Time-resolved observation by transmission electron microscopy (TEM), viz., in situ TEM, of "same regions" in an oriented amorphous and in an unoriented amorphous i-PS thin films during isothermal crystallization was carried out to elucidate its oriented-crystallization and unoriented crystallization mechanisms, respectively. In situ TEM of an oriented i-PS thin film showed that edge-on lamellae grew perpendicularly to the flowing direction to which the c-axis is parallel, but the number of lamellae stacked in the flowing direction did not increase with increasing crystallization time. On the other hand, in situ TEM of an unoriented i-PS thin film showed that a small sheaf-like structure, which consists of several edge-on lamellae, appeared and then these edge-on lamellae grew to make a binocularly developed two-dimensional spherulite. These results indicate that "central entities" (which have been named by us in this study) in the stacked lamellae form at a first stage of isothermal crystallization, and the length and orientation of the "central entities" have an effect on the resulting crystalline morphology after isothermal crystallization. In addition, by real-time in situ TEM of an unoriented i-PS thin film, the growth of i-PS edge-on lamellae were continuously observed for the first time though the image quality at the present stage was not sufficient to clearly identify individual lamellae.

View full abstract

Morphlogy of melt-kneaded blends of amorphous nylon (AmPA) and poly(styrene-co-acrylonitrile) (SAN) was investigated by scanning electron microscopy. Co-continuous morphology was observed for the SAN/AmPA blends in which volume fraction of SAN was nearly equal to that of AmPA. It was found that the continuous structures tend to be enlarged or changed to matrix-droplet morphology with increasing shear rate. In addition, sizes of droplets in SAN/AmPA blends taking matrix-droplet morphology were independent of shear rate and strongly depend on blend composition.

View full abstract

Desized and scoured ramie fabric was treated with liquid ammonia (NH₃) using a practical range. Crystllinity, moisture regain, water absorption, and dyeing properties were measured to investigate the internal structure of the fiber by the NH₃ trestment. Crystallite structure of ramie cellulose I was transformed to cellulose III by the NH3 treatment. Crystallinity was decreased not only by the NaOH but also by the NH₃ treatments, especially by the latter. Water absorption was increased by the NaOH treatment, whereas it decreased by the NH₃ treatment. Early dyeing rate of the fabric was increased considerably with NaOH treatment, while it decreased greatly with the NH₃ and NaOH/NH₃ treatments. Nevertheless equilibrium dye uptake was increased a little by the NH3 treatment. As a measure of fabric hand, shearing and bending hysteresis curves were obtained using KES instrument. Shearing modulus G, bending hysteresis width 2HG, bending modulus B and bending hysteresis width 2HB were obviously decreased by the NH₃ and NaOH/NH₃ treatments.

View full abstract

Antimicrobial activiy against 2 species bacteria of six basic dyes and Benzalkonium chloride as a retarding agent in the dyed acrylic fibers was investigated by mean of JIS test method (JIS L1902). To examine the effect of the dye concentration in the dyed fibers on antibacterial activity, it was represented by SOR that is the ratio of dye concentration in the dyed fibers to its relattive saturation value. Result of JIS test method demonstrated that antibacterial activity of the dyed fibers was obviously revealed and related to minimum bactericidal concentration (MBC) of the respective dyes and Benzalkonium chloride depending on the chemical structure of them. Antibacterial activities in the dyed fibers with the basic dyes of triphenyl-methane, azine, azo and thiazine were compared, which decreased in that order. And antibacterial activity was apt to increase with SOR. Bactericidal activity against Staphylococcus aureus IFO12732 was shown in all dyes except thiazine, whereas that against Escherichia coli K12 W3110 was low activity. Benzalkonium chloride was equally effective against both bacteria and improved antibacterial activity in the dyed fibers with lower SOR level of Malachite Green.

View full abstract