SynopsisMacromolecules at the surface of a polymeric solid have considerable mobility, and the specific arrangement of functional groups of macromolecules at the surface is dictated by the environmental conditions in which the surface is placed. Consequently, the change of environmental conditions, such as immersion in water or placement in a biological surrounding, could cause a cosiderable degree of change in the surface characteristics of a polymer from those evaluated in the laboratory against ambient air. The mobile nature of a polymer surface can be investigated by surface-implanting fluorine-containing moieties, mainly -CF,, by the plasma implantation technique and following the disappearance and reappearance of fluorine atoms on the surface. The disappearance rates (based on the immersion time in water at room temperature) of ESCA Fls signals, the decay rates of (advancing) contact angle of water, and the recovery of these values on heat treatment of water-immersed samples were measured as a function of crystallinity of polymer samples (at three levels of crystallinity) for poly(ethy1ene terephthalate) and nylon 6.

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We investigated the correlation between crystallinity and plasma susceptibility for PET and nylon 66 fibers. Plasma susceptibility is measured by the weight loss observed when fibers of varying crystallinity are exposed to air plasma. We varied the crystallinity of samples by annealing fibers at different temperatures. Plasma susceptibility and dyeability as a function of the crystallinity of fibers showed a striking resemblance: both decreased with increasing crystallinity up to a threshold crystallinity, above which there were appreciable increases. Plasma susceptibilities of these fibers, under the conditions used in this investigation, are believed to be proportional to the dyeable non-crystalline region, but not to the total noncrystalline phase of fibers.

The origins of the thermal and mechanical properties of chitosan and poly(vinyl alcohol) (PVA) with inter-and intra-hydrogen bonds were investigated systematically by using X-ray, DSC, positron annihilation and viscoelastic measurements. Based on their individual properties, the characteristics of the blend films were estimated in relation to their morphology and mechanical properties as a function of chitosan content. The characteristics of the blend films were also analyzed in terms of the deviation from a simple additive rule of chitosan and PVA content. These results suggested that the miscibility of chitosan and PVA could be ensured by entanglement of the amorphous chain segments of chitosan and PVA. Further detailed analysis revealed that the chitosan content on the film surface is higher than that of the admixture content of chitosan after elongation, although the chitosan and PVA chains were crystallized independently. The elongation could be achieved for the blend films whose PVA content was higher than 50% and the drawn blend films were transparent. Thus, it may be expected that sufficiently entangled meshes formed between chitosan and PVA amorphous chains within the film, the PVA content being higher than 50%, were maintained under the elongation process.