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Purpose: The current study aimed to determine the effect of a synthetic-grass sport surface on core body temperature, skin temperature, heart rate, thermal sensation, thermal comfort, and rating of perceived exertion (RPE) during intermittent exercise in hot conditions. Methods: Using a randomized crossover design, 13 trained/developmental team-sport athletes completed two 50-minute standardized intermittent running protocols on a synthetic and a natural-grass surface, on separate days (control-condition air temperature 32.6 °C [1.3 °C], relative humidity 43.2% [5.3%]). Results: Final skin temperature was significantly higher on synthetic compared with natural grass at the calf (40.1 °C [2.5 °C] vs 33.4 °C [0.6 °C]; P <.001), shoulder (36.6 °C [1.7 °C] vs 33.7 °C [0.7 °C]; P <.001), and chest (33.2 °C [1.1 °C] vs 31.8 °C [1.2 °C]; P =.02). Thermal sensation (median: 2.3; interquartile range [0.5] vs 2.2 [0.5], P =.03) and sweat rate (1.5 [0.4] L·h−1 vs 1.2 [0.3] L·h−1; P =.02) were also significantly higher on synthetic grass. While final core body temperature was significantly higher on the natural than synthetic grass (38.4 °C [0.3 °C] vs 38.2 °C [0.4 °C]), there were no significant differences in delta core temperature, as well as heart rate, thermal comfort, or RPE. Conclusions: Higher skin temperatures, thermal sensation, and sweat rates suggest that exercising on synthetic grass in hot conditions may increase some markers of heat strain during exercise. However, delta core body temperature, heart rate, thermal comfort, and RPE remained unaffected. [ABSTRACT FROM AUTHOR]

Compression therapy is a widely used treatment for various disorders including venous leg ulcers. Traditional methods such as inelastic bandages and elastic stockings, have limitations in maintaining optimal pressure over time. Dynamic therapy devices offer intermittent pressure cycles but are often bulky or rigid. Here liquid crystal elastomer (LCE) is proposed for both static and dynamic compression therapy. Due to the soft elasticity of polydomain LCE, LCE-based static stocking can maintain consistent pressure over a wide range of leg diameters, permitting the tolerance of stocking application inconsistencies, various limb sizes, and interfacial pressure drop due to leg deswelling. The LCE-based dynamic stocking consists of monodomain LCEs with reversible thermal actuation, heating elements, and electronics. The dynamic stocking generates intermittent pressure from 20 to 60 mmHg with a slight temperature increase above 33 °C and offers pressure profile programmability. Furthermore, an untethered LCE-based dynamic compression device on a human leg is demonstrated. Both LCE-based static and dynamic stockings show minimal stress relaxation and reusability over 1000 cycles, ensuring long-term use in compression therapy applications.

Ethylene-octene copolymer (EOC, three EOCs with different octene content used in this study) and propene-ethylene copolymer (EPC, three EPCs with different ethylene content used in this study) can have effects on the crystallization dynamics, crystal structure, and foaming properties of ethylene-vinyl acetate copolymer (EVA). For unfoamed EVA/EOC and unfoamed EVA/EPC blends, both EVA/EOC and EVA/EPC blends show phase separation structure. The foam cells in EVA/EOC blends have better uniformity compared to those in EVA/EPC blends, which result from the better compatibility of EVA and EOC than EVA and EPC obtained from the morphology- analysis. For the blends with different crystallization ability of EOC or EPC, the blends with lower crystallinity has more uniform cell distribution than blends with higher crystallinity, due to the crystallization zone cause heterogeneous cross-linking and foaming of the blend. Both EOC and EPC can impart higher elasticity to EVA foamed materials. EOC was found to be more suitable for blending with EVA for foamed materials, offering the potential to obtain EVA/EOC foamed materials with excellent performance. Highlights * Ethylene-octene copolymer with higher octene content has better effect on foaming property of ethylene-vinyl acetate copolymer than ethylenepropylene copolymer. * Ethylene-propylene copolymer can decrease the foaming temperature of ethylene-vinyl acetate copolymer. * A mechanism of foaming for ethylene-vinyl acetate copolymer/ semi-crystallized polymer blends is proposed. * Achieved in-depth understanding of structure-property relationship about ethylene-vinyl Acetate copolymer/polyolefin elastomer foamed material. KEYWORDS cthylene-octene copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, foaming properties, microstructure, 1 | INTRODUCTION Ethylene-vinyl acetate copolymer (EVA) is a copolymer with long branched chains formed through the free radical polymerization of ethylene and vinyl acetate, (1,2) which is widely used. [...]

The development of sustainable polymer materials is no longer just an option but a necessity. Elastomers are indispensable members of the polymer family due to their high tensile strength, durability, energy absorption capabilities, and excellent resistance to fatigue and environmental degradation. Elastomers have found a unique role in diverse industries, like transportation, automotive, aerospace, construction, and sports. However, elastomers are typically synthetic chemically crosslinked networks that are difficult to break down and recycle. Because of environmental impacts of synthetic elastomers, developing fully green or sustainable elastomers through green chemistry seems indispensable. This review aims to summarize and analyze existing reports on green elastomers, focusing on sustainable components, green chemistry, their performance, and sustainable manufacturing compared to conventionally used solutions. Due to the complexity of elastomer formulation—comprising numerous ingredients like base rubber or gum, curing agents, accelerators, activators, plasticizers, and other additives—creating fully sustainable elastomers, their blends, and composites with desirable properties remains a significant challenge. While no one has yet achieved this goal, a systematic and critical analysis of green chemistry principles in developing sustainable elastomers, with emphasis on green components, sustainable manufacturing and materials circularity considerations may be a feat of expediting decision-making processes toward a greener future ahead for the elastomer industry, and drive the development of fully green and sustainable elastomers. [ABSTRACT FROM AUTHOR]

A new organosilicon‐based polyurea/DOCIT composite coating with excellent mechanical, self‐healing characteristics has been successfully prepared in this paper. The optimal ratio of the two isocyanates has been explored to acquire the highest mechanical strength with 8.56 MPa and best tensile properties with 763%. The breaking strength and elongation remain 3.50 MPa and 915% with 1% antimicrobial agent DOCIT. The self‐healing characteristic comes from dense hydrogen and dynamic disulfide bonds between molecule chains. The composite coating exhibited ideal bacterial resistances for 98.02% and 96.75% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. The adhesion of chlorella was significantly reduced by approximately 86.48%. This work provides a promising avenue for the development of high‐performance silicone polyurea coatings for marine anti‐biofouling. [ABSTRACT FROM AUTHOR]

The limited strength and stability of conductive hydrogels greatly impede their practical applications in wearable devices. Therefore, a conductive double‐network hydrogel with high strength, high toughness, and high stability was prepared by one‐pot method in this paper. The rigid and flexible skeletons as well as the three‐dimensional dense honeycomb lattice network structure endow the hydrogel with good strength. The reversible cross‐linking synergistic effect between the rigid bacterial cellulose chains scaffolding uniformly dispersed Ti3C2 MXene nanosheets and the flexible acrylic acid chains doped with propylene glycol presents the hydrogel with excellent stability and elongation at break (862%). Consequently, a strain sensor based on the prepared hydrogel exhibits high sensitivity (GF = 1.28), rapid response (150 ms), and superior stability (over 2000 cycles) within a very wide strain range (5%–620%). Various strain signals generated by human activities are successfully detected by the presented strain sensor, which promises its broad applications in health monitoring. [ABSTRACT FROM AUTHOR]

In the contemporary modern mining sector, rubber conveyor belts are extensively and frequently utilized. Exceptional tear resistance and high elongation of the top cover rubber of the belt are imperative. In this investigation, a portion of natural rubber (NR) underwent partial vulcanization in advance. Subsequently, this pre‐vulcanized NR (PNR) was mixed with the NR matrix via mechanical blending. Due to the increased viscosity resulting from pre‐vulcanization, the PNR may disperse in the NR matrix, maintaining a specific microstructure without complete dissolution. During subsequent vulcanization, the PNR could co‐vulcanize with the NR matrix, forming a well‐bonded interface and ultimately yielding self‐reinforced NR (SNR) composites. The influences of the mass ratio of PNR to the NR matrix, sulfur content in PNR and pre‐vulcanization time on the mechanical properties of the SNR composites were thoroughly investigated. The results indicated that adding PNR effectively improved the tear strength of NR. When the PNR replaced 20 wt% of NR, sulfur content in PNR was 2.4 phr and pre‐vulcanization time was 2 min, the tear strength, stress at 300% elongation and wear resistance of SNR composites increased by 34.1%, 16.6%, and 10.2% compared to NR control sample, while elongation at break remained at 898%. These findings suggest that it is possible to enhance the tear strength of rubber without compromising elongation at break. [ABSTRACT FROM AUTHOR]

The series elastic actuator (SEA) with fixed stiffness and pre-compression volume elastomer poses challenges in adapting to various working requirements. To tackle this issue, this research proposes a temperature-controlled shape memory alloy (SMA) actuator integrated with a variable stiffness SEA. This innovative design enables the SMA to pre-adjust its length based on external loads and changing the stiffness of the SEA elastomer, by compensating for the SMA actuator displacements to adapt to different external loads, and reduce the unfavorable effect of the elastomer on the SEA output. First, the SEA joint structure was designed, then the mathematical model of the SMA actuator and the SEA dynamics model were established. Finally, the effect of the SMA actuator output displacement on the response of the joint was investigated through MATLAB/Simulink and Adams simulation using the PID control method. The results show that the SEA elastic equivalent body stiffness can be adjusted from spring stiffness to rigidity, which in turn enhances the output performance of the system, reduces the influence of the elastic element on the system output, and improves the adaptability of the joint in different environments. [ABSTRACT FROM AUTHOR]

Graphene nanoplatelets (GNPs) have emerged as promising additives for improving the properties of elastomeric compounds. This study investigates the influence of GNPs on styrene-butadiene rubber (SBR) formulations through a thorough assessment of rheological, mechanical, and thermal characteristics. Various mixing processes, including closed and open mixers, were employed to disperse GNPs effectively. Results demonstrate that the incorporation of GNPs accelerates vulcanization, increases crosslink density, enhances thermal conductivity, and improves mechanical strength in SBR compounds. Notably, open mixer processing yields superior dispersion and thermal conductivity compared to closed mixers. Additionally, GNPs mitigate the reduction in tensile strength observed during prolonged thermal aging. These findings highlight the multifunctional role of GNPs in elastomeric compounds and underscore the importance of dispersion techniques for optimizing their performance. Overall, this research contributes to advancing the understanding of GNPs as versatile additives for enhancing elastomeric materials, with potential applications across diverse industrial sectors. [ABSTRACT FROM AUTHOR]

In the present study, 20 wt% ENGAGE (a polyolefin elastomer) is melt blended with 80 wt% linear low-density polyethylene (LLDPE) followed by composite preparation with pistachio shell powder (PSP) in various compositions (40 wt% to 70 wt%). The effect of variation of PSP content on mechanical properties is studied. The processability of composites is improved because of the unique processability of ENGAGE. Consequently, filler-containing capability of the LLDPE/ENGAGE (LE82) blend is also enhanced considerably due to extra space generated by amorphous ENGAGE. Again, blending of 20 wt% ENGAGE with 80 wt% LLDPE is helpful for maintaining mechanical properties of LLDPE/ENGAGE/PSP composite in useful range. The rheological study confirms that complex viscosity (η), storage modulus (G') and loss modulus (G") remain almost unchanged with the incorporation of a high quantity of PSP into the LE82 blend system for all the composites in the entire frequency range. From the rheological study, it is seen that the thermoplastic nature of the composites is maintained. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) show the structural integrity of LE82 blend-based composites revealing the thermal stability of the organic filler and consequently the composites. SEM also shows uniform dispersion of PSP into the LLDPE/ENGAGE blend matrix. Such biocomposite with 70 wt% biodegradable component and reliable mechanical properties is attractive for wide spread applications. [ABSTRACT FROM AUTHOR]

Surface tension at cavity walls can play havoc with the mechanical properties of perforated soft solids when the cavities are filled with a fluid. This study is an investigation of the macroscopic elastic properties of elastomers embedding spherical cavities filled with a pressurized liquid in the presence of surface tension, starting with the linearization of the fully nonlinear model and ending with the enhancement properties of the linearized model when many such liquid filled cavities are present. [ABSTRACT FROM AUTHOR]

Elastomeric materials are commonly used as the padding of anti-vibration gloves for damping purposes. This study investigates the use of a breathable 3D knitted padding for vibration isolation in anti-vibration gloves. Sixteen (16) knitted fabric samples with different spacer structures, silicone inlay patterns, and inlay materials are produced to evaluate their effect on vibration transmissibility for a frequency range of 0-1000 Hz according to ISO13753:2008. The samples with the spacer structure that shows the best vibration isolation performance are made into the paddings for an anti-vibration glove which is then compared with four commercially available anti-vibration gloves in terms of vibration transmissibility based on ISO10819:2013. The results show that a thicker spacer structure with a larger number of needles in between the tuck stitches and inlaid with silicone hollow tubes can better isolate vibration. The vibration isolation performance of the 3D knitted fabric padded glove outperforms two commercially available gloves, though it falls short of the certified options. The findings show the possibility of using 3D knitted fabric as padding for anti-vibration gloves. However, further improvements to the glove and fabric design are needed to enhance the function and effectiveness of the glove. The development of lightweight breathable knitted padding can promote the wearing comfort of anti-vibration gloves which benefits the workers using vibrating hand tools and advances the development of personal protection equipment. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms underlying living anionic polymerization is essential for advancing efficient and sustainable elastomer production technologies. This study investigates the introduction of a functional styrene derivative at the initiation of a styrene‐butadiene polymer chain with high efficiency. Butyllithium is the most widely used initiator in anionic polymerization due to its high reactivity, availability, and ability to provide precise control over polymer molecular weight and structure. Modified initiators, formed from N‐(dimethyl(vinylbenzyl)silyl)‐N,N‐bis(trimethylsilyl)amine and isomers of butyllithium (n‐, sec‐, and tert‐), increase initiation efficiency and reduce oligomer formation. The developed procedure demonstrates the effective use of a functional styrene derivative as an alpha chain‐end modifier. The formation of a unimeric structure improves from 15.6% to 88.3%, significantly increasing the yield of alpha functionalization. Direct transfer of the functional styrene derivative to the alpha position expands the potential for functionalization in anionic polymerization. The activity of the preinitiators is evaluated in styrene‐butadiene anionic copolymerization. The functional initiators are terminated and characterized by high‐performance liquid chromatography coupled with gel permeation chromatography to assess the degree of polymerization. This method enables quantitative analysis of oligomer formation. The synthesized copolymers are further characterized by their molar masses, microstructure, Mooney viscosity, and glass transition temperature. [ABSTRACT FROM AUTHOR]

Electronic skins endow robots with sensory functions but often lack the multifunctionality of natural skin, such as switchable adhesion. Current smart adhesives based on elastomers have limited adhesion tunability, which hinders their effective use for both carrying heavy loads and performing dexterous manipulations. Here, we report a versatile, one-size-fits-all robotic adhesive skin using shape memory polymers with tunable rubber-to-glass phase transitions. The adhesion strength of our adhesive skin can be changed from minimal (~1 kilopascal) for sensing and handling ultralightweight objects to ultrastrong (>1 megapascal) for picking up and lifting heavy objects. Our versatile adhesive skin is expected to greatly enhance the ability of intelligent robots to interact with their environment. [ABSTRACT FROM AUTHOR]

The stability to against hydrolysis while maintaining excellent elasticity is one of the most challenging problems in the development of biodegradable and environmental-friendly polyester elastomer. While monomers of longer chain can provide higher stability, the high crystallinity and rigidity impair their application in fabricating elastomer. This work reported a star-crosslinked poly(butanediol-hexanediol-isosorbitol-itaconate-sebacate) elastomer synthesized by esterification and thermal curing. With the crystallization inhibition effect of isosorbide as a large and rigid monomer, and the flexibility of 1,6-hexanediol, the rigid (butanediol-itaconate-sebacate) copolyester system is successfully transformed from plastic to be elastomer with lower Tm and Tg, much higher elongation at break, and smaller tensile modulus, and the biodegradability is also improved. The strategy is demonstrated to be efficient and may serve as a potential technique in the future development of biodegradable elastomers. [ABSTRACT FROM AUTHOR]

In this research, the adhesive contact between a hard steel and a soft elastomer cylinder was experimentally studied. In the experiment, the hard cylinder was indented into the soft one, after which the two cylinders were separated. The contact area between the cylinders was elliptical in shape, and the eccentricity of this increased as the angle between the axes of the contacting cylinders decreased. Additionally, the adhesive pull-off force and the contact area increased with a decrease in the angle between the cylinders. The use of a transparent elastomer allowed for observation of the shape of the contact in real time, which facilitated the creation of videos demonstrating the complete process of contact failure and the evolution of the ellipse shape, depending on the distance between the cylinders and normal force. These findings contribute to a better understanding of adhesive interactions in elliptical contacts between cylinders and can be applied to fields such as soft robotics, material design, and bioengineering, where precise control over adhesion and contact mechanics is crucial. [ABSTRACT FROM AUTHOR]

Utilizing lithium metal as an anode in batteries has been expected to replace conventional lithium-ion batteries. However, the mechanical properties and electrochemical performance of current separators do not meet the requirements for practical applications of lithium metal batteries (LMBs). Here, we report an elastomer separator with an interconnected structure of plastic-crystal-embedded and garnet-conductor-regulated thermoplastic polystyrene-b-poly(ethylene-r-butylene)-b-polystyrene elastomer integrated with the polyethylene matrix. The 14-micron-thick elastomer separators show a combination of excellent elongation of ∼115.2% and sufficiently high tensile strength of ∼56 MPa. The elastomer separators accommodate volume changes and block dendrites for high-current-density cycling of LMBs. As a demonstration, the elastomer separators enable stable operation of LMBs under stringent conditions, a practical high loading of 18 mg cm−2 LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode at an extremely high charging/discharging current density of 1.8 mA cm−2, delivering a high reversible capacity of 164 mAh g−1 and capacity retention of 88% after 140 cycles. [ABSTRACT FROM AUTHOR]

Fiber‐metal laminates (FMLs) are generally regarded as excellent lightweight materials for advanced structure design. To enhance the mechanical properties, the common FMLs can be optimized using carbon fibers. However, the combination of carbon fibers with aluminum induces interfacial challenges. Preventing galvanic corrosion with elastomeric interlayers is an effective solution. The lay‐up configuration greatly effects the impact damage resistance of hybrid CFRP‐elastomer‐metal laminates (HyCEMLs). In this work, micro‐CT scans and optical micrographic inspections on HyCEMLs are conducted after impact tests to ascertain the microstructural origins behind the mechanical performance changes. In addition, finite element models of different HyCEML configurations are built to complement the limited experimental data. The damage mechanisms of HyCEML with different configurations under various impact conditions are further compared. The numerical results suggest that impact energy is a more informative measure in terms of damage mode and size than impact velocity and momentum. Results also indicate that when the thickness for each sub‐laminate of HyCEML is maintained the same, hybrid laminates with aluminum stacked outside is beneficial for delaying the occurrence of matrix cracking and delaminations, and enhances HyCEML's resistance to global deformation. These findings will contribute to engineering hybrid laminates with desired impact performance for lightweight load‐bearing structures. Highlights: The hybrid laminate with elastomeric interlayers is a forward‐looking solution in impact applications.Impact energy is a more informative measure in terms of assessing the damage mode and extent in HyCEMLs.The influence of stacking sequence on damage mechanisms of HyCEMLs is evaluated.Microstructural origins behind variations of hybrid laminates in the impact resistance are revealed. [ABSTRACT FROM AUTHOR]

The effect of single‐walled carbon nanotubes (SWCNTs) on the crosslinking network structure of Ethylene Propylene Diene Monomers (EPDM)—Polyamide elastomers (PAE) is investigated in detail using Hansen Solubility Parameter (HSP) theory. Rheological method and scanning electron microscopy (SEM) are used to investigate the effect of SWCNTs on the molecular chain movement and their interaction with the filler network of EPDM‐PAE. The DIN abrasion test is conducted to obtain the effect of SWCNTs on the wear characteristics of EPDM‐PAE/SWCNTs composites. The linear synergistic relationship between crosslinking density and wear volume indicates that the change in wear properties is contributed by the micro‐network structure. The addition of SWCNTs increases the chemical crosslinking density and improves the wear properties of EPDM‐PAE. However, the decrease in the physical crosslinking density leads to an increase in the degree of internal friction within the network structure, resulting in a decrease in the wear performance. Changes in wear resistance can be related to the micro‐network structure, which provides a novel approach to studying the wear characteristics of high‐performance elastomers. It is also an innovative work based on the network structure to guide the preparation of new wear‐resistant elastomeric materials. [ABSTRACT FROM AUTHOR]

Stable silicone encapsulants are essential for protecting high‐power light‐emitting diodes (LED) from dust and moisture and extending their service life. Herein, by incorporating thiol‐functionalized polyhedral oligomeric silsesquioxane (SH‐POSS) as a crosslinker into ultraviolet‐curable silicone elastomer (UVSE), a series of new UV‐cured silicone encapsulants (SH‐POSS/UVSE) have been developed through thiol‐ene click chemistry. It was found that SH‐POSS effectively enhanced the mechanical properties of SH‐POSS/UVSE. When 30 mol% SH‐POSS was added, the tensile strength and elongation at break reached 1.01 MPa and 422%, respectively, 2.1 and 1.6 times higher than pure UVSE. This could be ascribed to the more concentrated crosslinking network and the improved interfacial interactions between SH‐POSS and UVSE than physical blending. Moreover, the steric effect of branched and rigid SH‐POSS restricted the movement of UVSE molecular chains. Incorporating SH‐POSS also suppressed UVSE degradation and improved its thermal stability. Additionally, when the LED sample encapsulated by SH‐POSS/UVSE‐30 was immersed in boiling red ink for 2 h, no crack or stain was observed, indicating that SH‐POSS/UVSE‐30 possessed good adhesion to the LED lead frame. This work provides a new approach to fabricating high‐strength and stable silicone composites, which are promising candidates as LED encapsulants. [ABSTRACT FROM AUTHOR]

Stretchable elastic materials with high strength, toughness, and good ionic conductivity are highly desirable for wearable devices and stretchable batteries. Unfortunately, limited success has been reported to attain all of these properties simultaneously. Here, we report a family of ionically conductive elastomers (ICEs) without compromise between mechanical properties (high stiffness, reversible elasticity, fracture resistance) and ionic conductivity, by introducing a multiple network elastomer (MNE) architecture into a low T g polymer. The ICEs with the MNE architecture exhibit a room temperature ionic conductivity of the order of 10 − 6 S. cm − 1 and stress at break of ~8 MPa, whereas the simple networks without an MNE architecture show two orders magnitude lower ionic conductivity ( 10 − 8 S. cm − 1 ) and comparably low strength (<1.5 MPa) at 25 °C than their MNE architecture based counterparts. The MNE architecture with a low T g monomer combines the stiffness and fracture toughness given by sacrificial bond breakage while improving ionic conductivity through increased segmental mobility. Stretchable elastic materials with high strength, toughness, and good ionic conductivity are desirable for flexible electronics but attaining all of these properties simultaneously remains challenging. Here, the authors report a family of ionically conductive elastomers without compromise between mechanical properties and ionic conductivity by introducing a multiple network elastomer architecture into a low Tg polymer. [ABSTRACT FROM AUTHOR]

Septoplasty is among the most frequently performed procedures in the field of otorhinolaryngology. Adhesion is known to be the most common complication occurring after septoplasty. Post-surgical insertion of silicone splints is a widely used measure for the prevention of postoperative complications. Recently, we encountered a case where the silicone splint was dislocated and further displaced to the level of the upper esophageal sphincter. Although it was safely removed using fiberoptic gastroendoscopy, delayed removal could have induced other serious sequelae. Since no similar cases have been previously reported, we believe that this may be a very rare complication induced by a loose absorbable suture. Therefore, we suggest that otorhinolaryngologists should pay attention to the fixation of a silicone splint with sutures under appropriate tension to prevent the dislocation of the silicone splint and its subsequent sequelae. [ABSTRACT FROM AUTHOR]

A finite element model of the local mechanical response of a filled polymer composite to uniaxial compression is presented. The interfacial layer between filler particles and polymer matrix is explicitly modeled as a third phase of the composite. Unit cells containing one or several anisometric filler particles surrounded by interface shells are considered. The dependence of the mechanical response of the cells to external deformation on the interface thickness and stiffness is studied. The use of the particle–matrix interface as a damping tool in mesoscopic polymer-composite problems with large deformations is discussed. The influence of the interface on the anisotropy of the composite response is considered. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA), a favored bioplastic, is often limited in the packaging industry due to its inherent hardness and brittleness. To achieve a flexible PLA composite film through the extrusion-blowing method, we introduced a glycidyl methacrylate-grafted polyolefin elastomer (gPOE) and a reactive compatibilizer, ethylene methyl acrylate-glycidyl methacrylate random terpolymer (AX8900), into PLA to fabricate ternary blend films. In this film, both the gPOE and AX8900 offered multiple reactive sites to interact with the COOH and OH groups of PLA, thus leading to a stronger interfacial adhesion. The SEM micrographs also revealed its rough fracture surface with rich fibers, indicating its excellent compatibility performance. Compared to the neat PLA film and the binary blend films, those were PLA blended with picked single elastomers, the ternary blend films exhibited significantly enhanced elongation at break and demonstrates exceptional performance in terms of barrier properties and opacity. This work presents a facile approach for the fabrication of flexible PLA films, which holds great potential for application in the food packaging. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) offer versatile applications including haptics, soft robotics and smart lenses. However, due to the lack of conductive electrodes with low modulus and high stretchability, their use is limited by nonsolid electrodes, hindering integration with other systems. In this study, transparent and patternable solid electrodes, achieving actuation performance comparable to a commonly used non‐solid counterpart (e.g., carbon grease), with a stretchable and patternable conducting polymer composed of PEDOT:PSS and PEG‐PPG‐PEG diacrylate (P123DA) are reported. Varying the ratio of P123DA to PEDOT:PSS enables optimization of electrical and mechanical properties to achieve compliant solid electrodes in static and dynamic actuation. The ratio of P123DA to PEDOT:PSS is found to impact PEDOT:PSS nanofiber formation and the associated electrical and mechanical properties. Moreover, the resulting P123DA/PEDOT:PSS‐based solid electrode shows excellent optical transmittance exceeding 95%. This work highlights the potential of tuning different solid electrode properties to realize transparent, patternable, and stretchable solid electrodes, enhancing their applicability in diverse fields. [ABSTRACT FROM AUTHOR]

Transferring knowledge learned from standard GelSight sensors to other visuotactile sensors is appealing for reducing data collection and annotation. However, such cross-sensor transfer is challenging due to the differences between sensors in internal light sources, imaging effects, and elastomer properties. By understanding the data collected from each type of visuotactile sensors as domains, we propose a few-sample-driven style-to-content unsupervised domain adaptation method to reduce cross-sensor domain gaps. We first propose a Global and Local Aggregation Bottleneck (GLAB) layer to compress features extracted by an encoder, enabling the extraction of features containing key information and facilitating unlabeled few-sample-driven learning. We introduce a Fourier-style transformation (FST) module and a prototype-constrained learning loss to promote global conditional domain-adversarial adaptation, bridging style-level gaps. We also propose a high-confidence guided teacher–student network, utilizing a self-distillation mechanism to further reduce content-level gaps between the two domains. Experiments on three cross-sensor domain adaptation and real-world robotic cross-sensor shape recognition tasks demonstrate that our method outperforms state-of-the-art approaches, particularly achieving 89.8% accuracy on the DIGIT recognition dataset. [ABSTRACT FROM AUTHOR]

The azido propellant, with high energy and low signature, has been a hotpot in the field of propellants. However, the risk of low heat resistance and mechanical performance restricts their range of applications in high-energy formulations. In this study, four azido propellants based on 3,3-bis (azidomethyl) oxetane-tetrahydrofuran copolyether (BAMO-THF) have been prepared, their basic physical properties including energetic properties, internal micro-structure and true density were studied; their tensile properties, dynamic mechanical performances, were investigated, the structure-properties relationship was proposed. The results demonstrate that the obtained propellant shows an elastomeric composite material behavior, with an obvious relaxation in the initial stage and susceptibility to loading condition. The formula structure not only causes obvious difference in the second stage of relaxation, but also strongly affects the initial stage, which is quite different from the influence of testing condition. Besides, the low temperature toughness of the azido propellant is improved by using diol partly replaces diamine as a chain extender, but their stress modulus drop down obviously, leading to the notable stress relaxation behavior at high temperatures. It was found that the improvement of the ordering degree of microstructure or network integrity could restrict the stress relaxation, which was an effective approach to improve the heat resistance and mechanical performance of azido propellant at high temperatures. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Azo-containing liquid crystal elastomers are photomechanical materials that can be actuated via illumination. The photomechanical response is a result of the photoisomerization of the azo moiety, which produces bulk stresses in the material. These stresses arise via two distinct and competing mechanisms: order parameter change induced stress and direct contractile stress. We describe thermomechanical and photomechanical experiments aimed at assessing the relative contributions of these. We show that the details of the attachment of azo dyes to the network can greatly influence the photoresponse. We discuss our results and summarize our findings. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) are difficult to apply to flexible grippers due to their small deformation range and low output force. Hence, a DEA with a large bending deformation range and output force was designed, and a corresponding flexible gripper was developed to realize the function of grasping objects of different shapes. The relationship between the pre-stretch ratio and DEA deformation degree was tested by experiments. Based on the performance test results of the dielectric elastomer (DE), the bending deformation process of DEAs with different shapes was simulated by Finite Element Method (FEM) simulation. DEAs with different shapes were prepared through laser cutting and the relationship between the voltage and the bending angle, and the output force of the DEAs was measured. The result shows that under uniaxial stretching, the deformation of the DEA in the stretching direction gradually increases and decreases in the unstretched direction with the increase in the pre-stretch ratio. Under biaxial stretching, DEA deformation increases with the increase in the pre-stretch ratio. The shape of the DEA has a certain influence on the bending deformation range under the same conditions, and the elliptical DEA has a larger bending deformation range and higher output force compared with the rectangular DEA and the trapezium DEA. The elliptical DEA can produce a bending deformation of 40° and an output force of 37.2 mN at a voltage of 24 kV. The three-finger flexible gripper composed of an elliptical DEA can realize the grasping of a paper cup. [ABSTRACT FROM AUTHOR]

Many modern anti-icing and anti-fouling coatings rely on soft, low surface energy elastomeric materials such as polydimethylsiloxane for their functionality. While the low surface energy is desirable for reducing adhesion, very little work considers the larger contribution to adhesive failure caused by the viscoelastic nature of elastomers. Here we examine several different siloxane elastomers using a JKR adhesion test, which was operated over a range of different speeds and temperatures. Additionally, we characterize the dynamic mechanical modulus over a large range of frequencies for each material. We note that surface energies of the materials are all similar, but variation in adhesion strength is clear in the data. The variation at low speeds is related to elastomer architecture but the speed dependence itself is independent of architecture. Qualitative correlations are noted between the JKR adhesion measurements and the dynamic moduli. Finally, an attempt is made to directly compare moduli and adhesion through the recent Persson–Brener model. Approximations of the model are shown to be inaccurate. The full model is found to be accurate at low speeds, although it fails to precisely capture higher speed behaviour. [ABSTRACT FROM AUTHOR]

Biological springs can be used in nature for energy conservation and ultra-fast motion. The loading and unloading rates of elastic materials can play an important role in determining how the properties of these springs affect movements. We investigate the mechanical energy efficiency of biological springs (American bullfrog plantaris tendons and guinea fowl lateral gastrocnemius tendons) and synthetic elastomers. We measure these materials under symmetric rates (equal loading and unloading durations) and asymmetric rates (unequal loading and unloading durations) using novel dynamic mechanical analysis measurements. We find that mechanical efficiency is highest at symmetric rates and significantly decreases with a larger degree of asymmetry. A generalized one-dimensional Maxwell model with no fitting parameters captures the experimental results based on the independently characterized linear viscoelastic properties of the materials. The model further shows that a broader viscoelastic relaxation spectrum enhances the effect of rate-asymmetry on efficiency. Overall, our study provides valuable insights into the interplay between material properties and unloading dynamics in both biological and synthetic elastic systems.

Cutting of soft materials is a complex problem, which is still not well understood at the fundamental level, especially for soft materials. The cutting process we consider is slicing, which starts with indentation, followed by sliding of a knife on the material to be cut. Here, we describe cutting experiments on PDMS elastomers with three different moduli. Our experiments reveal typical stages of this cutting process, starting with indentation and ending at steady state cutting. The process starts with a pre-cutting phase in which the blade does not slip grossly relative to the solid to be cut, and deformation is mostly elastic. Slip of the blade initiates suddenly and is often accompanied by initiation of cutting. Cutting is relatively smooth in the next stage, which requires a continuous increase in shear force. For soft PDMS, this smooth cutting stage is followed by one in which folds or creases form on the cutting surface. The corresponding shear force response is no longer smooth as "steady" sliding occurs in a stick–slip fashion with oscillatory forces. The average shear force reaches a plateau and no longer increases with shear displacement. Experimental observations of the various cutting stages are interpreted quantitatively. [ABSTRACT FROM AUTHOR]

Hyper-viscoelastic models have been used to characterize large strains coupled with viscosity. In this study, we aimed to model the urethral in-vivo biomechanics through a hyper-viscoelastic implementation. First, we used isotropic 2-parameter Demiray model for identification of urethral tube inflation after refining the values of quasistatic states. Attempting the approach by Holzapfel et. al., the average ratio of the elastic and dynamic modulus was computed to determine the stress contribution of the viscoelastic branches. The values of the parameters were determined after constraining a constant Energy dissipation (generalized maxwell) over range 1s to 100s. For the hyper-viscoelastic comparison implementation, it was observed that the goodness of fit criteria performs good for half of the samples (Adjusted R2>0.95). In some samples, the model is limited to fit ‘S’ shape curves but still performed well. The above identification technique and the hyper-viscoelastic in-silico approaches show that our approach fares sufficiently for the creep response characterization of the urethra.

A nonlinear creep model based on fractional calculus theory is proposed to better describe the creep characteristics of transversely isotropic rock. The model includes a Hooke elastomer, a fractional Abel dashpot, a Kelvin body, and a nonlinear viscoplastic body, which effectively capture the three stages of creep (including the primary, steady-state, and accelerating creep stages) while also reflect the influence of different bedding angles on creep behavior. The parameters of the model are identified by the Levenberg–Marquardt algorithm. Compared to previous models assuming constant Poisson's ratio for transversely isotropic rock, our nonlinear creep model demonstrates improved accuracy and rationality. [ABSTRACT FROM AUTHOR]

Stretchable displays, capable of reversible expansion, represent significant advancements in free‐form display technologies. However, the high Poisson's ratio (ν) of elastomer substrates leads to unintended deformation under tensile strain, resulting in image warping. To address this, a meta‐elastomer (ME) substrate with a bidirectional zero ν, incorporating a self‐deformable soft mechanical metamaterial (MM) frame, is introduced. The ν of the ME is precisely programmed by the interaction between the deformation of the MM frame, which exhibits a negative ν, and the elastomer matrix, which has a positive ν. The soft MM frame, stiffer than the elastomer matrix, undergoes both structural deformation and length alteration during substrate tensile strain. This synergistic effect enables achieving a nearly bidirectional zero ν, thus overcoming the limitations of conventional tessellated rigid MM composites. Furthermore, the ME substrate, which is chemically cross‐linked at the junction interface, demonstrates exceptional mechanical robustness, enduring over 180% stretching and more than 10 000 cycles. By counteracting the Poisson's effect, the ME substrate with an integrated pixel array ensures translational pixel movement along the tensile axis during bidirectional stretching, minimizing undesired pixel movement in other directions. The stretchable ME presents key advancements for implementing more stable and reliable stretchable display applications. [ABSTRACT FROM AUTHOR]

Intrinsically stretchable devices often suffer from non‐uniform strain distributions under direct‐stretching conditions due to their large‐scale, patterned designs, leading to inconsistent performance. To address these issues, mechanochromic materials—substances that change color in response to strain—for precise and intuitive strain monitoring are employed. Leveraging this data, strategic design modifications, including extrinsic techniques such as rigid‐island with soft‐substrate and kirigami cuts are implemented, to mitigate strain non‐uniformity. Thus, highly desired uniform and homogenous strain control in a multi‐pixel stretchable system is achieved. By integrating these strain‐stopping with uniform strain control methods into arrays of rigid and soft chiral liquid crystal elastomers (CLCEs), effective color separation is demonstrated for encrypted information with enhanced strain uniformity and strain control. Additionally, the dynamic optical selectivity of circularly polarized light (CPL) of the CLCEs under specific conditions is explored, using uniaxial stretching to achieve both optical color changes and refined CPL separation. Consequently, leveraging the inherent optical properties of CLCEs, a uniform and highly functional multi‐pixel operating stretchable system is devised. The application of these extrinsic strain control strategies not only resolves issues of strain uniformity but also advances the field of stretchable smart materials, offering new possibilities for dynamic color‐ and polarization‐separating based on encrypted applications. [ABSTRACT FROM AUTHOR]

AbstractIn view of the increasing demand on harvesting electrical energy from ultra-low-frequency rotational machinery for energy-autonomous structural health monitoring, the dielectric elastomer (DE)-based rotational energy harvesting (EH) technology has become a promising solution. Therefore, this paper proposed a DE-based ultra-low-frequency rotational energy harvester consisting of a fiber-constrained DE generator with a two-dwell cylindrical cam mechanism. Electromechanical coupling model of the harvester is developed to investigate its performance under varied parameters for performance improvement. Results show EH performance of the harvester is improved by extending rising time or returning time of the cam, which provides guidance for designing high-performance harvesters. [ABSTRACT FROM AUTHOR]

Highlights As a type of field‐responsive smart material, electrorheological elastomers (EREs) have an adjustable modulus that is significantly affected by the orientation of the pre‐structures formed by dispersed particles. However, the imperfect orientation of the particles in the matrix under an external electric field limits the electrorheological (ER) performance of EREs. To solve this problem, rod‐shaped Fe3O4@TiO2 magnetic/electric dual‐responsive particles were fabricated and used to prepare novel EREs that were cured under a magnetic field, and EREs cured under an electric field served as a control group. Compared with the control group, more robust and denser particle chain structures were observed in the EREs cured under a magnetic field, and the initial modulus and relative electrorheological effect (ER) were superior to those of the control group. This method can be used to prepare high‐performance EREs with strong zero‐field mechanical properties and a wide modulus adjustment range suitable for engineering applications. The magnetic/electric dual‐responsive rod‐shaped Fe3O4@TiO2 particles were prepared. EREs filled with Fe3O4@TiO2 particles were prepared under magnetic or electric field. More robust and denser particle chains were formed in the EREs cured under a magnetic field. The EREs solidified under a magnetic field have higher relative ER effects. [ABSTRACT FROM AUTHOR]

Smart dry adhesives, a rapidly growing class of intelligent materials and structures, are engineered to provide strong, robust adhesion when needed while also allowing for controlled, easy detachment in response to specific stimuli. Traditional smart adhesives, often exemplified by fibrillar structures made of elastomers, face a number of challenges. These include limitations on maximum adhesion strength imposed by microstructural dimensions, restricted adaptability to surfaces with varying degrees of roughness, and an inherent trade-off between adhesion strength and switchability. This review explores how shape memory polymers (SMPs) can address these challenges and, through their rubber-to-glass (R2G) transition capability, provide a powerful foundation for the next generation of smart dry adhesives. Specifically, we summarize and elucidate the mechanisms by which SMPs enhance adhesion strength and switchability through material characteristics such as tunable stiffness, shape-locking, and shape-memory effects. Additionally, we discuss a wide range of innovative designs and applications of SMP adhesives, offering insights into the ongoing challenges and emerging opportunities in this rapidly evolving field. [ABSTRACT FROM AUTHOR]

Mechanical metamaterials have considerable application potential, but are often limited to single applications owing to material and manufacturing constraints. To achieve a “single structure, multiple applications” goal, this study presents a multifunctional metamaterial structure. The metamaterial cells gain significant deformation and recovery abilities by incorporating the concept of a tensegrity structure to balance flexibility and rigidity and using a rigid‐flexible fabrication process. Inspired by cat‐tongue barbs and Hooke's law, an innovative pre‐stress programming structure is designed for integrated fabrication, enabling multilevel pre‐stress control for each cell. This programmable stress allows the twin‐cell array to transition in situ from monostable to bistable states and provides multilevel critical‐force functions for bistable states. After assembling a nine‐cell array, the structure offers a wide range of adjustable stiffness levels, enabling soft‐rigid transitions and varied force‐displacement responses without the need for additional tools. It also allows controlled collapse ratios and deformation through stiffness control. Additionally, the nine‐cell array features isotropy with a Poisson ratio of v = −1 and clear indentation resistance. This approach is promising for applications such as adjustable energy dissipators, automotive equipment, and passive safety.Metamaterial cells produced via integrated fabrication gain an adjustable pre‐stress by incorporating the tensegrity concept. Using barb‐shaped locking structures to adjust the elastomer length (xn). Modulating the pre‐stress of adjacent cells achieves in situ multistability and critical‐force adjustability. The controllable stiffness of the nine‐cell array provides indentation resistance, a variable force‐displacement response, adjustable stiffness, and controllable deformation. [ABSTRACT FROM AUTHOR]