Noise in weaving mills becomes much louder with increasing speed of weaving machine. One of the sources of the noise is the collision of healds caused by shedding motion on a loom. It was clarified in the previous report that the sound caused by shedding motion was significantly connected with heald motion during a period of shedding motion. In this report, vibration and noise characteristics when changing warp density are investigated using a short time fourier transform and high-speed camera in order to relate the sound to the heald motion in a period of shedding motion. As a result, it is found that the noise between upper and lower dead of shedding motion at low warp density is larger than the noise at high warp density. This is because the lateral movement of the heald after jumping become free due to low warp density and the collision energy of each heald is increased.
The current focus on renewable energy is driving installation of a growing number of wind turbines. In recent years, efforts to improve power generation efficiency by using larger turbine blades have resulted in higher blade tip speeds. The glass fiber reinforced plastic (GFRP) used for blade surfaces is subject to wear due to particle impingement from wind, rain, and dust during long-term operation. As the mechanical effect of such particle impacts, erosion is a factor in blade failure. In addition, long-term exposure of operating turbines to sunlight leads to ultraviolet (UV) degradation, which makes blade failure more likely by accelerating erosion. Addressing this issue requires erosion-resistance measures that take into account the effects of UV light, but the precise nature of the relationship between UV degradation and erosion mechanisms remains unclear. In this study, we investigate those mechanisms by reproducing particle impingement on GFRP exposed to UV light in an effort to lay the foundation for more effective erosion-resistance measures. As a result, we clarify that a decrease in the interfacial strength between the fiber and resin is the dominant factor in the process by which UV degradation accelerates erosion in wind turbine blades.
Slide fasteners are one of the textile end-uses that have permeated daily life. The objective is to elucidate ways to improve the quality and value of slide fasteners. In this report, from the viewpoint of tactile perception on the tensile load transmitted to user’s fingers through a slider in sliding a fastener, the sensory and affective impressions (hereinafter referred to as the slide-feeling) and the quantitative evaluation indexes on the slide-feeling were investigated. In the evaluation of the slide-feeling on the tactile perception of the slide fastener, the term related to Light/Smooth, i.e., one of “Smooth,” “Not stiff,” “Light,” “Flat,” “Loose,” “Readily,” and “Supple,” and the term of “Luxurious” are main evaluation terms. For the term related to Light/Smooth, the energy of tensile load from the stationary state to the moving start of the slider and the average value of tensile load from the begin to the end of the slider move are effective evaluation indexes. The term of “Luxurious” requires evaluation indexes other than the followings; the energy of tensile load from the stationary state to the moving start of the slider and the average of tensile load from the moving start to the moving end of the slider.
To prepare structural colored fibers by a cholesteric liquid crystal (CLC), cellulose derivatives forming a CLC structure under a room condition were synthesized through the esterification of hydroxypropyl cellulose (HPC) with propionic an hydride. Obtained cellulose derivatives formed CLC under room conditions within the degree of esterification by propionic acid (PA) from 0.83 to 1.1 per glucose unit. It was also possible to mold a film shape or a fiber shape. The derivative was possible to exhibit structural color under a room condition when it contained moisture more than 13.76 wt% after the preparation and 1.85 wt% at the time of exhibiting color. The glass transition temperature of the HPC derivative was between 5-13 °C. Its CLC structure was reconstructed under a room condition after destroyed the CLC structure by straining. The structural colored fiber was wet spun with the HPC derivative acetone solution to water as a coagulation bath. The specular reflection spectrum of the fiber showed the angle-dependence according to Bragg’s law. The pitch of CLC structure in the fiber was 423 nm, and the size of the CLC domain was 5.13 μm. In the scattering spectrum of the fiber, a reflection peak was observed in the fiber diameter direction regardless of the scattering angle, which suggests that the CLC domains have anisotropy and is radially oriented in the radial direction from the center of the fiber.
Organic/inorganic composite aerogels were obtained from poly-paraphenylene terephthalamide (PPTA) micro-fibrils and methyltrimethoxysilane (MTMS). They are prepared using the following four-step process: the gelation of 1.0 wt% PPTA fibril dispersion containing MTMS by cooling, dehydration condensation of MTMS by immersing the wet gel in a catalyst solution, substituting the solvent in the wet gel, and supercritical drying of the wet gel. When the PPTA/MTMS dispersion containing 1.0 wt% MTMS was gelatinized, the PPTA fibrils strongly adhered to each other, and the PPTA/MTMS composite wet gel obtained better morphological stability. Furthermore, the wet gel prevented shrinkage during the catalyst soaking and supercritical fluid drying processes, and the resulting aerogel had a minimum density of < 0.03 g/cm3. It also had a composite network structure with silica spheres of approximately 30 nm attached to the PPTA fibril network. In contrast, when the PPTA/MTMS dispersions containing 5.0 or 10 wt% MTMS were gelatinized, the obtained composite aerogels had an entangled structure of PPTA fibril networks around silica spheres ranging from 500 nm to 700 nm in size. Moreover, aerogels comprising PPTA/MTMS dispersion with 10 wt% MTMS had a specific surface area of 610 m2/g and retained 70 % of their weight after the heat resistance evaluation at 600°C.