Materials Sciences and Applications

Journal Information
ISSN / EISSN : 2153117X / 21531188
Current Publisher: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 1,090
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Tomoji Ohishi, Kenta Ueguri, Keigo Nakamura
Materials Sciences and Applications, Volume 12, pp 135-149; doi:10.4236/msa.2020.122008

Abstract:
Hydrogen has been recently attracted much attention with respect to high energy-conversion efficiency and low environmental burden. However, hydrogen gas is dangerous due to an explosive gas and a fast combustion rate. Therefore, the development of hydrogen sensor with high accuracy and reliability that can detect hydrogen easily is required. Especially, a flexible hydrogen sensor is useful because it has a high degree of freedom with respect to the shape of location in which the sensor is to be located. A flexible hydrogen sensor—namely, a WO3 thin film formed on a PET film by the sol-gel method using photo irradiation—based on gasochromism of WO3 was developed. By irradiating a thin film, which was prepared by using WO3 precursor solution synthesized by the sol-gel method, with ultraviolet rays, a high-purity WO3 film could be prepared on PET at low temperature. The sensor was structured as a polystyrene (PS) film containing palladium (Pd) laminated on a WO3 film. The WO3 layer was porous, so the PS containing Pd atoms solution penetrated the WO3 layer. WO3 reacted with hydrogen gas and instantly turned blue as the transmittance of the WO3 layer changed. The sensor showed high reactivity even for hydrogen concentration below 4% (1%, 0.5%, 0.25%, and 0.1%), which was the lower limit of hydrogen ignition, and a linear relationship between hydrogen concentration and change in transmittance was found. Moreover, the resistance of the WO3 film significantly and instantaneously changed due to hydrogen-gas exposure, and the hydrogen concentration and resistance change showed a linear relationship. It is therefore possible to quantitatively detect low concentrations of hydrogen by using changes in transmittance and resistance as indices. Since these changes occur selectively under hydrogen at room temperature and normal pressure, they form the basis of a highly sensitive hydrogen sensor. Since the developed sensor is flexible, it has a high degree of freedom with respect to the shape of location in which the sensor is to be installed
Aruoture Egoh, Kischa S. Reed, Peter N. Kalu
Materials Sciences and Applications, Volume 11, pp 415-430; doi:10.4236/msa.2020.117028

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Eric Sakué Ngankam, Lemankreo Dai-Yang, Baissassou Debina, Abdellaziz Baçaoui, Abdelrani Yaacoubi, Abdoul Ntieche Rahman
Materials Sciences and Applications, Volume 11, pp 382-400; doi:10.4236/msa.2020.116026

Blaise Awola Ayirizia, Yuriy Malozovsky, Lashounda Franklin, Uttam Bhandari, Diola Bagayoko
Materials Sciences and Applications, Volume 11, pp 401-414; doi:10.4236/msa.2020.117027

Mika Vähä-Nissi, Panu Lahtinen, Emmi Nuutinen, Timo Kaljunen, Tiina Pöhler
Materials Sciences and Applications, Volume 11, pp 27-43; doi:10.4236/msa.2020.111003

Abstract:
The purpose was to test the feasibility of preparing cast films directly from an aqueous suspension of alkaline pretreated and fine milled chicken feathers, and to evaluate the impact of different additives on film formation and the tensile properties of the resulting films. The feather suspension consisted of stiff and sharp-pointed fibers together with more round-shaped fines. Films cast from this suspension were opaque and porous. While films without additives were fragile with drying-induced defects, film formation was improved with additives, especially with ethanolamine and maleic acid at 20% and 30% concentrations. A synergistic plasticizing effect was observed with ethanolamine and formamide, and strength of the films was improved with sodium alginate. However, the overall impact of additives on the tensile properties in general and strain at break in specific was limited. This was likely due to the dominating role of the porous film structure and the stiff fibers with a limited reactivity towards the additives.
Tomoji Ohishi, Kousei Ichikawa, Satoki Isono
Materials Sciences and Applications, Volume 11, pp 58-69; doi:10.4236/msa.2020.111005

Abstract:
Flexible electronics have been recently paid much attention. A flexible substrate (Organic resin film) is indispensable component for flexible devices. Though PET film is low-cost organic film, low heat-resistance of PET film limits its application as a flexible device substrate. We have developed heat-resistant PET which does not deteriorate even at 190°C heat treatment for one hour. An excimer light was irradiated onto a polysi-lazane (PHPS: perhydropolysilane)-coated film to form a dense silicon-dioxide (SiO2) layer on a PET film, and the heat-resistance property of the formed film was examined. Changes of surface state and cross-sectional structure of the formed film due to heat treatment were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). Compared to normal PET, which is deteriorated and whitened by heat treatment of about 110°C - 120°C, the SiO2-coated PET film maintains transparency and does not deteriorate after heat treatment at 180°C - 190°C for one hour. This high heat resistance is due to a dense SiO2 film formed on the surface that prevents surface precipitation and crystallization of low-molecular-weight oligomers (which are the cause of thermal degradation of PET). It is expected that enhancing the heat resistance of PET—which has high versatility and low cost—to about 180°C to 190°C will allow SiO2-film-coated PET to be developed as a film substrate for flexible devices.
Takashi Kawabata, Yusuke Takahashi, Yasumitsu Matsuo
Materials Sciences and Applications, Volume 11, pp 1-11; doi:10.4236/msa.2020.111001

Abstract:
In order to investigate a key factor for the appearance of proton conductivity in chitin-chitosan mixed compounds, the chitin-chitosan mixed compounds (chitin)x(chitosan)1-x were prepared and these proton conductivities have been investigated. DC proton conductivity σ is obtained from Nyquist plot of impedance measurement data, and the relationship between σ and mixing ratio x has been made clear. It was found that the x dependence of σ is non-monotonous. That is, σ shows the anomalous behavior, and has peaks around x = 0.4 and 0.75. This result indicates that there exist optimal conditions for the realization of high-proton conductivity in the chitin-chitosan mixed compound in which the number of acetyl groups is different. From the FT-IR measurement, we have found that the behavior of proton conductivity in (chitin)x(chitosan)1-x is determined by the amount of water content changed by x. Using these results, proton conductivity, which is important for the application of conducting polymers in chitin-chitosan mixed compounds, will be able to be easily controlled by adjusting the mixing ratio x.
Harekrushna Sutar, Birupakshya Mishra, Rabiranjan Murmu, Sangram Patra, Sarat Chandra Patra, Subash Chandra Mishra, Debashis Roy
Materials Sciences and Applications, Volume 11, pp 12-26; doi:10.4236/msa.2020.111002

Abstract:
The present experimental work reveals the surface characteristics like wettability, thermal and sliding wear behaviour of plasma-sprayed red mud (RM) coatings premixed with fly ash (FA). Varying weight % of FA (10, 20, 30 and 40)—RM composite powder is used as precursor for coating. Atmospheric plasma-sprayed coatings are developed at different operating power like 5 kW, 10 kW, 15 kW and 20 kW separately on mild steel substrate. Tribological behaviour viz. sliding wear properties are studied at distinct operating load (10N, 15N, 20N, 25N), speed (40 rpm, 50 rpm, 60 rpm, 70 rpm) and track diameter of 100 mm using a pin on disc tribometer for duration of 30 minutes with 3 minute gap period for each experiment. The DSC and TGA experiments of the coatings are performed to understand the high temperature application areas. The contact angle result signifies the wettability of the prepared coatings is principally a function of composition. The reaction of surface roughness and spraying power is in-significant on water contact angle (WCA). In conclusion, the sliding wear experiments are optimized by Taguchi method to ascertain the influencing parameter on wear.
Erika M. Inácio, Diego H. S. Souza, Marcos L. Dias
Materials Sciences and Applications, Volume 11, pp 44-57; doi:10.4236/msa.2020.111004

Abstract:
PLLA-modified cellulose nanocrystals (CNC) were produced from commercial CNC by tin-catalyzed polymerization of lactide in presence of CNC. FTIR spectroscopy demonstrated that the result of the reaction produced the grafting of PLLA chains onto CNC surface (CNC-g-PLLA). Films of poly(lactic acid) (PLA) and PLA/CNC nanocomposites (with non-modified CNC and CNC-g-PLLA) containing 0.5% and 5% (w/w) of the nanofillers were prepared by casting in chloroform solution and the crystallization behavior and thermal properties investigated. All nano-composites had similar thermal stability when analyzed by TGA analyses under an inert nitrogen atmosphere. Addition of both types of CNC influenced crystallization, the higher crystallization rate being observed for 5% (w/w) CNC. Nanocomposites with 5% (w/w) CNC-g-PLLA had the strain resistance of PLA improved in the rubbery state. PLLA-modification of CNC surface increased the crystallization of PLA in PLA/CNC nanocomposites and improved the rigidity at temperatures above the glass transition, properties which are desirable for hot drinking application.
Tomoji Ohishi, Kenta Ueguri, Keigo Nakamura
Materials Sciences and Applications, Volume 11, pp 135-149; doi:10.4236/msa.2020.112008

Abstract:
Hydrogen has been recently attracted much attention with respect to high energy-conversion efficiency and low environmental burden. However, hydrogen gas is dangerous due to an explosive gas and a fast combustion rate. Therefore, the development of hydrogen sensor with high accuracy and reliability that can detect hydrogen easily is required. Especially, a flexible hydrogen sensor is useful because it has a high degree of freedom with respect to the shape of location in which the sensor is to be located. A flexible hydrogen sensor—namely, a WO3 thin film formed on a PET film by the sol-gel method using photo irradiation—based on gasochromism of WO3 was developed. By irradiating a thin film, which was prepared by using WO3 precursor solution synthesized by the sol-gel method, with ultraviolet rays, a high-purity WO3 film could be prepared on PET at low temperature. The sensor was structured as a polystyrene (PS) film containing palladium (Pd) laminated on a WO3 film. The WO3 layer was porous, so the PS containing Pd atoms solution penetrated the WO3 layer. WO3 reacted with hydrogen gas and instantly turned blue as the transmittance of the WO3 layer changed. The sensor showed high reactivity even for hydrogen concentration below 4% (1%, 0.5%, 0.25%, and 0.1%), which was the lower limit of hydrogen ignition, and a linear relationship between hydrogen concentration and change in transmittance was found. Moreover, the resistance of the WO3 film significantly and instantaneously changed due to hydrogen-gas exposure, and the hydrogen concentration and resistance change showed a linear relationship. It is therefore possible to quantitatively detect low concentrations of hydrogen by using changes in transmittance and resistance as indices. Since these changes occur selectively under hydrogen at room temperature and normal pressure, they form the basis of a highly sensitive hydrogen sensor. Since the developed sensor is flexible, it has a high degree of freedom with respect to the shape of location in which the sensor is to be installed
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