High Elastic Properties Research Articles

Arachnoidal cyst of the brain with post-traumatic hemorrhage: case report and literature review

Introduction. Arachnoid cysts (AC) occur in 1-3% of children. There is sacs with spinal fluid between brain and arachnoid membrane. Only about 6% of intracranial AC manifest clinically. AC can be complicated by hemorrhage with traumatic brain injury and spontaneously. Materials and methods. We have described a clinical case of AC, complicated by hemorrhage with the subdural hematoma after brain injury and literature review. There is unusually that after drainage of the hematoma, complete resolution of the AK was noted (the only such case described in the literature). Conclusion. The asymptomatic AC can be complicated by hemorrhage due brain injury or spontaneously. Due to the high elastic properties of the brain in children, complete regression of even long-existing AC is possible.

Citronella Oil as Additives in Active Carrageenan -based Food Packaging Films: A Review

The natural degradation process of plastics is slow and harmful to the environment, making biodegradable films a more advantageous option. These films not only reduce environmental pollution but also have the potential to preserve food products and extend their shelf life. This study explores the potential of utilizing iota carrageenan-based films in combination with essential oils for food packaging applications. Iota carrageenan, known for its high elasticity and thixothrophic properties, serves as an ideal base material for film formation. Essential oils, with antioxidant and antimicrobial properties, are incorporated into the packaging material to enhance shelf life and prevent food spoilage. Citronella oil demonstrates effective antimicrobial and antioxidant activities for food preservation. The presence of essential oils acts as plasticizers in the film, improving flexibility but requiring careful consideration of concentration to maintain network strength.

Mobility and Method of Enhanced Oil Recovery for Yingxiongling Shale Oil

Abstract There are abundant shale oil resources in Yingxiong Ling, Qaidam Basin, but the oil recovery rate is low due to complex lithofacies types, large physical property differences, diverse pore types and structures, and strong heterogeneity. In order to improve the oil recovery efficiency of Yingxiong Ling shale oil, based on the analysis of the factors affecting the micro-mobility of Yingxiong Ling shale oil, through spontaneous imbibition and nuclear magnetic test, the oil mobility evaluation of different lithology reservoirs and different pore structures and the feasibility of surfactant to improve oil recovery were carried out. The research results show that: (1) Yingxiong Ling shale oil has considerable mobile hydrocarbon base, effective seepage channels, high viscosity reduction conditions and elastic properties, and has the potential for efficient development. (2) In the spontaneous imbibition state, the utilization efficiency of laminar limestone and laminar limestone are 10% and 12.5%, respectively, and that of small pores, large pores and texture cracks are 6.7%, 5.2% and 1.8%, respectively. The overall utilization efficiency is low. (3) The solution containing surfactant components can effectively improve the crude oil production degree of Gan Chaigou shale oil reservoir. The variable-viscosity fracturing fluid can increase the oil production efficiency to 21.46%, and the nano-emulsion can increase the oil production efficiency to 33.43%. The surfactant has a significant effect on the EOR of Yingxiong Ling shale oil. Based on the analysis of micromobility, the characteristics of crude oil mobility and the experimental results of enhanced oil recovery by surfactants, it is concluded that the oil recovery of Yingxiong Ling shale oil can be greatly improved by combining high efficiency surfactants with large-scale volumetric fracturing.

Multifunctional conductive SA/ATO@TiO2 whisker aerogels for piezoresistive pressure sensor application

Ultralight and flexible aerogel sensors have garnered significant interest, yet challenges persist in developing their high elasticity and exceptional piezoresistive properties. In this work, laminated porous composite aerogels have been successfully prepared by a composite of sodium alginate (SA) and antimony-doped SnO2 coated titanium dioxide whiskers (ATO@TiO2) via directional freezing technique. The resulting SA and ATO@TiO2 (SAT) aerogels with laminated porous structure demonstrate lightweight with low-density (0.06 g·cm−3), good compressive properties, superplastic, and conductive properties. The incorporation of small amounts of rod-like ATO@TiO2 whiskers into SAT aerogels not only enhances its electrical conductivity and thermal insulation, but also imparts a light-colored appearance to the aerogel. The assembled SAT aerogel sensors exhibit high sensitivity within 1.0 kPa (225 kPa−1, 17.86 kPa−1) and maintains excellent fatigue resistance even over 1000 cycles. The temperature-responsive properties of SAT aerogel sensors presented superior thermal insulation properties, and it can operate properly even at a high temperature of 100 °C. More importantly, SAT piezoresistive sensors facilitated real-time monitoring and human-computer interactive activities related to human movement and health, showcasing significant potential in diverse fields.

CO2 derived ABA triblock all-polycarbonate thermoplastic elastomer with ultra-high elastic recovery

Although triblock polycarbonate thermoplastic elastomers (TPEs) have recently attracted great interests due to their biodegradability, insufficient attentions have been paid to improving the elastomeric properties. Through a tandem reaction strategy involving CO2 / allyl glycidyl ether (AGE) / cyclohexene oxide (CHO), poly(cyclohexene carbonate)-b-poly(allyl glycidyl ether carbonate)-b-poly(cyclohexene carbonate) (PCAC) is successfully synthesized using a metal-free Lewis acid-base pair catalyst. The synthesized PCACs are pure well-defined ABA triblock all-polycarbonate, which is supported by 1H NMR, gel permeation chromatography (GPC), and diffusion-ordered spectroscopy (DOSY). A simple modification by grafting alkylthiol chains to PCAC results in excellent TPEs named PCAC-g-S-CaH2a+1 (PCASaC). The synthesized TPEs are characterized by atomic force microscopy (AFM), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and mechanical test. They demonstrate a semi-network and semi-domain phase separation structure, wide service temperature range, good strength, high elongation, and extremely high elastic recovery properties. This low-cost, biodegradable, high-performance TPE shows great potential for applications in biomedical, wearable products, sports equipment, and other fields.

Experimental and numerical investigation on the elastic properties of luffa–cenosphere‐reinforced epoxy hybrid composite

AbstractEstimating the elastic characteristics of natural fiber‐reinforced polymer composites such as luffa fiber reinforced with epoxy is challenging. The structure of luffa cylindrica is complex, like a three‐dimensional natural fibrous mat, netting‐like structure. The multiscale modeling of such structures is the challenge to be addressed. The prime objective of this work is to determine the specific elastic properties of luffa–cenosphere‐reinforced epoxy (LCE) composite, considering the effect of filler volume fractions. Furthermore, multiscale modeling techniques, such as representative volume elements (RVEs) of finite element techniques with chopped, unidirectional, plain, and twill weaving fiber arrangements, were employed. The longitudinal modulus, transverse modulus, shear modulus, and Poisson's ratio were predicted through these modeling approaches. However, experimental and analytical methodologies, including the rule of mixture and Halpin–Tsai, were considered to validate the finite element analysis results. The elastic characteristics of LCE composite were therefore shown to be enhanced by increasing filler volume fraction. However, the cenosphere's 20% volume fraction has the highest elastic properties as determined by analytical, experimental, and computational models. Analytical and finite element simulation results were compared with the experimental results, and based on the findings, the most suitable (unidirectional, chopped, plain, and twill weaving) RVE was identified for finite element modeling of LCE composite for the evaluation of elastic properties. Results from practical approaches and the RVE twill weaving model showed good agreement, with less than 1% error, compared to the other analytical and finite element methods.Highlights NFCs are gaining ground in polymer composites. Overcoming challenges in modeling of luffa fiber inside epoxy matrix. The study uses multiscale modeling with diverse fiber arrangements. Experimental and analytical methods used to confirm FEA results. Increased cenosphere volume fraction boosts LCE composite properties.

High Barrier Properties of Butyl Rubber Composites Containing Liquid Rubber and Graphene Oxide.

The high elasticity and excellent gas barrier properties of rubber composites make them irreplaceable in the field of sealing. Constructing a complicated barrier network to reduce free volume is crucial to improving gas barrier properties. In this research, liquid acrylonitrile-butadiene rubber/γ-Methacryloxypropyl trimethoxy silane (KH570) modified graphene oxide/butyl rubber composites (LNBR/KGO/IIR) were fabricated. A KGO lamellar network was constructed to resist gas diffusion in the IIR matrix. Meanwhile, LNBR macromolecules further occupied the free volume inside the IIR composites, thereby maximizing the retardation of the path of small molecule gas permeation. The modification of GO by KH570 was successfully demonstrated through FTIR and XRD. The grafting rate of KH570 was calculated to be approximately 71.4%. KGO was well dispersed in IIR due to emulsion compounding and the formation of lamellar networks. The 300% modulus, tensile strength and tear strength of KGO/IIR were improved by 43.5%, 39.1% and 14.8%, respectively, compared to those of the IIR composite. In addition, the introduction of LNBR resulted in a 44.2% improvement in the gas barrier performance of nitrogen permeability relative to the original IIR composite.

Preparation of highly elastic superhydrophobic CNF/Fe3O4 based materials modified in aqueous phase for oil-water separation

Magnetic superhydrophobic materials have broad application prospect in oil-water separation. In this study, a magnetic and superhydrophobic aerogel with lamellar structure was successfully prepared using cellulose nanofibrils (CNF) as the skeleton, Fe3O4 as the magnetic ion, 1H, 1H, 2H, 2H trialkylfluorooctane triethoxysilane (FS) and 3-(2-aminoethyl amino)-propyl trimethoxysilane (AS) as the combined modifier. The prepared aerogel shows lower density (38.63 mg/cm3), excellent magnetic (15.13 emu/g), high elasticity and good oil sorption properties (21 g/g). In addition, FS/AS also exhibits excellent mechanical properties and superhydrophobic ability (water contact angle (WCA) of 151.9 ± 1.4°), as it provides sufficient toughness and low surface energy for the layer-branch structure. It should be noted that the entire preparation process is carried out in the aqueous phase, without the use of any organic solvents, providing a green oil-water separation strategy.

Stereolithographic Process for Embedding of Electronic Components into Multi-material Flexible and Stretchable Polymer Substrate to Reduce Stress During Stretching

The integration of rigid electronic components into stretchable materials is a complex challenge due to contrary material properties. This paper shows a novel approach for the embedding of electronic components into flexible and stretchable polymer substrates using a stereolithographic process that leads to stress reduction during stretching. The key factor is the multi-material printing with various elastic material properties. The paper shows a miniaturized packaged component (e.g. 0201 LED) in a flexible and stretchable substrate based on three different materials. The first material has rigid properties (stiffness 42.25 N/mm) and surrounds a small area of the LED with about 500 μm peripheral frame. The main purpose of this material is to round up the sharp edges of the LED to the next material. The second material is more elastic (stiffness 0.11 N/mm) and surrounds the first embedded LED. The purpose of the implementation of the second intermediate material is to spread the load between the LED and stretchable substrate caused by stretching. The third material has even higher elastic properties (stiffness 0.05 N/mm) and builds up the main part of the stretchable substrate (size of (4.5x34) mm2). After the fabrication of the multi-material substrate with the embedded LED, horseshoe conductive traces are screen printed with conductive paste. Finally, the embedded LED substrate with the conductive traces is cured at 125 °C. The final stretchable substrate with the embedded LED was able to stretch up to about 25 % for 30 cycles without disturbing the electrical function.

Stereolithographic Process for Embedding of Electronic Components into Multimaterial Flexible and Stretchable Polymer Substrate to Reduce Stress During Stretching

The integration of rigid electronic components into stretchable materials is a complex challenge due to contrary material properties. This paper shows a novel approach for the embedding of electronic components into flexible and stretchable polymer substrates using a stereolithographic process that leads to stress reduction during stretching. The key factor is multimaterial printing with various elastic material properties. The paper shows a miniaturized packaged component (e.g., 0201 LED) in a flexible and stretchable substrate based on three different materials. The first material has rigid properties (stiffness 42.25 N/mm) and surrounds a small area of the LED with about 500 mm peripheral frame. The main purpose of this material is to round up the sharp edges of the LED to the next material. The second material is more elastic (stiffness 0.11 N/mm) and surrounds the first embedded LED. The purpose of the implementation of the second intermediate material is to spread the load between the LED and stretchable substrate caused by stretching. The third material has even higher elastic properties (stiffness 0.05 N/mm) and builds up the main part of the stretchable substrate (size of (4.5 3 34 3 0.27) mm3). After the fabrication of the multimaterial substrate with the embedded LED, horseshoe conductive traces are screen printed with conductive paste. Finally, the embedded LED substrate with the conductive traces is cured at 125 degrees C. The final stretchable substrate with the embedded LED is able to stretch up to about 25% for 30 cycles without disturbing the electrical function.

Thermally stable C2-symmetric α-diimine nickel precatalysts for ethylene polymerization: semicrystalline to amorphous PE with high tensile and elastic properties.

In α-diimine nickel catalyst-mediated ethylene polymerization, adjusting catalytic parameters such as steric and electronic factors, as well as spectator ligands, offers an intriguing approach for tailoring the thermal and physical properties of the resulting products. This study explores two sets of C2-symmetric α-diimine nickel complexes-nickel bromide and nickel chloride-where ortho-steric and electronic substituents, as well as nickel halide, were varied to regulate simultaneously chain walking, chain transfer, and the properties of the polymers produced. These complexes were activated in situ with Et2AlCl, resulting in exceptionally high catalytic activities (in the level of 106-107 g (PE) mol-1 (Ni) h-1) under all reaction conditions. Nickel bromide complexes, with higher ortho-steric hindrance, exhibited superior catalytic activity compared to their less hindered counterparts, whereas the reverse was observed for complexes containing chloride. Increased steric hindrance in both sets of complexes facilitated higher polymer molecular weights and promoted chain walking reactions at lower reaction temperature (40 °C), while the effect became less pronounced at higher temperature (100 °C). However, the electron-withdrawing effect of ortho-substituents hindered the rate of monomer insertion, chain propagation, and chain walking reactions, leading to the synthesis of semi-crystalline polyethylene with an exceptionally high melt temperature of 134.6 °C and a high crystallinity of up to 31.9%. Most importantly, nickel bromide complexes demonstrated significantly higher activity compared to their chloride counterparts, while the latter yielded polymers with higher molecular weights and increased melt temperatures. These high molecular weights, coupled with controlled branching degrees, resulted in polyethylenes with excellent tensile strength (up to 13.9 MPa) and excellent elastic properties (up to 81%), making them suitable for a broad range of applications.

Dynamics of the warp beam brake drive on a weaving loom for the production of natural silk fabrics

In the process of producing silk fabrics, by the fact of the high elastic properties of the threads large relaxation oscillations occur in the weaving system of the loom. Therefore, it is advisable to equip looms for the production of silk fabrics with brake regulators, and the rest of the range of fabrics with main regulators. On the basis of a mechanical model of relaxation oscillations and the scheme of a braking regulator for this model the regularities of friction force change depending on the duration of immovable contact and spring tension in time are obtained. The friction force for long contact time, zero contact time and contact time are determined. The mode against rotation of a driving disk causes stability of braking in a frictional pair.

Co-continuous structure enhanced magnetic responsive shape memory PLLA/TPU blend fabricated by 4D printing

ABSTRACT Combining poly (L-lactic acid) (PLLA) with thermoplastic polyurethane elastomer (TPU) can integrate the advantages of excellent biocompatibility and intrinsic shape memory ability of PLLA and high elasticity and excellent shape memory properties of TPU in the application of minimally invasive surgery for bone tissue engineering. However, TPU easily forms a sea-island-like structure in PLLA matrix, decreasing shape memory properties. In this study, a co-continuous structure of TPU phase in PLLA matrix was constructed by adding Fe3O4 nanoparticles due to the changed interfacial tension and flow behavior of TPU, which endowed the TPU/PLLA/Fe3O4 blend fabricated via selective laser sintering (SLS) with excellent shape memory properties. As a result, the morphology of TPU in the blend changed from sea-island-like structure to complete co-continuous structure with increasing Fe3O4 content (0 to 10wt%), and shape recovery ratios in 50 °C water increased from 66.67 to 95.92%. The introduction of Fe3O4 endowed the blend with magnetic responsive shape memory in alternating magnetic field because Fe3O4 could heat it by generating heat from relative friction and particle collisions. Besides, the tensile modulus and hardness of the specimen with 10wt% Fe3O4 nanoparticles increased. In addition, the blend demonstrated excellent biocompatibility by promoting cell adhesion, spreading, and proliferation.

HYBRID LAMINATE COMPOSITE CURVE STRUCTURE AS CYLINDRICAL CONCRETE COLUMN REINFORCEMENT

Composite materials are well known for their lightweight, easy to form, high elastic properties, and relatively low production costs. Laminated composites are composite materials that are widely applied in modern building structures such as aircraft walls, automotive cases, dashboards, press boards, etc. In this study, a curved laminated composite material was used as a reinforcing material surrounding the column structure. This study aims to analyze the mechanical strength of curved laminated composite materials as reinforcement for the cylindrical column concrete structure. Compressive testing of composite materials using the ASTM C39 standard. The materials used are jute fabric, e-glass, epoxy resin, and concrete aggregate. Specimens were molded using a vacuum bagging technique to minimize trapped air in the matrix. The curve shape of the laminated composite was obtained from the shape of the ASTM C39 concrete specimen with a diameter of 50 mm and a length of 150 mm. Based on the results of the study, the compressive strength of the structure increased up to 100% when the jute fabric was given up to 2 layers. Furthermore, the strength of the structure will increase up to 150% in the application of jute e-glass hybrid laminate composite.

Physical dynamic double-network hydrogels as dressings to facilitate tissue repair.

Double-network hydrogels can be tuned to have high mechanical strength, stability, elasticity and bioresponsive properties, which can be combined to create self-healing, adhesive and antibacterial wound dressings. Compared with single-network hydrogel, double-network hydrogel shows stronger mechanical properties and better stability. In comparison with chemical bonds, the cross-linking in double networks makes them more flexible than single-network hydrogels and capable of self-healing following mechanical damage. Here, we present the stepwise synthesis of physical double-network hydrogels where hydrogen bonds and coordination reactions provide self-healing, pH-responsive, tissue-adhesive, antioxidant, photothermal and antibacterial properties, and can be removed on demand. We then explain how to carry out physical, chemical and biological characterizations of the hydrogels for use as wound dressings, yet the double-network hydrogels could also be used in different applications such as tissue engineering scaffolds, cell/drug delivery systems, hemostatic agents or in flexible wearable devices for monitoring physiological and pathological parameters. We also outline how to use the double-network hydrogels in vivo as wound dressings or hemostatic agents. The synthesis of the ureido-pyrimidinone-modified gelatin, catechol-modified polymers and the hydrogels requires 84 h, 48 h and 1 h, respectively, whereas the in vivo assays require 3.5 weeks. The procedure is suitable for users with expertise in biomedical polymer materials.

Hyaluronic acid single-network hydrogel with high stretchable and elastic properties

Stretchable materials have demonstrated great interest in wearable or implantable applications. Most of the existing hydrogels with high stretchability characteristics are based on double networks, exhibit large hysteresis loops, and cannot recover after deformation due to permanent rupture of network. Elastic, biodegradable, and biocompatible hydrogels are desirable for wound dressing of joints with frequent motions or post-surgical healing of mobile tissues. Here, we show a simple strategy for the preparation of a hyaluronic acid (HA) single-network hydrogel that can be stretchable and highly elastic without the addition of other components/partners or complicated processes of preparation. Our strategy relies on the use of high Mw HA to create a chemical hydrogel in which densely entangled HA chains are tied together by a small number of covalent bonds. While the presence of covalent cross-links can prevent disintegration of the HA network, entanglements endow the hydrogel with high stretchability through transmission of tension along the length of the long HA chains. The stretching-relaxation cycles show negligible hysteresis and perfect recovery of material after the release of force. The diminution of Mw together with increasing the concentration or cross-linker amount leads to brittle hydrogels.

A stretch hardening self-assembly strategy inspired by natural rubber for degradable, recyclable and self-repairing polyurethane elastomers

How to develop polyurethane elastomer with excellent mechanical properties and quick repair ability under mild conditions still needs to be overcome and improved. The transformation from static amorphous structure to dynamic crystalline state is an important factor for natural rubber to obtain high elasticity and mechanical properties. Therefore, with the aim of strengthening the dynamic crystalline phase of polycarbonate, a kind of high-strength and fast self-healing polyurethane elastomer with dual-phase transformation function was prepared by molecular conformation design. After testing, the mechanical strength of the elastomer is about 47 MPa, and the fracture energy is about 216 J/m2. Under mild conditions, rapid self-repair can be achieved within 1000 minutes, and the repair efficiency is as high as 95%, which is far higher than that of previously reported high toughness materials. Through the microstructure test, it is found that ultimate tensile hardening strategy of elastomers is the key to obtain high mechanical properties. Loose amorphous structure endows the elastomer with excellent dynamic properties, which is conducive to the rearrangement of disulfide bonds in the structure, so that the elastomer can quickly self-repair in a short time. In addition, the elastomer is easy to recycle and biodegrade (the degradation rate is 30.4% at 35 days), which provides an excellent strategy for the design of a new generation of electronic skin carriers.

Effects of aging degradation and reactive reconstruction on the structure and properties of styrene–butadiene–styrene block copolymer

Achieving high-performance recycling of aged SBS modified asphalt will help promote the sustainable development of transportation infrastructure. The destruction of the SBS cross-linking network is an important reason for the deterioration of the performance of aged SBS modified asphalt. Scientific reconstruction of aged SBS cross-linked network is the key to achieving the performance recovery of aged modified asphalt. In this research, the evolution of chemical structure, molecular weight, thermodynamic properties, multiple stress creep recovery capability and rheological property of SBS during the process of aging degradation and reactive reconstruction were systematically investigated. The results showed that the molecular weight and creep recovery capability of SBS decreased sharply, and its complex modulus and phase angle exhibited a strong temperature and frequency dependence after aging. While the number average molecular weight of aged SBS increased by over 70% after reactive reconstruction, and its thermal-oxygen stability shown better performance as compared with that of fresh SBS. Meanwhile, the glass transition temperature of aged SBS was restored to −43.8℃ and −54.9℃ after reactive reconstructed by toluene diisocyanate (TDI) and isocyanate pre-polymer. Therefore, isocyanate pre-polymer with flexible long chain structure was more benefit for improving the low-temperature performance of reactive reconstructed aged SBS. Furthermore, the creep recovery ability and complex modulus of aged SBS were all significantly improved, and exhibited dramatically high-elastic properties after reactive reconstruction. And as compared with isocyanate pre-polymer, TDI with benzene ring rigid structure was more conducive to restoring the medium–high temperature rheological properties of aged SBS. Therefore, effective restoration of molecular weight and performance of aged SBS can be achieved by using reaction reconstruction method. This study would provide inspiration and ideas for the high-value recycling of waste polymer modified asphalt.

Metal-Filled Polyvinylpyrrolidone Copolymers: Promising Platforms for Creating Sensors.

This paper presents research results on the properties of composite materials based on cross-linked grafted copolymers of 2-hydroxyethylmethacrylate (HEMA) with polyvinylpyrrolidone (PVP) and their hydrogels filled with finely dispersed metal powders (Zn, Co, Cu). Metal-filled pHEMA-gr-PVP copolymers in the dry state were studied for surface hardness and swelling ability, which was characterized by swelling kinetics curves and water content. Copolymers swollen in water to an equilibrium state were studied for hardness, elasticity, and plasticity. The heat resistance of dry composites was evaluated by the Vicat softening temperature. As a result, materials with a wide range of predetermined properties were obtained, including physico-mechanical properties (surface hardness 240 ÷ 330 MPa, hardness number 0.06 ÷ 2.8 MPa, elasticity number 75 ÷ 90%), electrical properties (specific volume resistance 102 ÷ 108 Ω⋅m), thermophysical properties (Vicat heat resistance 87 ÷ 122 °C), and sorption (swelling degree 0.7 ÷ 1.6 g (H2O)/g (polymer)) at room temperature. Resistance to the destruction of the polymer matrix was confirmed by the results concerning its behavior in aggressive media such as solutions of alkalis and acids (HCl, H2SO4, NaOH), as well as some solvents (ethanol, acetone, benzene, toluene). The obtained composites are characterized by electrical conductivity, which can be adjusted within wide limits depending on the nature and content of the metal filler. The specific electrical resistance of metal-filled pHEMA-gr-PVP copolymers is sensitive to changes in moisture (with a moisture increase from 0 to 50%, ρV decreases from 108 to 102 Ω⋅m), temperature (with a temperature change from 20 °C to 175 °C, ρV of dry samples decreases by 4.5 times), pH medium (within pH from 2 to 9, the range of ρV change is from 2 to 170 kΩ⋅m), load (with a change in compressive stress from 0 kPa to 140 kPa, ρV of swollen composites decreases by 2-4 times), and the presence of low molecular weight substances, which is proven by the example involving ethanol and ammonium hydroxide. The established dependencies of the electrical conductivity of metal-filled pHEMA-gr-PVP copolymers and their hydrogels on various factors, in combination with high strength, elastic properties, sorption capacity, and resistance to aggressive media, suggest the potential for further research as a platform for the manufacture of sensors for various purposes.

High temperature elastic properties of sub-stoichiometric yttrium dihydrides

Yttrium hydrides are considered as candidate materials for neutron moderation applied in microreactors (akin transportable miniaturized nuclear reactors) owing to their superior thermal stability and hydrogen retention. The evolution of elastic properties of these materials at elevated temperatures, needed for predicting the thermomechanical response and performance of the moderator during in-service reactor conditions, however, is lacking. Here, we report the Young’s and shear elastic moduli of three stoichiometries of bulk yttrium hydride (YHx, x = 1.61, 1.82, and 1.84) from room temperature to 1000 °C. In situ temperature-dependent measurements of the longitudinal and shear wave velocities were performed using a laser ultrasonic technique while heating the sample in a vacuum-pumped heating stage. The elastic moduli increased linearly with increasing hydrogen content and decreased by ∼10 % during heating from room temperature to 1000 °C in the three YHx compositions. The linear relationship between the elastic moduli and the hydrogen content in yttrium hydride was verified by atomistic calculations based on density functional theory (DFT). The absence of abrupt changes in the temperature-dependent measurements of elastic modulus of the YHx samples suggested negligible loss of hydrogen at elevated temperatures. Excellent agreement was found between the measured and calculated dependence of the elastic moduli on the stoichiometry, thereby providing a new approach for investigating the effects of fabrication-induced parameters (such as porosity) on the elastic moduli. This study demonstrates the utility of the combined approach involving DFT-based atomistic calculations and measurements of the elastic moduli for the informative development of metal hydrides and can be used as a metric for novel moderator materials investigations for emerging microreactors and beyond.