Stress relaxation of polyisoprene–laponite nanocomposites monitored by magic angle spinning ¹H NMR and optical microscopy

Abstract In order to illustrate the capacity of nuclear magnetic resonance (NMR) to monitor compression‐induced changes in the morphology of nanocomposites, solid‐state NMR results were directly contrasted with optical microscopy. Increases in the interfacial area of Laponite clay in cis 1,4‐polyisoprene composites were monitored during uniaxial compression. Interaction of the Co⁺² in the clay galleries with the polymer decreases the polymer's ¹H spin‐lattice relaxation time constant (T₁). The composite showed a decrease in T₁ time constant with increasing compressive strain. This behavior is consistent with an increase in interfacial area of the aggregate as it breaks apart. Increases in interfacial area of the aggregate were confirmed with optical micrographs. POLYM. COMPOS., 26:799–805, 2005. © 2005 Society of Plastics Engineers