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Some Results of Recent Investigation and Application of Rubber Blends in Vietnam
Bui Chuong,Nguyen Thanh Liem,Dang Viet Hung,Nguyen Huy Tung,Nguyen Pham Duy Linh,Nguyen Thanh Nhan,Pham Ngoc Linh,Le Anh Kien,Chu Chien Huu 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
We have investigated the change of tensile strength (TS) of Natural rubber/chloroprene rubber (NR/CR) blends during combination ageing, including heating and dynamic mechanical loading. Using model of statistical experiment, we built the equation describing the dependence of TS on four factors: temperature T, number of cyclic loadings N, contents of NR (C<sub>NR</sub>) and chloroprene (CCR). This equation allows predict the TS change of NR/CR blends after combination ageing with accepted inaccuracy – less than 10%. We also investigated the effect of nanofillers, such as nanoclay, SiO2, Fe<sub>3</sub>O4, on adhesion of some rubber blends to polyester and steel cords. It was found, in the case of EPDM/CIIR rubber blends, both nanoclay and SiO2 have no effect on adhesion to steel cords, while nano SiO2 may enhance adhesion to polyester cords. On other side, Fe<sub>3</sub>O4 may remarkably enhance adhesion of NR/CR blends to steel. Mentioned results are successfully applied in some practical rubber products working under fatigue conditions, such as rubber/steel antivibration pad for locomotive, heat resistant conveyor, water dam, underwater lift bag.
Minh Hieu Nguyen,Thanh Tung Ha,Sy Sua Tu,Thanh Chuong Nguyen 서울시립대학교 도시과학연구원 2019 도시과학국제저널 Vol.23 No.4
Creation of an effective bus rapid transit (BRT) system has never been an easy task, especially for the first case in a developing country, since a BRT project requires a considerable investment with participation from most walks of life. Hanoi, the capital of Vietnam, has omitted to overcome impediments in the maiden BRT establishment. The Hanoi BRT performs poorly with ridership at only 13,500 passengers per day. In this paper, it is scrutinized based on a series of barriers that are findings in previous works and in the shape of a theoretical framework with seven main categories, namely: (1) institutional and legislative context, (2) political leadership and commitment, (3) physical design and operation, (4) management of competing modes, (5) adequate funding, (6) public participation and (7) image promotion. Results emphasize that the difference in views of the funder and the local authorities on the BRT development is the chief barrier. Enforcement of the BRT lanes from motorcycles is demanding, which is distinct from cities previously creating BRT. The findings from the Hanoi BRT are not unique. Lessons drawn from its failure could be widely informative for the BRT establishment in a number of cities with similar contexts.
Nguyen, Dinh Chuong,Tran, Duy Thanh,Luyen Doan, Thi Luu,Kim, Nam Hoon,Lee, Joong Hee American Chemical Society 2019 Chemistry of materials Vol.31 No.8
<P>Developing efficient and cost-effective bifunctional electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly important for fabricating energy conversion and storage technologies, such as fuel cells, water electrolyzers, and metal-air batteries. Herein, we report a facile and economical route for synthesizing ultrasmall molybdenum phosphide (MoP<SUB><I>y</I></SUB>) nanocrystal-attached mesoporous manganese phosphides on N,P-codoped graphene nanosheets, which display equivalent ORR (OER) activity to that of Pt/C (RuO<SUB>2</SUB>) catalysts. This is manifested by the positive onset potential (0.969 V) and half-wave potential (0.842 V) for ORR, as well as a mere overpotential of 301 mV at a current density of 20 mA·cm<SUP>-2</SUP> and a small Tafel slope of 105 mV·dec<SUP>-1</SUP> for OER in alkaline medium. It also demonstrates remarkable stability in comparison with Pt/C and RuO<SUB>2</SUB> for both ORR and OER, respectively. The excellent performance can be attributed to the mesoporous structure with enhanced multiple types of electroactive sites, which highly favors the adsorption and catalyzation of reactants, as well as efficient reagent/product mass transport. The findings can pave a new way for the synthesis and usage of a hybrid as a bifunctional catalyst with high efficiency and outstanding longevity to enable next generation of energy conversion and storage.</P> [FIG OMISSION]</BR>
Chuong, Nguyen Dinh,Thanh, Tran Duy,Kim, Nam Hoon,Lee, Joong Hee American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.29
<P>In this study, a facile approach has been successfully applied to synthesize a hierarchical three-dimensional architecture of ultrasmall hematite nanoparticles homogeneously encapsulated in MoS<SUB>2</SUB>/nitrogen-doped graphene nanosheets, as a novel non-Pt cathodic catalyst for oxygen reduction reaction in fuel cell applications. The intrinsic topological characteristics along with unique physicochemical properties allowed this catalyst to facilitate oxygen adsorption and sped up the reduction kinetics through fast heterogeneous decomposition of oxygen to final products. As a result, the catalyst exhibited outstanding catalytic performance with a high electron-transfer number of 3.91-3.96, which was comparable to that of the Pt/C product. Furthermore, its working stability with a retention of 96.1% after 30 000 s and excellent alcohol tolerance were found to be significantly better than those for the Pt/C product. This hybrid can be considered as a highly potential non-Pt catalyst for practical oxygen reduction reaction application in requirement of low cost, facile production, high catalytic behavior, and excellent stability.</P> [FIG OMISSION]</BR>
Thanh, Tran Duy,Chuong, Nguyen Dinh,Hien, Hoa Van,Kim, Nam Hoon,Lee, Joong Hee American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.5
<P>Development of a robust, cost-effective, and efficient catalyst is extremely necessary for oxygen reduction reaction (ORR) in fuel cell applications. Herein, we reported a well-defined nanostructured catalyst of highly dispersed CuAg@Ag coreshell nanoparticle (NP)-encapsulated nitrogen-doped graphene nanosheets (CuAg@Ag/N-GNS) exhibiting a superior catalytic activity toward ORR in alkaline medium. The synergistic effects produced from the unique properties of CuAg@Ag core-shell NPs and N-GNS made such a novel nanohybrid display a catalytic behavior comparable to that of the commercial Pt/C product. In particular, it demonstrated a much better stability and methanol tolerance than Pt/C under the same conditions. Because of its outstanding electrochemical performance and ease of synthesis, CuAg@Ag/N-GNS material was expected to be a promising low-cost catalyst for ORR in alkaline fuel cell applications.</P>
Relaxor characteristics of PSLZT-BMT-based ferroelectric material ceramics
Nguyen Van Thinh,Le Dai Vuong,Do Viet On,Truong Van Chuong,Le Vu Truong Son,Trinh Ngoc Dat,Le Van Thanh Son,Vo Thanh Tung 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3
(1-x)[(Pb0.94Sr0.05La0.01)(Zr0.54Ti0.46)0.9975O3]-x[Bi(Mn1/2Ti1/2)O3] (PSLZT-BMT) ferroelectric material ceramics with x in therange of 0-0.05 mol were successfully synthesized following the conventional solid-phase route. The materials were thoroughlyinvestigated to study their structural phase, microstructure, ferro-piezoelectric characteristics, and dielectric behavior. Theexperimental results show that the density of the samples decreased from 7.75 to 7.58 g/cm3, and the relative density decreasedin the range of 98.48%-96.28%. However, with increasing contents of BMT, the dielectric and ferroelectric properties ofPSLZT-BMT ceramics tend to decrease, specifically the maximum dielectric constant (εmax) of PSLZT-BMT decreased in therange of 23579-9991 and the residual polarization (Pr) decreases in the range of 22.54-7.87 μC/cm2 when the doping contentincreased in the range of 0.0-0.05 mol. The diffusivity values (γ) of the PSLZT-BMT material are 1.74, 1.78, 1.82, 1.84, 1.79,and 1.77 when the doping content x varies as 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05 mol, respectively, which is characteristic ofrelaxor ferroelectric materials. Besides, the Tm, TB, TC-W, and C values depend on BMT concentration, and the trend decreases.
Thanh, Tran Duy,Chuong, Nguyen Dinh,Hien, Hoa Van,Kshetri, Tolendra,Tuan, Le Huu,Kim, Nam Hoon,Lee, Joong Hee Elsevier 2018 Progress in materials science Vol.96 No.-
<P><B>Abstract</B></P> <P>Recently, the research effort on two-dimensional transition metal dichalcogenides/graphene (2D-TMDs/Gr) hybrids has grown. These hybrids are emerging as a promising strategy for the preparation of advanced multifunctional materials with effectively upgraded properties, as well as performances. Due to their outstanding electrical, physical, and chemical properties, these materials have been extensively considered for various applications, both in academia, and industry. This review systematically assesses the important progress to date in the development of 2D-TMDs/Gr hybrids. The synthesis methods of 2D-TMDs/Gr hybrids for fabricating diverse types of nanostructured architectures are highlighted. In addition, the relationships between morphological and structural characteristics, and the physicochemical properties of 2D-TMDs/Gr hybrids, are recognized in detail. This review also discusses recent prospective applications of the 2D-TMDs/Gr hybrids in the areas of energy storage, energy conversion, energy harvesting technologies, and sensors. In summary, although there are still challenges for optimizing the synthesis process and performance of the 2D-TMDs/Gr hybrids, they offer unique candidates for a wide range of promising applications in the future.</P>
PHAM, Hong Chuong,NGO, Duc Anh,LE, Ha Thanh,NGUYEN, Thiet Thanh Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8
This study exemines the roles of corporate social activity (CSR) and executive compensation structure on the pricing of seasoned equity offerings (SEOs) with special focus on the role of CSR in reducing the level of information asymmetry between managers and future shareholders of issuing firms through SEOs. This study also investigates the interaction between executive compensation structure and CSR on the discounting of SEOs. We use a sample of 2,102 seasoned equity offerings of U.S. firms with CSR scores from 1995 to 2015 in our OLS fixed effect regression analysis. The results show that issuing firms with high CSR are more likely to expericence a lower degree of the SEO discount. The results also document a positive association between CSR and a high proportion of equity-based compensation of issuing firms' executives. The findings of this paper confirm that CSR attenuates the impact of information asymmetry and the pre-SEO price uncertainty on the pricing of the offers and hence the SEO discount. Furthermore, CSR reinforces the impact of executive firm-related wealth on the discounting of seasoned equity offerings. It appears that firm-related wealth motivates managers to actively engage in reducing information asymmetry activities before SEOs, thereby decreasing the SEO discount.
Hien, Hoa Van,Thanh, Tran Duy,Chuong, Nguyen Dinh,Hui, David,Kim, Nam Hoon,Lee, Joong Hee Elsevier 2018 Composites. Part B, Engineering Vol.143 No.-
<P><B>Abstract</B></P> <P>In this study, a novel hierarchical porous network of Pt<SUB>51</SUB>Pd<SUB>49</SUB> alloy-integrated graphene nanosheet as active catalyst towards ethanol oxidation was fabricated using electroless deposition followed by chemical vapour deposition for the first time. Such materials were obtained as a three-dimensional continuous and non-order porous architecture with good dispersion and uniformity of the ultrasmall Pt<SUB>51</SUB>Pd<SUB>49</SUB> nanoalloy particles (∼3 nm) within the graphene nanosheets. As an electrocatalyst, it exhibited excellent catalytic behaviour towards ethanol oxidation with superior conversion, long-term stability and better tolerance towards intermediate's poisoning effect, as compared to commercial Pt black product. The results were associated with the enhanced electroactive surface area and mass transfer possibility of the catalyst due to the formation of an unique porous nanostructure for Pt<SUB>51</SUB>Pd<SUB>49</SUB> alloys. In addition, the coating effect of graphene nanosheets over Pt<SUB>51</SUB>Pd<SUB>49</SUB> alloy nanoparticles avoided aggregation and dissolution, possibly allowing full utilization of the active sites from all nanoparticles, and thus efficiently improving charge transfer ability and working stability of the catalyst. Owning high quality, good electrochemical performance, and ease of synthesis, the as-synthesized catalyst opens an interesting nanoarchitecture class for efficiently catalyzing ethanol oxidation in fuel cells.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>