High Elastic Properties Research Articles

Plastification of Сarbon-Filled Polyetherimide

The article presents the results of the study of the possibility of plasticization of carbon-filled polyetherimide (PEI). Oligophenylene sulfone (OPSU) and polycarbonate (PC) were used as plasticizing agents. It is shown that OPSU and PC have a rather effective plasticizing effect during processing. Moreover, their introduction improves the elastic-strength properties of carbon fibres-filled PEI. It is revealed that composites with OPSU have a higher heat resistance and thermal oxidative stability of the melt. Samples of carbon-filled PEI containing plasticizer, printed by FDM, showed high elastic properties.

Investigation of mechanical and radiation shielding features of heavy metal oxide based phosphate glasses for gamma radiation attenuation applications

In this study, xPbO2 − [(100 − x)(0.5Na2O − 0.5P2O5)] glass samples where x = 0, 5, 10, 15, 20 and 30 mol%, were prepared and their radiation shielding and mechanical properties were investigated. A 3 × 3 inch NaI (Tl) scintillation detector has been used to detect the emitted gamma-ray. The obtained results revealed the increase of both PbO2 content and the photon energy from 0.356 to 1.33 MeV increase the mass attenuation coefficient (MAC), the effective atomic number (EAN), and the radiation protection efficiency (RPE) and in the same time decrease the values of the half-value layer (HVL) and the mean free path (MFP). The G-P fitting method was used to calculate the exposure buildup factor in the photon energy range of 0.015–15 MeV along with the use of SRIM code, ESTAR database and the removal cross-sections to calculate the proton, alpha and electron mass stopping power of the prepared glasses. These parameters are affected mainly with Zn (n = 2 or 4). Moreover, the elastic properties of the glass samples have been calculated by measuring both longitudinal (VL) and shear (VS) velocities using the pulse-echo overlap technique at 5 MHz. The sample that had 30 PbO2 mol% had the highest elastic properties that gives confidence in the possibility of using these glasses for radiation shielding application.

Mechanical properties and curing characteristics of shape memory natural rubber

Natural rubber, which is a polydiene elastomer, is one of the attractive raw materials that could be developed as a shape memory polymer because of its high mechanical and elastic properties. This study aims to determine mechanical properties and curing characteristics of heat-induced shape memory polymer of natural rubber or herein after referred to shape memory natural rubber (SMNR). Natural rubber with different blend ratios of sulphur was prepared by a two-roll mill. The curing characteristics were determined using Moving Die Rheometer at 150°C. The effect of sulphur (0.75; 1.25; 1.5 phr) on mechanical properties such as tensile strength, tear strength and shape memory properties of the stearic acid swollen SMNR vulcanizates were investigated. This research showed that the higher sulphur amount gives the higher torque difference and higher mechanical properties. Shape memory compound swollen stearic acid exhibited shape recovery of 98-100% and shape fixity 59-88.5%.

New, Effective, and Low-Cost Dual-Functional Binder for Porous Silicon Anodes in Lithium-Ion Batteries.

In this work, a neweffective and low-cost binder applied in porous silicon anode is designed through blending of low-cost poly(acrylic acid) (PAA) and poly(ethylene- co-vinyl acetate) (EVA) latex (PAA/EVA) to avoid pulverization of electrodes and loss of electronic contact because of huge volume changes during repeated charge/discharge cycles. PAA with a large number of carboxyl groups offers strong binding strength among porous silicon particles. EVA with high elastic property enhances the ductility of the PAA/EVA binder. The high-ductility PAA/EVA binder tolerates the huge silicon volume variations and keeps the electrode integrity during the charge/discharge cycle process. EVA colloids acting as host materials for electrolytes increase the electrolyte uptake of electrodes. The porous silicon electrode with the PAA/EVA binder exhibits a reversible capacity of 2120 mA h g-1 at 500 mA g-1 after 140 cycles because of the excellent ductility and lithium-ion transport properties of the PAA/EVA binder.

Polyurethane/Siloxane Hybrid Polymers with Chemiluminescent Mechanophores as Stress Probes

AbstractA series of mechanoluminescent polyurethane/siloxane hybrid polymers are synthesized through mild polycondensation and sol–gel hydrolysis process with 1,2‐dioxetane as the mechanophore. With joint advantages of polyurethanes and silicon‐containing polymers, these hybrid polymers exhibit good mechanical strength, high elasticity, and water resistance properties. Herein, 1,2‐dioxetane acts as an autoluminescent probe of chain scission, which could emit visible and sensitive signals of the covalent bond breaking in these hybrid polymers under mechanical force. Thus, chain scission and chain slipping events during the failure process of these polymers can be effectively discriminated. The current work will offer exciting opportunities to study the failure process of hybrid polymers with unprecedented temporal and spatial resolutions.

A Series of MAX Phases with MA-Triangular-Prism Bilayers and Elastic Properties.

We report a new type of MAX phase (M=transition metals, A=main group elements, and X=C/N), Nb3 As2 C, designated as 321 phase. It differs from all the previous Mn+1 AXn phases in that it consists of an alternate stacking of one MX layer and two MA layers in its unit cell, while only one MA layer is allowed in usual MAX phases. The new 321 phase exhibits a bulk modulus of Nb3 As2 C up to 225(3) GPa as determined by high-pressure synchrotron X-ray diffraction, one of the highest values among MAX phases. Isostructural 321 phases V3 As2 C, Nb3 P2 C, and Ta3 P2 C are also found to exist. First-principles calculations reveal the outstanding elastic stiffness in 321 phases. Among all 321 phases, Nb3 P2 C is predicted to have the highest elastic properties. These 321 phases, represented by a chemical formula Mn+1 An X, were added as new members to the MAX family and their other properties deserve future investigations.

A Series of MAX Phases with MA‐Triangular‐Prism Bilayers and Elastic Properties

AbstractWe report a new type of MAX phase (M=transition metals, A=main group elements, and X=C/N), Nb3As2C, designated as 321 phase. It differs from all the previous Mn+1AXn phases in that it consists of an alternate stacking of one MX layer and two MA layers in its unit cell, while only one MA layer is allowed in usual MAX phases. The new 321 phase exhibits a bulk modulus of Nb3As2C up to 225(3) GPa as determined by high‐pressure synchrotron X‐ray diffraction, one of the highest values among MAX phases. Isostructural 321 phases V3As2C, Nb3P2C, and Ta3P2C are also found to exist. First‐principles calculations reveal the outstanding elastic stiffness in 321 phases. Among all 321 phases, Nb3P2C is predicted to have the highest elastic properties. These 321 phases, represented by a chemical formula Mn+1AnX, were added as new members to the MAX family and their other properties deserve future investigations.

Study on Microstructure and Properties of Cu-9Ni-6Sn Alloy Applied for Electric Measurement

High strength elastic alloy has an important role in the manufacture of electrical equipment and machine building. Along with the development of information and telecommunications technology, the application of this alloy in electrical and electronic equipment is very increasingly. Even on boards or connectors of common electrical equipment such as computers, cell phones, these connectors are usually made of high strength elastic copper alloy. The design required features are small, precision built, with high mechanical strength and elasticity, heat resistance, abrasion and corrosion resistance in the operating environment to ensure its/the power and signal stability for a long time. The design trend is reduced in size but still assure the equipment quality is growing significantly and the corporation to manufacture equipment is researched thoroughly. Accordingly, this article presents the research results about the alloy copper with 9%Ni and 6%Sn which has the high elastic strength and elasticity properties of elastomers after heat treatment. The properties of the microstructure, hardness, conductivity, dry friction coefficient, the corrosion resistance of the alloy from which to determine the parameters for the materials selection procedure and the design of the manufacturing of magnetic contact of this alloy. The results of the study show that after heat treatment and deformation, the Cu-9Ni-6Sn has a strength of alloy up to 1200MPa, the elastic limit is 1100MPa and the conductivity is 8.4%IACS, respectively. The values ​​of this characteristic are consistent with the working conditions of the electrical contact. With the deformation process combined with the heat treatment process, the results of our research group created a single-phase homogeneous microstructure that is chemically stable with the spinodal decomposition in appropriate to the treatment of aging process. By modern methods, this paper demonstrates the durability of the alloy due to the spinodal decomposition during aging treatment at 350°C. This structure of spinodal decomposition is about 20-40nm in size, dispersed throughout the entire cross-section of the sample.

Air‐Stable Symmetric Ambipolar Field‐Effect Transistors Based on Reduced Graphene Oxide‐OTS Self‐Assembled Monolayer Heterostructure

AbstractGraphene has attracted great interest in the past decade due to its unique band structure and physical properties such as quantum electronic transport, extremely high mobility, high elasticity and optical properties. Graphene is generally obtained by mechanical exfoliation, epitaxial growth, chemical vapor deposition and chemical synthesis approaches, wherein the reduction of graphene oxide (GO) is a practical approach to synthesize large‐scale graphene. Via reduction, highly conductive reduced graphene oxide (RGO) can be obtained, which has electrical and optical properties analogous to those of graphene. However, Field‐effect transistors (FETs) based RGO typically exhibit p‐type in ambient rather than the ambipolar behavior of intrinsic graphene, due to the doping effect induced by substrate and the air. Meanwhile, large hysteresis accompanies with the p‐type transistor. Here, a self‐assembled monolayer (SAM) of octadecyltrichlorosilane (OTS)‐RGO heterostructure is developed, in which RGO is sandwiched between OTS SAMs. The heterostructure passivates the RGO device and eliminates the doping of graphene from the surroundings. The obtained RGO FETs exhibit air‐stable symmetric ambipolar behavior with Dirac point at 0 V gate voltage and negligible hysteresis. This approach will also be applicable to pristine graphene and other two‐dimensional materials to obtain the intrinsic properties under ambient conditions, thereby promoting the research and applications of two‐dimensional materials.

Facile fabrication of elastic CoO@graphene aerogel for recycled degradation of chloramphenicol

Graphene aerogel with well-distributed CoO nanoparticles (CoO@GA) has been subtly fabricated by using methylamine as a multifunctional agent through hydrothermal and calcination processes for the degradation of chloramphenicol (CAP). The results showed that CoO@GA containing 27.3 wt% of CoO nanoparticles with size ranging from 30 to 60 nm exhibited high mechanical elastic property. The cyclic compression testing with strain up 50% showed CoO@GA can completely recover to its original form after compression. Compared with bare CoO, Co2+ or GA, CoO@GA performed the best degradation efficiency for CAP (95.8%) in the presence of peroxymonosulfate (PMS). Quenching experiment indicated HO and O2− were the main active radicals generated in the CoO@GA-PMS system. The recycled experiments showed CoO@GA had stable efficiency (above 82.8%) within 9 times for the degradation of CAP.

Dynamics of lubricious, concentrated PMMA brush layers studied by surface forces and resonance shear measurements

We employed surface forces and resonance shear measurement (RSM) for studying the structure and properties of typical concentrated polymer brushes (CPBs) of poly(methylmethacrylate) (PMMA) in toluene, which are known to show very low friction. The surface forces measured between the silica surfaces bearing PMMA brush layers showed a steric repulsive force at distances between the silica surfaces of less than ca. 1050 nm (Donset). Upon retraction after compression of the PMMA brush layers, no adhesive force was observed. This indicated that the interpenetration of the polymer chain was not induced by the normal load. Based on the resonance shear measurement, the elastic (k2) and damping (viscous) (b2) parameters, which represent the dynamic properties, of the PMMA brush layers were obtained by analyzing the resonance curves. At distances below the Donset, the b2 value significantly increased and slightly decreased at the higher normal loads, and the k2 value monotonically increased with increasing load. These k2 and b2 values were greater than those obtained for a PMMA brush layer and a bare silica surface (PMMA-silica). This indicated that the mobility of the polymer chains for the PMMA-PMMA brush layers was more suppressed compared to that for the PMMA-silica, due to the interpenetration of the polymer chains. The interpenetration of the polymer chains, commonly not observed for CPBs, could be most probably induced by the application of both the normal load and oscillating shear motion. With increasing shear amplitude on the compressed PMMA-PMMA brushes (at L = 0.84, 1.34 and 4.28 mN), the b2 value first increased then decreased whilst the k2 value monotonically decreased. These tendencies can be explained by the change from the sticking condition due to interpenetration (high k2), small sliding under interpenetration (increase in b2, decrease in k2), and then smooth sliding by pulling out of interpenetrated polymer chains (decrease in b2 and k2). The obtained results indicated that the operating conditions are quite important for using polymer brush layers as tribological materials because they can exhibit both a high and low friction depending on the conditions such as the load and shear amplitude.

Properties of concrete using crumb rubber and rice husk ash as additive for rigid pavement material in peat environment

A waste tyre is an inorganic rubber waste that is difficult to decompose since it has a complex structure. Utilization of waste tyre as a material to improve elastic properties in rigid pavement construction in peat environment has not investigated yet. The rigid pavement in peat environment needs to be impermeable and posses high elastic properties. This paper presents mechanical properties and porosity of concrete incorporating crumb rubber as an additive in concrete mixture with a variation of 10%, 20%, and 30% by fine aggregates volume. Rice husk ash is added as a filler in various percentage (5%, 10%, and 15%) by cement volume in the mixture. Concrete is produced with a target strength of 35 MPa. In this research, the OPC concrete mix is used as a control mix. Mechanical properties taken were the compressive strength, tensile strength, flexural strength, modulus of elasticity, and porosity at 7, 14 and 28 days. Results show that crumb rubber and rice husk ash addition increases compressive strength, improves elastic properties, i.e., tensile strength, flexural strength, modulus of elasticity, and reduce the porosity of the concrete. It can be concluded that the crumb rubber is potential as an environmentally friendly additive as rigid pavement material in peat environment.

PMB quality problems based on its morphology and used equipment

In the first part of the study, a direct relationship is established between the influence of the morphology of PMB (polymer modified binder) on the totality of its consumer properties and its tendency to destruction. The second part of the study is devoted to the influence of technological equipment used for the production of polymer modified binder on its properties. It was experimentally established that having the same initial components, PMB of completely different quality were obtained at the output. According to the degree of increase in rigidity (penetration value at 25 °C), obtained PMBs can be conditionally positioned as follows: prepared using a paddle mixer, a colloid mill, and an extruder. It is proved that the high elastic properties of PMB can be achieved by using paddle mixers that do not damage the long polymer macromolecules during the process. However, such binders are prone to delamination. To eliminate this negative aspect, the use of additional crosslinking agents is necessary. PMB prepared using an extruder has lost its elastic abilities, has become tough, with a high rate of cohesive strength. Thus, it is noted that when designing PMB compositions, it is necessary to carefully choose not only the raw material base but also the technological equipment for its preparation.

Steel plate shear wall – a 20th century review

This paper provides a brief summary carried out in past analytical and experimental research work on steel plate shear walls with empha- sis given up to 20th Century. In buildings, two different systems exist to resists the loads viz., gravity load system and a lateral load sys- tem. To transfer the vertical loads to the footing gravity load system is used while lateral loads due to wind and seismic loads are resisted by the Lateral Load Resisting System (LLRS). Steel Plate Shear Walls (SPSW) is relatively a new type of LLRS; it has many distinct performance benefits including large displacement ductility capacities, high elastic stiffness properties, and stable hysteresis behavior as compared to other LLRS. The experimental results were also compared with simplified analytical models. The capacity of SPSW is li- mited to elastic buckling strength of its plate panels. This practice results not only in an undesirable one, but also in a conservative design, where columns buckle and may yield before the plate reaches a fraction of its capacity. With failure plate buckling is not synonymous and along its boundaries if plate is supported adequately, as in the case of SPSW the post buckling strength may be several times theoret- ical buckling strength.

High Frequency Elastic Properties of Nitride Nanowires-Based Structures

The present research aims at studying the elastic properties of III-Nitride nanowires (NWs) embedded in HSQ matrix, capable to efficiently convert the mechanical energy into electricity. We report on elastic properties of such novel nano-engineered functional materials studied by using “transient grating” acoustic experiment.

Increased myocardial stiffness activates cardiac microvascular endothelial cell via VEGF paracrine signaling in cardiac hypertrophy

When the heart is subjected to an increased workload, mechanical stretch together with neurohumoral stimuli activate the “fetal gene program” and induce cardiac hypertrophy to optimize output. Due to a lack of effective methods/models to quantify and modulate cardiac mechanical properties, the connection between these properties and the development of cardiac hypertrophy remains largely unexplored. Here, we utilized an atomic force microscope (AFM) to directly measure the elastic modulus of the hypertrophic myocardium induced by pressure overload. Additionally, we investigated the effects of extracellular elasticity on angiogenesis, which provides blood and nutrition to support cardiomyocyte hypertrophic growth in this process. In response to pressure overload, the myocardium rapidly developed hypertrophy and correspondingly demonstrated a high elastic modulus property. This mechanical feature correlated with enhanced angiogenesis. Mechanistically, we found that a high elastic modulus promoted cultured cardiomyocytes to synthesize and paracrine vascular endothelial growth factor (VEGF) to activate cardiac microvascular endothelial cells. Further analysis showed that the increased elastic modulus enhanced the interaction between Talin1 and integrin β1 to activate the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (Hif-1α) pathway, which contributed to VEGF production. Thus, our study revealed a critical role of the elastic modulus in regulating angiogenesis during the development of cardiac hypertrophy.

High pressure structural, elastic and electronic properties of a new half Heusler compound: AuYPb

In the present paper, the electronic, structural and elastic properties of AuYPb have been explored utilizing density functional theory (DFT) within the generalized gradient approximation (GGA). The transition of AuYPb from face cantered cubic structure (FCC) to the hexagonal structure is performed considering the hybrid exchange correlation PBE practical approach. The structural phase transition, volume collapse of AuYPb is figured. The elastic properties are also investigated in the most stable structure of present Heusler alloy. Our estimated values of Poisson's ratio and Pugh ratio confirm the ductile nature of AuYPb. The electronic band structure (BS) and density of states (DOS) of cubic and hexagonal phases are likewise detailed. Almost all the investigated properties for present alloy are new and present for the first time.

Application of 4T-PET fibers/nonwovens for leucocyte filters

Polyethylene terephthalate (PET) fiber with four T-lobe cross section (4T-fiber) has been applied to textile products due to the structural characteristic of micro-grooved channels to provide the high wicking, warming, and elastic properties. In this study, nonwoven (NW) filters composed of one layer of 4T-PET NW (containing 65% 4T-fibers) with one, three, or five layers of polypropylene (PP) NW (4T-PET NW + PP NW × 1, 3, or 5) were proposed for blood filtration to remove leucocytes to reduce blood transfusion-related adverse reactions. The removal rate of leucocytes could be enhanced when the PP NW layers were increased. The presence of the 4T-PET NW on the surface of five layers of PP NW (4T-PET NW + PP NW × 5) filters resulted in a higher erythrocyte recovery rate without losing the capability to remove leucocytes and platelets. Based on the theoretical analysis, leucodepletion filters were further prepared by stacking four 4T-PET NW + PP NW × 5 units together. The optimum filtration results of the filters for filtrating 110 mL of red blood cell concentrates could be prepared when four units of 4T-PET NW + PP × 5 NW placed in a series combination.

The effect of plasticization on the properties of poly(urethaneureas) based on oligoether diols, 2,4-toluenediisocyanate, and aromatic diamines

Segmented poly(urethaneureas) (SPUUs) modified with low glass transition temperature chemically inert liquids are of interest due to their controllable properties and potential applications under various environmental conditions. Investigation into the influence of plasticizers on the properties of SPUUs based on oligotetramethyleneoxide diol (polytetramethyleneoxide), oligopropyleneoxide diol (polypropyleneoxide), 2,4-toluenediisocyanate, Ethacure-300, and methylene-bis- o-chloroaniline was conducted. Partial crystallization of polytetramethyleneoxide segments was identified during cooling of some SPUU samples plasticized by di-(2-ethylhexyl)sebacate (DEHS) and tributyl phosphate. Polypropyleneoxide segments did not crystallize under the same conditions. A low crystallization temperature for the amorphous component of the polymer matrix in SPUU (−100°C to 103°C) was attained at a molecular mass ( Mn) of soft segments equal to 2000 g mol−1 and a DEHS concentration equal to 40–45%. A relationship between the mechanical properties of plasticized SPUU, microphase segregation, and dilution of the polymer matrix was found. For the first time, the effect of dilution with plasticizer on the strength of elastomers was considered. The plasticization effect on the mechanical properties of SPUU was investigated in the temperature diapason from 50°C to −70°C. The results of these investigations can be used in various technologies including the design of SPUUs with high elastic properties at temperatures as low as −70°C, typical of extreme conditions of the Arctic climate.

Progress in understanding of deformation mechanism of polyolefin elastomers during tensile stretching

Polyolefin elastomer is a kind of polyolefin product with excellent performance. Based on its high elasticity properties and impact resistance as well as easy processing, the polyolefin elastomer is widely used in adhesive, mixture, films and nonwoven. The relationship between the microstructure and mechanical behavior in polyolefin is very close. Thus the investigation of “structure-property” relationship gives theoretical evidence in understanding the mechanical behavior. The research progress in understanding of the deformation mechanism during tensile tests for polyolefin elastomer during last ten years is discussed.