bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi-Scale Simulation of Well-Entangled Polymer Melt Flows in a Channel
Authors: Taniguchi Takashi , Sato Takeshi , Harada Kohei 
Published: February 2020

In order to produce better polymeric goods, it is important to predict and to control a flow behavior of a polymeric fluid. To understand a flow behavior of a polymeric fluid, computational approach is quite effective. It is well-known that polymeric fluids exhibit complex flow behaviors owing to a strong correlation between the state of macroscopic flow and the microscopic state of polymer chains. The complex flow behaviors are originated from the stress tensor in the Cauchy momentum equation. When solving the equation, a constitutive equation is usually used to evaluate the stress tensor from the local deformation rate tensor and a set of parameters. By using a constitutive equation, however, it is difficult to reflect the microscopic state to the macroscopic flow. As one of the methods to overcome the difficulty, it has been proposed to use a multi-scale simulation (MSS) method where local microscopic states and the macroscopic flow are directly connecting each other.
So far, the MSS method has succeeded in predicting the flow in simpler geometries such as a flow in between two parallel plates and polymer melt flows passing a circular object in a two-dimensional periodic system. To develop further the MSS method that can deal with more industrially oriented problems, it is necessarily to investigate the applicability of the method to a flow in complicated geometry of boundary. In this context, we have applied the multiscale simulation technique to flows of polymer melts in a channel with 4:1:4 contraction and expansion geometry.
In the MSS method, we introduced Lagrangian particles which contain many chains to precisely maintain the microscopic states. As the microscopic polymer model, a slip-link model is used. Using the multiscale simulation method, we investigated the macroscopic spatial distribution of microscopic quantities, such as the spatial distribution of polymer chain orientation and the number of entanglements. We found that the number of entanglements strongly decreases around the middle of the polymer chains. This kind of information can be helpful when designing polymer melts with specific properties.
Fracture Behavior and Mechanical Properties of Rivet Joint By Using Ultrasonic Vibration with c-Frtp
Authors: Ohtani Akio 
Published: February 2020

Fiber Reinforced Plastics (FRP) have been expected to be used for structural materials in various field because of its high specific stiffness and strength. In the case of using FRP for automotive structures, easy and reliable jointing process in a short time must be needed. Most easy jointing processes are adhesive joint with bonding agent or welding joint in the case of FRTP. However mechanical properties of these joint system depend on the interfacial properties between resin and fiber or resin itself, which are relatively poor. In the case of mechanical joint by using bolt and nut, or rivet system with metal materials, whole structure will be heavy. Therefore if FRP parts could be used as a jointing parts instead of rivets, the problems such as a increase of weight and process time of jointing should be overcome.
In this study, rivet joint with pultruded c-FRTP (continuous Fiber Reinforced Thermoplastic composite) rods with CF/PA commingled yarns covered with braided GF / PA commingled yarns and were performed by using ultrasonic welding machine with a die forming rivets for a pair of c-FRTP (CF/PA) plates with a joint structure. Mechanical properties of rivet joint were investigated by performing single lap joint test, and fracture behavior was also investigated by stopping the test in each region of the obtained diagram and embedding the sample for cross-sectional observation.
Thermal Energy Storage P(BeA-co-MMA) Microcapsules with Excellent Thermal Stability
Authors: Mao Yuchun , Gong Jin , Zhu Meifang , Ito Hiroshi 
Published: February 2020

Latent heat storage systems are a highly efficient and environmentally friendly way to use residual heat and store renewable energy. Phase change materials, which can absorb or release the enthalpy of phase changes in certain temperature ranges, are considered one of the most reliable latent heat storage and thermoregulation materials. Phase change materials have been successfully used in the fields of solar energy, aerospace and aviation, environmental control and textiles. Among phase change materials, paraffin and n-alkane are the most popular due to their characteristics of high phase change enthalpy, high energy storage density, relative low volume change ratio, good physical and chemical stability, and no super-cooling or phase segregation behavior. More importantly, there are wide selective working temperature ranges which greatly extend their operating conditions.
Microcapsules are considered micro scale containers to prevent core from leaking, isolate from the surroundings and maintain chemical and functional stability in service. There are several methods to synthesize microcapsules: spray dying, complex coacervation, sol-gel, in-situ polymerization, suspension polymerization and emulsion polymerization. Among these, suspension polymerization has the advantages of being simple, cheap, stable, eco-friendly and being easily controlled, which makes it the most popular chemical method to synthesize microcapsules. The majority shell materials of traditional microcapsules are synthetic macromolecules. The properties of shell materials impact the application and processing conditions of the final energy storage composite materials greatly. Nevertheless, the low thermal stability and physical strength of polymers in nature strongly restrict application fields of microcapsules. What’s more, the evaporation or sublimation of core materials causes the low thermal stability.
In order to overcome these shortages of shell fracture, core leakage, core evaporation or sublimation existing in traditional microcapsules, we design a copolymer microcapsule with strong interaction force between shell and core parts, which has an unseparated surface layer between shell and core. The strong interaction force between shell and core allows the extreme improvement of thermal stability of microcapsules. The copolymer microcapsule is synthesized by suspension polymerization of behenyl acrylate (BeA) and methyl methacrylate (MMA). In this paper, we report the synthesis, size control and structure analysis of P(BeA-co-MMA) microcapsules which have both excellent thermal stability and high thermal energy storage capacity.
(Keynote) The Versatility of Mesoscopic Solar Cells
Authors: Hagfeldt Anders 
Published: February 2020

In our work on solid-state dye-sensitized solar cells (ssDSSC) we have recently shown that copper phenanthroline complexes can act as an efficient hole transporting material. We prepared ssDSCs with a novel organic dye WS-72 and [Cu(tmby)2]2+/+as redox system and achieved record power conversion efficiencies for ssDSCs of 11.7% [1]. With this redox system DSSCs give also excellent performance under ambient light conditions [2]. Our best DSC efficiency of 13.1% for a liquid Cu-complex electrolyte is achieved by the discovery that the PEDOT based counter electrode can be directly contacted with the dye/TiO2photoelectrode [3]. Thus, there is no space between the two electrodes minimizing diffusion limitations and fill factors up to 0.8 is achieved.
In our work on perovskite solar cells (PSC) we have achieved efficiencies above 20% with a mixed composition of iodide/bromide and methyl ammonium/formamidinium [4]. With the use of SnO2 compact underlayers as electron acceptor contacts we have constructed planar perovskite solar cells with a hysteresis free efficiency above 20% [5,6]. The strategy of cation mixing of the perovskite film was taken further by including the Cs in a so-called ‘triple cation’ composition, i.e. Cs/FA/Ma as well as Rb in a quadruple cation mixture [7,8]. Larger grains grown in a monolithic manner are observed and reproducibility and device stability are improved. For example, above 22% efficiency has been obtained with an outstanding open-circuit voltage of 1.24 V at a band gap of 1.63 eV entailing one of the smallest loss-in-potential of 0.39 V measured for any solar cell material. With regards to lifetime testing, we have shown a promising stability at 85 oC for 500 h under full solar illumination and maximum power point tracking (95% of the initial performance was retained). Recently, we have also commented on the standardization of PSC aging tests [9].

References

[1] Zhang et al. et al., Energy & Envir. Sci.,DOI: 10.1039/c8ee00661j
[2] Freitag et al. Nature Photonics, 11 (2017) 372
[3] Cao et al., Joule, https://doi.org/10.1016/j.joule.2018.03.017
[4] Bi et al., Science Advance, DOI: 10.1126/sciadv.1501170
[5] Correa et al., Energy & Envir. Sci., DOI:10.1039/C5EE02608C
[6] Anaraki et al., ACS Energy Lett. 2018, 3, 773−778
[7] M. Saliba et al., Energy & Envir. Sci., 2016, DOI: 10.1039/C5EE03874J
[8] M. Saliba et al., Science10.1126/science.aah5557 (2016)
[9] Domanski et al. Nature Energy 01 January 2018. DOI: 10.1038/s41560-017-0060-5
(Invited) Micro- and Nano-Structure p-n Junction Based Organophotochatalyst Film
Authors: Nagai Keiji , Ahmad Mohd Fairus , Abe Toshiyuki 
Published: February 2020

The present paper describes organic semiconductor based photocatalyst with p-n junction. A typical material combination is phthalocyanine (H2Pc) and 3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (PTCBI) without transition metal element. It responds full spectrum of visible light and reaching to near infrared region. The film type photocatalyst was prepared by vapor deposition technique with the thickness around 10 to 100 nm, which is relating to absorbance. Typical applicable reactions are downhill redox reaction such as mineralization of volatile organic molecules. The engineering quantum efficiency per incident photon number is high >10 %. When the combination is modified with noble metal nanoparticles or transition metal ion into phthalocyanine, water reduction and oxidation occurred in the presence of bias potential under visible light illumination. Due to the film structure, layering of the film is possible for a practical application, and it is useful to utilise natural sunlight. Under the weak light illumination, internal quantum efficiency becomes high which is merit for the layering use.
By changing microstructure and nanostucture of p-n junction, interesting enhancements were observed, such as near infrared region response maybe due to charge transfer complex formation between H2Pc and PTCBI. A terrace bilayer (TB) of p-n junction exhibited potential structure at the interface and it was observed by the use of scanning Kelvin probe microscopy (SKPM).
1) K. Nagai et al. ChemSusChem,
4 (6), 727-730, (2011).
2) K. Nagai et al. ACS Sustainable Chem. Eng., 1, (8), 1033-1039, (2013).
3) M.-F. Ahmad et al. Electrochemistry
., 86, in press, (2018).
(Invited) Microstructure and Capacity Design of Si-Silicide Alloys As a High-Performance Anode for Li Secondary Batteries
Authors: Umirov Nurzhan , Kim Hyang-Yeon , Kim Sung-Soo 
Published: February 2020

Si and Si-based alloys considered as the most desired anode material for LIB owing to high gravimetric and volumetric capacity (3579 mAh g-1and 2200 mAh cm-3, corresponding to L15Si4 state). Despite academic and industrial efforts, applied on resolving the poor cycle life caused by the large volume changes upon redox reactions with Li+, the commercial use of silicon as an anode has not yet been implemented.
Here, we report a comprehensive study of Si-based binary, ternary and multi alloys prepared by a facile and inexpensive process, melt-spinning. This approach allows to synthesize a proper microstructure by control a certain level of solidification speed (around 103–106 K/s) and known as the most suitable method for the mass production of alloys. In particular, through the control a size of active Si grains, which are well dispersed in the inactive matrix, we have examined electrochemical properties of Si-Ni binary alloys with the different atomic ratio. The gradual change of delithiation curve at 0.3V was observed upon cycling. OCV studies reveal the change of material state and compliment the observation of Chevrier et.al [1]. In our recent studies, we have designed Si–Fe–Al ternary alloys and practically examined the reliability of the proposed capacity prediction approach based on the Lever rule and phase diagram. Accordingly, half-cell electrochemical test results, XRD and TEM investigations revealed fairly good agreement of the calculated and realized capacities of the Si–Fe–Al alloys. Another attempt was applied to design an alloy with nanostructured crystalline Si (active) surrounded by amorphous matrix (inactive). XRD, HR-TEM and DSC results supported the evidence of formation as the designed microstructure. Effect of the amorphous matrix on the electrochemical performance of the Si-alloy as an anode was investigated and will be discussed at the conference.
Reference:
[1] Chevrier, V. L., Liu, L., Le, D. B., Lund, J., Molla, B., Reimer, K., & Eberman, K. W. (2014). Evaluating Si-based materials for Li-ion batteries in commercially relevant negative electrodes. Journal of The Electrochemical Society, 161(5), A783-A791.
Synthesis of Fluorine-Free Polymer Electrolyte Having Lithium Bissulfonimide Unit
Authors: Matsumura Yoshimasa , Shiraiwa Toshiki , Hayasaka Tsuyoshi , Yoshida Saki , Ochiai Bungo 
Published: February 2020

Polymer electrolytes are important materials of Li ion batteries enabling leakage resistance, miniaturization, and thinning. However, the ion conductivities of polymer electrolytes lower than general electrolyte solutions of Li ion battery, limit the performance of cells. To develop novel polymer electrolytes with good ionic conductivity, we focused on the structure of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). LiTFSI is a widely used Li electrolyte salt having high ion conductivity, and its organic structure can be chemically modified. Hence, some polymer electrolytes bearing similar structures were synthesized. However, their ion conductivity are in an insufficient range of 10-5S/cm probably due to their very high Li ion concentrations and high glass-transition temperature (T
g). Herein, we describe the synthesis of a novel polymer electrolytes exhibiting high ion conductivity by copolymerization of lithium N-methanesulfonylvinylsulfoneimide (LiMSVSI) for the electrolyte component with poly(ethylene glycol) methyl ether acrylate (PEGMA) for low T
gand ion conductive pathway (Scheme 1).
The copolymerization of LiMSVSI with PEGMA was carried out by a two-stage heating method. The first stage in ethanol at 60 ºC gave a mixture of the copolymer and the residual monomers. The second stage at 100 ºC after evaporating solvent converted the monomers in quantitatively. The T
gof the copolymer was determined as –62 ºC by differential scanning calorimetry (DSC) analysis. The copolymer exhibited good ionic conductivity in the range of 10-4–10-5 S/cm due to its labile ionic structure and low T
g. In this paper, we will also describe the copolymerization behavior of LiMSVSI with other comonomers.

Figure 1
Catalytic Motifs in Bio-Inspired Materials As New Generation Electrocatalysts
Authors: Coskun Halime , Aljabour Abdalaziz , Stadler Philipp , Sariciftci Niyazi Serdar 
Published: February 2020

Bio-inspired and bioorganic materials gain outmost of interest due to a wide application area. In the past years, hydrogen-bonded organic semiconductors relying on indigoid pigment family are applied in various device geometries e.g. organic solar cells, organic field effect transistors but also as thin film electrodes in catalysis [1,2]. Currently, the integration of the bio-inspired materials in sustainable catalysis is powerful. Especially, organic functionalities present in the chemical structure of this new material class provide these compounds outstanding properties in terms of using these functional themes as catalytic active centers to substitute state-of-the-art metallic catalysts. Herein, we report on the suitability of a bio-originated polymer – Polydopamine (PDA) - as an effective electrocatalyst [3]. Polydopamine is a major pigment of the eumelanin family. Due to its hydrogen-bonded sequences in the conjugated structure, stabilized over hydroxyl, amine and carbonyl groups, PDA is a prominent competitor for the new generation of sustainable catalysis. We engineered a new synthetic pathway for the polydopamine electrode prepraration [4]. We apply the chemical vapor deposition technique in the presence of the monomer dopaminhydrochlorid together with sulfuric acid as an oxidant in order to form polydopamine films directly on 3D, sponge-like carbon felt electrodes, creating an increased catalytically active surface area. Electrochemical investigations exhibit the interaction and interplay of the functionalities in catalytic processes resulting in high yields and current densities and thus reducing energy losses.
[1] Glowacki E. D.; Irimia-Vladu M.; Kaltenbrunner M.; Gasiorowski J.; White M. S.; Monkowius U.; G. Romanazzi G.; Suranna G. P.; Mastrorilli P.; Sekitani T.; Bauer S.; Someya T.; Torsi L.; Sariciftci N. S.; Adv. Mater.,
2013, 25, 1563–1569.
[2] Glowacki E. D.; Romanazzi G.; Yumusak C.; Coskun, H.; Monkowius U.; Voss G.; Burian M.; Lechner R. T.; Demitri N.; Redhammer G. J.; Sünger N.; Suranna G. P.; Sariciftci N. S.; Adv. Funct. Mater.; 2014, DOI: 10.1002/adfm.201402539.
[3] Coskun, H.; Aljabour, A.; De Luna, P.; Farka, D.; Greunz, T.; Stifter, D.; Kus, M.; Zheng, X.; Liu, M.; Hassel, A. W.; Schöfberger, W.; Sargent, E. H.; Sariciftci, N. S.; Stadler, P.; Sci. Adv.
2017, 3 (8), e1700686 DOI: 10.1126/sciadv.1700686.
[4] Coskun, H.; Aljabour, A.; Uiberlacker, L.; Strobel, M.; Hild, S.; Cobet, C.; Farka, D.; Stadler, P.; Sariciftci, N. S.; 2018, 645 (August 2017), 320–325 DOI: 10.1016/j.tsf.2017.10.063.
Study of Sensing Behavior of Conductive Hydrogels
Authors: Ahmed Kumkum , Shiblee MD Nahin Islam , Kabir M. Hasnat , Khosla Ajit , Furukawa Hidemitsu 
Published: February 2020

Hydrogels having shape memory behavior are one of the smart materials with numerous possible application in sensor, optical and biomedical field. Thermo-responsive gels have the ability to show reversible shape transformation due to the melting induced order-disordered transitions of the molecular constituent. Our group has developed poly(dimethyl acrylamide-co-stearyl acrylate (DMAAm-co-SA) based shape memory gels (SMG) [1] with high mechanical strength, very good transparency and biocompatibility having potential application in different sectors [2]. Introduction of conductive properties in hydrogels can create high potential in the field of medical treatment (drug release), electrochemistry (bioactive electrode coating), sensors and actuators. In this work we have focused to combine the tunable physical and mechanical properties of the SMGs with the electrical activity of an electroactive component in order to bring out new prospects in material engineering. However, conductivity is not part of the inherent characteristics of the hydrogels, it can be provided by other materials or particles that are incorporated within the network of the hydrogels (e.g., conductive particles, conjugated polymers, etc.). Fully swollen hydrogels with conducting particles, such as graphite, carbon nanotubes or metallic particles incorporated in their structure typically show conductivity but conductivity is inversely affected by the swelling ratio, and the hydrogels exhibit brittle mechanical behavior [3]. In this work conductivity of the SMGs has been achieved by chemically polymerizing EDOT (with PSS as the molecular dopant) within the network of fully swollen SMG. A wide variety of conductive SMG with tunable mechanical elasticity, softness and swelling degree has been developed by varying crystalline monomer (SA) ratio and comparative study with pristine SMG revealed that conductive network did not affected their swelling degree and mechanical properties extremely. Conductive SMGs with low SA content has been found to be highly conductive with high swelling degree compared to the SMG with high SA content. We studied their electric resistance as a function of applied pressure or strain and developed an Arduino based systems for application in force sensing resistor devices.

References

[1] Kabir, M.H., Ahmed, K. Furukawa, H., Microelectron. Eng. 150, 43–46 (2016).
[2] Amano, Y; Hidema, R; Gong, J; Furukawa, H. Chem Lett.,41, 1029-1031 (2012)
[3] Morita, S; Kawai, T; Yoshino, K. J. Appl. Phys., 69 (8), 4445−4447 (1991).
(Invited) Mechanisms and Material Impacts of Overcharge in Lithium Ion Batteries
Authors: Torres-Castro Loraine , Lamb Joshua , Karulkar Mohan 
Published: February 2020

Traditional monitoring of electrochemical cells and batteries has been limited to observation of voltage and temperature of the cell or cells. While this monitoring can be very robust, there are limits to how predictive voltage and temperature behavior can be prior to a thermal runaway event. Ultimately, voltage and temperature changes are often lagging symptoms of battery failure, and by the time a noticeable change is detected, it is too late to arrest cell failure with intervention or maintenance. Further, instantaneous voltage and temperature monitoring are often inadequate to determine the state of a battery at rest, particularly if the battery has been previously subjected to an abusive condition. Knowledge of the level of stability of a damaged battery would allow for both safer and more efficient handling of the abused battery.
This work examines the application of Electrochemical Impedance Spectroscopy (EIS) and Differential Capacity calculations (dQ/dV) as tools for determining the state of stability (SOS) of an electrochemical cell or battery. The cells used for this study were commercial 10 Ah NMC pouch cells and 10Ah LFP cells subjected to electrical and thermal abuse coupled with EIS monitoring. This aims to not only provide a deeper understanding of how abused cells and batteries fail but also form the technical basis of a tool that could ultimately be used to interrogate cells of unknown stability and even monitor active cells for early signs of damage or failure. Fast impedance monitoring hardware previously developed at Idaho National Laboratory is used to provide not only monitoring after an abusive battery test but also look for changes in the cell while abusive conditions are applied. Differential capacity calculations are explored both before tests and after moderate levels of abuse to explore any noticeable changes that may be monitored during charge and discharge operations. The electrochemical techniques are supported with materials evaluations to further understand the impact of abusive conditions on the constituent materials.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.