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The effects of isotactic polypropylene (PP) on the rheological properties of ultra high molecular weight polyethylene (UHMWPE) have been measured in a broad range of composition (0, 5, 15, 30 wt% PP) at various temperatures (110, 130, and 150°C) and a specific gel concentration of 6 wt%. The result showed that the viscosity of the UHMWPE significantly decreased with the addition and increasing amount of PP. Regardless of temperature, the viscosity function followed the power‐law behavior. Copyright © 2009 John Wiley & Sons, Ltd.

This article describes the physical properties of lyocell fibers spun from an isotropic cellulose spinning dope in N-methyl morpholine N-oxide (NMMO) monohydrate (IPS lyocell fibers). Wide angle x-ray diffraction (wAxD) experiments on the crimped fibers exhibit little difference in the crystal structure of IPS and Tencel lyocell fibers: both fibers reveal a cellulose II structure. However, the IPS lyocell fibers have a lower tensile modulus than Tencel by about 12.5%, although they have a similar tensile strength. Wetting and subsequent drying shift the loss tangent values higher, which is more remarkable for the IPS lyocell fibers dried under tension. Further, the IPS lyocell fibers dried under tension have a sharper α-transition peak than the fibers dried without tension. The IPS lyocell fibers exhibit excellent wet tensile strength: 90% of tensile strength is retained after wetting twice in distilled water. In addition, the IPS lyocell fibers show good chemical stability to acids and alkalis, except for an extremely strong alkali—pH 14. Mercerization of the IPS lyocell fibers in the buffer solution of pH 14 notably decreases the tensile modulus but increases elongation.

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The ultra high molecular weight polyethylene (UHMWPE)/organoclay nanocomposites were prepared in decalin with various organoclay contents (0, 1, 2, 3, and 5 pphr). Transmission electron micrographic images and X-ray diffraction results showed that the organoclay was exfoliated and well dispersed in UHMWPE matrix. The rheological properties were measured at various temperatures (110, 130, and 150 C) in a broad range of shear rate (10 À1 -10 2 ) at a gel concentration of 6 wt %. The result showed that the viscosity increased with the addition and increasing organoclay content. Thermal stability (thermogravimetric analysis) and crystallinity (differential scanning calorimeter) of UHMWPE increased with increasing organoclay content implying that the organoclay functioned as barrier and nucleating agent. V