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Polyacrylonitrile (PAN)/zinc oxide (ZnO) nanocomposites were prepared by solution mixing in dimethylacetamide, followed by film casting, and their physical properties were investigated. The heating scan of differential scanning calorimetry displayed only a single crystallization peak (Tc) without a melting peak, regardless of the presence of ZnO. The incorporation of ZnO nanoparticles decreased Tc by 13°C, and increased the heat of crystallization by 18%. Further, it greatly improved the thermal stability of PAN, even at the ZnO content as low as 0.1 wt %. The nanocomposites showed the UV transmittance peak at 365 nm, whose intensity was increased as ZnO content was increased. The presence of ZnO did not produce new peak nor shift the peaks with respect to PAN in wide angle X‐ray diffraction pattern. Introduction of a small amount of ZnO nanoparticles did not have notable effect on the tensile properties. However, 5 wt % loading of the nanoparticles increased the tensile modulus of PAN by 14.5% and decreased elongation at break dramatically. PAN nanocomposites with 5 wt % ZnO did not show any plateau region in stress–strain curve. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1854–1858, 2006

Effects of ferrite nanoparticles (0.1–20 wt %) on the rheological and other physical properties of nylon‐66 were investigated. The presence of ferrite nanoparticles less than 1 wt % increased the crystallization temperature (Tc) by 4.2 °C with ferrite content, but further addition decreased Tc. The onset temperature of degradation was increased by 7.3 °C at only 0.1 wt % loading of ferrite, after which the thermal stability of nylon‐66 was decreased with ferrite content. The incorporation of ferrite nanoparticles more than 5 wt % increased the dynamic viscosity (η′) with the loading level. Further, it produced notably shear thickening behavior in the low frequency, after which high degree of shear thinning was followed with ferrite content. In the Cole–Cole plot, the nanocomposites with ferrite lower than 5 wt % presented a single master curve, while further addition gave rise to a deviation from the curve. The relaxation time (λ) was increased with ferrite content and the difference of λ between nylon‐66 and its nanocomposite was greater at lower frequency. The tensile strength was a little increased up to 1 wt % loading, after which it was decreased with increasing the loading level. In addition, the introduction of the nanoparticles increased tensile modulus and decreased the ductility with ferrite content. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 371–377, 2006

Three different modes of rheological properties were measured on 11 and 13 wt % solutions of cellulose in N-methyl morpholine N-oxide (NMMO) monohydrate, in which concentration range lyocell fibers of much reduced fibrillation are preferably produced. The dynamic rheological responses revealed that the Cox–Merz rule did not hold for these cellulose solutions. Both cellulose solutions showed a shear thinning behavior over the shear rate measured at 85, 95, 105, and 115°C. However, 13 wt % solution gave rise to yield behavior at 85ºC. The power law index ranged from 0.36 to 0.58. First normal stress difference (N1) was increased with lowering temperature and with increasing concentration as expected. Plotting N1 vs shear stress (τω) gave almost a master curve independent of temperature and concentration, whose slope was about 0.93 for both cellulose solutions over the shear rate range observed (τω > 500 Pa). In addition, the cellulose solutions gave high values of recoverable shear strain (SR), ranging from 60 to 100. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 216–222, 2002