In this study, the foaming of nonwoven fabrics and bulk polymers was investigated. Four different polymers that are commonly used for textiles including polyethylene terephthalate, thermoplastic polyurethane, thermoplastic polyether ester elastomer and polypropylene were foamed by batch foaming. Among the polymers, thermoplastic polyurethane seems to be the most promising material since it possesses the highest cell density and smallest cell size. In addition, nanoclay was added to thermoplastic polyurethane to promote cell nucleation and to increase the cell density. The results showed that well dispersed nanoclay in thermoplastic polyurethane served as an excellent nucleation agent and the cell structure was improved. The cell size of thermoplastic polyurethane nanocomposite foam decreased to 1 µm while the cell density increased to 3 × 1011 cells/cm3.
Large-scale
ultrathin γ-MnO2 nanosheets form a
continuous wall-like enclosed network directly grown onto the surface
of carbon cloth (CC) fibers. In a simple green electrochemical deposition
process, the CCs were pretreated under acid condition and subsequently
attached by carbon nanotubes with silver nanoparticles (AgCNTs), forming
a three-dimensional (3D) hierarchical heterostructure of MnO2-decorated AgCNT CC fibers (MnO2-AgCNT-CC). The structure,
phase purity, and morphology of the samples were characterized by
field emission scanning electron microscopy (FESEM), high-resolution
transmission electron microscopy (HRTEM), X-ray diffraction (XRD),
Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical
techniques. The MnO2-AgCNT-CC composite had high specific
capacitance (up to 325 F/g at 1 A/g) and long cycle-life stability.
These outstanding electrochemical characteristics were attributed
to the unique 3D porous MnO2 nanowalls and AgCNT composites,
increasing ion-accessible surface area and shortening cation/electron
transportation pathways, thus endowing the electrode with carbon fibers
with good capability and long-term cycling stability, lucrative for
large-scale energy storage applications. The simplicity of the developed
fabrication process is appealing to the large-scale production of
MnO2-based materials on commercial CC fibers and for adaptation
to roll-to-roll manufacturing through a continuous-fabrication process,
widening its applicability.
In this study, the mechanical properties of submicrocellular or nanocellular thermoplastic polyurethane (TPU) nanocomposite foams were investigated via batch foaming using CO 2 as the blowing agent. Cloisite 30B nanoclay (clay 30B) was the nucleation agent. Adding clay 30B and foaming at 60 °C resulted in a nanocellular foam. A cell size of 450 nm and a cell density of 10 11 cells/cm 3 were obtained. The relative density of the foam was within the range 0.9−0.95. The modulus of the foamed samples was found to be proportional to their relative density regardless of their structure (microcellular/submicrocellular). The results indicated that the modulus of the foamed samples with a cell size larger than 400 nm decreased with foam density. However, to our surprise, although adding only 1 wt % of nanoclay reduced the foam density, an increase in the modulus was observed. In addition, the cells became small and uniform.
Risk management has been an essential issue in the evolution of air-force flight safety. In this paper, the investigated risk management of air-force flight training in the Gangshan airbase, Republic of China (ROC) is the main field of study. The main goal of this paper is to conduct a series of risk identification and assessments of the flight training. Firstly, the 16 risk factors (RFs) of flight training were identified according to the related studies of flight safety and risk and three experts’ interviews. Then, we created a fuzzy-analytic hierarchy process questionnaire and interviewed 20 flight instructors to obtain the weight of likelihood and consequence of the 16 RFs. Furthermore, a sequential assessment of the risk matrix was constructed to classify the 16 RFs into four groups, namely, extreme risk, high risk, medium risk, and low risk. As the results of the revised risk matrix, we provided four suggestions for the improvement of flight-training policy. These suggestions not only can facilitate the Gangshan airbase to smoothly transfer and reduce the deadly risk of flight training, but also provide exemplary risk management for other similar airbases.
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