The study of the mechanical deformation behavior is indispensable for endowing more excellent mechanical property to the fibers. In particular the information on the behavior of the crystalline region is basically important. One typical experiment is to trace the structural change in the crystalline (and amorphous) region of the fiber subjected to a tensile force by measuring the change of the X-ray scattering pattern, for example. In principle, the mechanical property of the crystalline phase should be constant as an ultimate property of the semi-crystalline polymer materials. However, the actually detected mechanical deformation behavior of the crystalline region is not constant always but it changes sensitively depending on the sample preparation condition or the higher-order structure. This apparently curious behavior comes from the heterogeneous stress distribution in the fiber, which is speculated to be caused by the existence of the highly-tensioned tie chains in the amorphous region passing through the stacked lamellae. In the present article the important roles of the taut tie chains are reviewed concretely from the various aspects including the quantitative evaluation of the Youngʼs modulus along the chain axis (crystallite modulus), the clarification of the stress-induced phase transition, the improvement of the stress cracking property, the interpretation of fracture phenomenon and so on.

Fabrics woven with paper yarns show the higher cool touch feeling rather than conventional cotton yarn fabrics. We evaluated semi-quantitatively the transverse heat conduction of a single paper yarn to elucidate its high cool touch feeling and discussed the origin of the high heat conduction on the context of the inner structure of the yarn comparing with the cotton yarn. Thermo-sensitive inks show chromatic changes depending on temperature and we applied the ink on the single yarn as a thermo-indicator. The time depending temperature of the single paper yarn after contact on a heated metal plate showed a faster increase than that of the cotton yarns indicating the higher transverse heat conduction of the paper yarn. The observations of the microstructure of the yarns were investigated by Scanning electron microscope (SEM). It was inferred that the less anisotropy of the fiber orientation and the tight packing of the fibers in the paper yarn should be the structural origin of the higher transverse heat conduction of the paper yarn giving rise to the higher cool touch feeling.

Hierarchically unique morphologies were observed inside microspheres with a diameter of 70-80 µm fabricated with the combination of a microfluidic emulsification and a solvent-evaporation method, which were based on binary polymer blends consisting of poly(styrene) (PS) / poly(methyl methacrylate) (PMMA) and poly [4-(N, N-diphenylamino)styrene] (PDAS) / PMMA. The phase separated structure in composites was dependent on type of hydrophobic polymer, the molecular weight of polymers, and the evaporation rate. The particles prepared from high-molecular weight components exhibited macroscopically phase separated structure (incomplete core-shell). In addition, PS / PMMA composite showed the hierarchical microscopic phase separated structure, spherical PMMA domains dispersed in the PS-rich core in the macroscopic core-shell structure. Low molecular PS / PMMA composite formed macroscopically homogeneous, but microscopically bi-continuous phase separated structure. Low molecular PDAS / PMMA composite also afforded the hierarchical structure, where the macroscopical core-shell structure (pseudo core-shell) existed, and the shell contained dispersed micron-sized PDAS domain in PMMA phase, and the core exhibited the bi-continuous structure comprised both components. This hierarchical structure is considered to be formed due to the kinetical limitation, and this was more simplified and thermodynamically more stable structure (sea-island) by lowering the evaporation rate. It is noteworthy that the uniform sized microspheres with hierarchical structure were fabricated only from homopolymer blends without the assist of block or graft copolymer.