Melt blowing is a one step process which produces nonwoven fabrics by extending the extruded polymer melt with a jet of hot air that rapidly attenuates the extrudate into small diameter fibers. Unstable behavior of melt-blowing process was investigated through experimental analysis and numerical analysis. Polypropylene (PP) with different melt flow rate (MFR) were used in experimental analysis. Stability of the process was evaluated by measurement of fiber diameter distribution in the resultant web. In addition,thinning behavior of spin-line near the spinneret was observed by using a high-speed camera. Broadening of fiber diameter distribution was observed in the spinning conditions of small throughput rate or high airflow rate. Periodic fluctuation of fiber diameter was also observed in those spinning conditions. It indicated that the diameter distribution was caused by instability of spin-line. For the PP of low viscosity, instability of the process dominated by throughput rate. On the other hand, airflow rate was more effective on instability of high viscosity PP. These results suggested that the two different origins were existed. To investigate the mechanism of instability in melt-blowing process, numerical analysis was conducted using newly developed simulation system based on Lagrangian coordinate system. Results of numerical analysis suggested that the origin of instability of small throughput rate with low viscosity PP was surface tension of molten polymer. In addition, the other origin of instability noticeable in high airflow rate was resonance between spin-line and turbulence of blowing air.

We used our new nozzle-free melt-electrospinning (M-ESP) system to produce polypropylene (PP) nanofibers. The M-ESP system includes a line-like CO₂ laser beam melting device. We fabricated core (PP)-clad [poly(ethylene-co-vinyl alcohol; EVOH] nanofibers from EVOH (melt flow rate [MFR]: 14 g/10 min)/PP (MFR: 12 g/10 min)/EVOH three-layer sheets using the M-ESP system. The core-clad structure was formed by a wrapping phenomenon that is the result of the difference in the MFR values of the EVOH and PP melts. By removing the EVOH, we obtained PP nanofibers with the avg. dia. of 0.21 µm from the core-clad nanofibers. The nanofiber dia. was decreased by decreasing the MFR of the PP melt and the thickness of the PP layer in the EVOH/PP/EVOH sheet.

In this study, we have examined a mechanism to fabricate cellulose nanofiber actuators using conducting fabrics. The conducting fabrics were successfully attached to both the layers of 2,2,6,6-tetramethylpiperidinyl-1-oxyl radical (TEMPO)-oxidized cellulose nanofiber (TCNF) films using a simple heat-press method,and the obtained actuators functioned as bending-type actuators. TCNF exhibits a polyelectrolyte structure and can induce iontophoresis under an applied electric field. The observed bending motion of the TCNF actuators can be attributed to iontophoresis when an electric potential was applied. The fabrication method reported herein does not require the usual electroless plating processes but requires only the simple heatpress processes to adhere the conducting fabrics onto the TCNF film. It is expected that this simple approach will result in new possibilities and promote the development of polymer actuators based on cellulose nanofibers.

Polypropylene (PP) fibers have various excellent characteristics. However, it is difficult to use PP fibers for fashionable apparels due to its poor dyeing properties. Hence, in this paper, it has studied that developing a novel simple and inexpensive dyeing method for PP fibers by utilizing a cationic dye. It was developed that the PP dyeing method with the reduced form of a cationic dye, namely, leuco form. In the method, the permeability and affinity of the cationic dye for PP fibers would have been enhanced by reducing the cationic dye treated with a reducing agent in the alkaline aqueous solution. As a result, the reduced form of the cationic dye was adsorbed onto the PP fibers. Although, the color of the dye disappeared under an alkaline condition, the adsorbed cationic dye was recolored and fixed by treating with an oxidizing agent, and the dyed PP fibers were obtained. Following aforesaid method, the dyed PP fabrics were obtained by reducing the cationic dye with glucose under an alkaline condition at 100 ̊C and oxidizing it in an aqueous acetic acid solution at 50 ̊C. It was found that the L* of the dyed fabrics were low when Basic Blue 3, Basic Red 2, Basic Yellow 7, and Basic Orange 14 were used as a cationic dye.