The following papers are publications of NIST, an agency of the U.S. Government,
and by stature is not subject to copyright in the United States.
One can, thus, download those PDF's from NIST site, linking from this page.

13. Solid State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 2.
Measurement of Clay Dispersion, Crystal Stratification, and Stability of Organic Modifiers, 
D.L. VanderHart, Atsushi Asano, and J.W. Gilman,
Chemistry of Materials, 2001, 13(10), pp.3796-3809. [ PDF ]

12. Solid State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 1.
Crystallinity, Morphology, and the Direct Influence of Fe+3 on Nuclear Spins, 
D.L. VanderHart, Atsushi Asano, and J.W. Gilman,
Chemistry of Materials, 2001, 13(10), pp.3781-3795. [ PDF ]

11. NMR Measurements Related to Clay-Dispersion Quality and 
Organic-Modifier Stability in Nylon-6/Clay Nanocomposites, 
D.L. VanderHart, Atsushi Asano, and J.W. Gilman,
Macromolecules, 2001, 34(12), pp.3819-3822. [ PDF ]

10. Flame Retardant Mechanism of Silica Gel/Silica, 
T. Kashiwagi, J.W. Gilman, K.M. Butler, R.H. Harris, 
J.R. Shields, and Atsushi Asano
Fire and Materials, 2000, 24(6), pp.277-289. [ PDF ]