Research Centre and Department of Chemistry, McGill University, 3420 University Street, Montreal, Quebec, Canada H3A 2A7 Received September 29, 1993”
ABSTRACT: Blends of cellulose (CELL) with either poly(4-vinylpyridine) (P4VPy) or poly(acrylonitri1e) (PAN) have been examined by solid-state proton NMR. Multiple-pulse techniques combined with the phenomenologyof spin diffusionallow one to obtain information about average domain size along the thinnest dimension of the domains. In addition, one can obtain information about the stoichiometry of the phases. CELL/P4VPyblends were examined over a composition range from 30 to 70% CELL; CELL/PAN blends spanned a composition range from 32 to 88% CELL. It was found that average overall repeat distances for the CELLIP4VPyblends were in the 8-12-nm range, while for the CELL/PAN blends the range was ca. 16-24 nm. As a function of overall composition, there were no sudden changes in dimensions or, by implication, in miscibility. As to stoichiometry, very little mixing took place; typically
