Compression Set Research Articles

Improving the mechanical properties and curing characteristics of styrene‐butadiene rubber/butadiene rubber composites by incorporating silicon carbide

AbstractThermal conductive filler, silicon carbide (SiC), has been investigated for its effects on the mechanical properties, microstructural properties, physical properties, and kinetic characteristics of styrene‐butadiene‐rubber/butadiene rubber (SBR/BR). SBR/BR‐SiC's tensile strength, strain at break, and toughness were improved by 5 phr SiC content within the composite. Specifically, there was a 44% increase in tensile strength, a 51% increase in strain at break, and impressive 113% increase in toughness. Additionally, there was a notable reduction of approximately ~15% in the compression set. The calculated crosslink density using the Flory–Rehner equation proved that the SiC filler increased the covalent bonds between the polymer chains during the curing reaction. The rheometry results showed a reduction in the scorch and optimum curing times by ~10% via the incorporation of SiC. The addition of 5 phr SiC decreased the curing duration time by 47%. The scanning electron microscopy images taken from the samples at different magnifications showed that the particle agglomeration after SiC = 5 phr was the main factor in reducing the SiC performance in the composite.Highlights Tensile properties of SBR/BR were improved with high thermal conductive SiC. SiC accelerated the rate of vulcanization reaction of SBR/BR. The crosslink density was maximized with the addition of SiC to the compound. Better heat transfer by SiC led to a reduction in the energy consumption of curing. Thermal diffusivity was raised with the addition of SiC to the compound.

Devonian to Early Carboniferous Retreating—Advancing Subduction Switch in the Northwestern Patagonia Accretionary Orogen: U‐Pb and Lu‐Hf Isotopic Insights

AbstractIn this contribution, we present new early middle Devonian igneous and metaigneous units with a major juvenile magmatic source input in the North Patagonian Massif, which were discovered through U‐Pb and Lu‐Hf zircon analyses. Afterward, we assessed their tectonic implications for northwestern Patagonia and then for southern South America, combining our results with available database information consisting of igneous crystallization ages and isotopic data of the Devonian to early Carboniferous magmatic units, tectonic‐metamorphic analyses, and thermochronologic record. This study allows for distinguishing retreating and advancing subduction switching in northwestern Patagonia (38°30′ to 44°S) and a contrasting coetaneous evolution for basement outcrops exposed further north (27°30′ and 37°30′S). The early middle Devonian (400–380 Ma) northwestern Patagonian magmatism is characterized by widespread magmatism and positive εHf–εNd linked to forearc and backarc magmatism that evolved within a retreating subduction stage. A tectonic switching toward advancing orogeny stage began in the late Devonian, evidenced by a lull in magmatic activity with a negative εHf–εNd trend, possibly contemporaneous with the first tectonic‐metamorphic event in western Patagonia. An early Carboniferous magmatic gap, followed by the subsequent development of the main foliation in the basement during the Carboniferous‐Permian period, denotes the acme of this contractional stage. In contrast, the Devonian period in the northern segment is characterized by mostly negative εHf–εNd values, reverse shear zone activity in the foreland, and an inboard magmatism migration, evidencing a compressive tectonic setting that changed to an extensional configuration in the early Carboniferous with widespread arc magmatism development.

Vibration and noise reduction for building floor structures based on new composite material vibration isolation pads

The frequent occurrence of geological disasters poses a significant threat to human life and the safety of property. To enhance the seismic performance and reduce noise in buildings, this study proposes the design of building floor structures with a new composite vibration isolation pad. Carbon nanocoils/styrene-butadiene composites are utilized to create vibration reduction devices. Experimental results demonstrate that the compression set rates of carbon nanocoil composite rubber are 4.83% and 2.07% at filling amounts of 1% and 3%, respectively. Additionally, the compression set rates of carbon nanotube composite rubber are 13.79% and 6.90%, respectively. Among these materials, styrene-butadiene exhibits the most significant performance improvement when combined with carbon nano coil. With an optimal layout of 25 devices, the floor dynamic amplification coefficient can be reduced by 8.4% and the building floor noise can be reduced by approximately 75%. This optimization significantly reduces the dynamic response and also provides a certain level of noise reduction effect.

Application of Carboxy Terminated Liquid Natural Rubber as a polymeric compatibilizer in commercial nano silica filled NR/NBR and PVC/NBR blends

Blends of polymers are mixtures of two or more polymers, having different properties and require compatibilization. The compatibilization must ensure the improvement in morphological homogeneity and performance of materials in terms of its physical and mechanical characteristics. Maleic anhydride can be able to link chemically with depolymerized natural rubber to generate the Carboxy Terminated liquid Natural Rubber (CTNR). The utilization of the CTNR as a prospective and affordable compatibilizer and the usage of the commercial nano silica (NS) as a green, reinforcing and beneficial filler which could boost the tensile characteristics, ageing and oil resistance of both the NR/NBR and PVC/ NBR blend vulcanizates are described in this work. The properties of commercial NS filled NR/NBR and PVC/ NBR blend vulcanizates were compared with those containing amorphous silica. The effect of altering the quantity of CTNR on the properties of commercial NS filled NR/NBR and PVC/ NBR blend vulcanizates were also studied. The introduction of CTNR as a compatibilizer could enhance the tensile properties, ageing and oil resistance and upgrade the compression set of NS filled NR/NBR blend vulcanizates. The NS filled PVC/ NBR blend vulcanizates exhibit an improvement in the tensile properties, hardness, ageing and oil resistance by the use of CTNR as the compatibilizer. The addition of CTNR increases the crosslink density of both NS filled NR/NBR and PVC/NBR blend vulcanizates. Fruitful blending of NR/NBR and PVC/NBR was accomplished by the use of commercial NS and the production of CTNR through sunlight irradiation of NR and maleic anhydride.

Preparation of EPDM/silicon nanofibers-graphene nanocomposites with enhanced interfacial structure: Highly reinforcing and stabilizing effect

Aiming at designing enhanced interfacial structure, TA@SiNF/PGNs hybrids with hydrogen bonding and π-π conjugation were constructed through wrapping of polyrhodanine on graphene nanosheets (GNs) and self-polymerization of tannic acid (TA) onto SiNF surface. EPDM/TA@SiNF/PGNs nanocomposites were further prepared and the enhanced interfacial interactions were achieved, which promoted good dispersion of the hybrid nanofillers. Compared with EPDM, addition of TA@SiNF/PGNs resulted in a significant increase in mechanical strength and fracture toughness, and the mechanical strength of EPDM/TA@SiNF/PGNs was much better than EPDM/TA@SiNF or EPDM/PGNs due to the increased crosslinking density, indicating remarkably reinforcing and toughening effect of TA@SiNF/PGNs. In addition, the lower compression set and higher contact stress relaxation coefficient were achieved, revealing an improvement of compressive resilience. Moreover, TA@SiNF/PGNs effectively slowed down the deterioration of mechanical properties after thermo-oxidative aging, and the higher retention of crosslinking density and prolonged oxidation induction time confirmed the excellent stabilization effect of TA@SiNF/PGNs.

Screening of sealing materials for PEM fuel cell applications based on weight factor method

AbstractThe inexpensive, endurable sealing members are among the key components determining the performance and durability of proton exchange membrane fuel cells (PEMFCs). However, there is a lack of effective in situ measurement to monitor the sealing performance change in the fuel cell operation environment. Therefore, the durability of a sealing material should be assessed previously to its application. The present work investigates four types of commercially available sealing silicone rubbers, and five groups of aging tests are carried out to compare their properties and durability in a simulated PEMFC environment, including compression set, stress relaxation, compression stress–strain, solution soaking, and low‐temperature characterization. Furthermore, to comprehensively evaluate the performance of these four types of silicone rubbers and screen out the most suitable one, a comprehensive evaluation table of sealing materials selection based on weight factor was established through an expert survey method, by which the experimental results of all the silicone rubbers can be weighted and scored. This method can be widely used in the fuel cell industry.

Structure–Property Correlation in Natural Rubber Nanocomposite Foams: A Comparison between Nanoclay and Cellulose Nanofiber Used as Nanofillers

Nanocomposite foams of natural rubber (NR) with 5 phr of two kinds of nanofillers, nanoclay (NC) and cellulose nanofiber (CNF), were produced using the latex mixing method and foaming with azodicarbonamide. The effect of the nanofiller on the structure and mechanical properties of NR foams was investigated through SEM, TEM, tensile tests, WAXD, and compression set measurements. Smaller cells with a narrower distribution were attained in the NC/NR foam when compared to the NR and CNF/NR foams, and the expansion ratio was larger due to the suppression of the shrinkage in the NC/NR foam. The foaming of the NR nanocomposites reduced the size of the filler aggregates and improved the dispersion and alignment of nanofillers in the cell walls. The addition of NC and CNF enhanced the tensile strength of the NR foam by 139% and 62%, respectively, without sacrificing the excellent strain of the NR, due to the acceleration of the strain-induced crystallization and small size of the filler aggregates. The compression set of the NR foam could also be reduced in the NC/NR foam compared with the NR and CNF/NR foams.

Efficient physics-based learned reconstruction methods for real-time 3D near-field MIMO radar imaging

Near-field multiple-input multiple-output (MIMO) radar imaging systems have recently gained significant attention. These systems generally reconstruct the three-dimensional (3D) complex-valued reflectivity distribution of the scene using sparse measurements. Consequently, imaging quality highly relies on the image reconstruction approach. Existing analytical reconstruction approaches suffer from either high computational cost or low image quality. In this paper, we develop novel non-iterative deep learning-based reconstruction methods for real-time near-field MIMO imaging. The goal is to achieve high image quality with low computational cost at compressive settings. The developed approaches have two stages. In the first approach, physics-based initial stage performs adjoint operation to back-project the measurements to the image-space, and deep neural network (DNN)-based second stage converts the 3D backprojected measurements to a magnitude-only reflectivity image. Since scene reflectivities often have random phase, DNN processes directly the magnitude of the adjoint result. As DNN, 3D U-Net is used to jointly exploit range and cross-range correlations. To comparatively evaluate the significance of exploiting physics in a learning-based approach, two additional approaches that replace the physics-based first stage with fully connected layers are also developed as purely learning-based methods. The performance is also analyzed by changing the DNN architecture for the second stage to include complex-valued processing (instead of magnitude-only processing), 2D convolution kernels (instead of 3D), and ResNet architecture (instead of U-Net). Moreover, we develop a synthesizer to generate large-scale dataset for training the neural networks with 3D extended targets. We illustrate the performance through experimental data and extensive simulations. The results show the effectiveness of the developed physics-based learned reconstruction approach compared to commonly used approaches in terms of both runtime and image quality at highly compressive settings. Our source codes and dataset are made available at https://github.com/METU-SPACE-Lab/Efficient-Learned-3D-Near-Field-MIMO-Imaging upon publication to advance research in this field.

Mechanical characteristics and regression models of rice husk silica reinforced natural rubber composites

Carbon black and silica fillers have been widely used as reinforcing fillers in tyres and engine mounts. However, both fillers are non-renewable and with REACH legislation in Europe, the USA and elsewhere, where some of these fillers are termed hazardous due to the presence of polyaromatic hydrocarbons (PAHs), there is a need to search for sustainable alternative fillers to wholly or partially replace carbon black as a filler. This research studied rice husks-derived silica (RHS) as a filler in natural rubber (NR). The characteristics of RHS at 50 phr to 90 phr filler loading levels were examined to determine its suitability as a substitute for unsustainable carbon black (N772) fillers used in the rubber industry. Bound rubber content, crosslink density, tensile strength, young modulus, tear strength, shore A hardness, compressive set, and elongation at break were measured. Regression models were generated and the correlation of determination (R2) values was obtained. The RHS composites resulted in maximum tensile strength of 13.20 MPa at 90 phr, tear strength of 119 MPa at 90 phr, shore A hardness of 69 at 90 phr, compressive set of 6.72% at 80 and 90 phr, elongation at break of 453.60% at 80 phr, bound rubber content of 92.14% at 50 phr and crosslink density of 3.87×10-2 mol/cm3 at 70 phr. The results obtained were within the range of those obtained for the carbon black filled composites across various loading levels. The R2 value of mechanical characteristics for the RHS and N772 samples respectively were 50.06% and 62.18% (bound rubber content), 97.62% and 99.85% (tensile strength), 98.44% and 63.97% (tear strength), 89.16 and 97.40% (Shore A hardness), 32.90% and 91.80% (compressive set), a d 50.91% and 46.91% (elongation at break). Rice husk-derived Silica filled natural rubber composites showed favourable mechanical properties and can substitute traditional fillers in tyres, rubber engine mounts, bushings, seals and doormats.

Preparation and properties of silane cross-linked polyethylene nanocomposite foams: The effect of silane and nanoclay type and content

In this study, silane grafted and moisture cross-linked low density polyethylene nanocomposite foams were prepared by melt mixing and batch foaming process and the effects of silane content, nanoclay content, foaming agent concentration and clay type (clay modified with vinyltriethoxysilane (VTES) and amino-propyltriethoxysilane on foaming efficiency and foam properties were investigated. The morphology and the efficiency of silane modification of modified clay were characterized by series of tests, including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The results of Fourier transform infrared and thermogravimetric analysis showed that the silane modifiers were bonded to the surface of nanoclay through both physical and chemical bonds. According to XRD, these modifiers caused characteristic peak of clay to shift to lower angles, and make an increase in basal spacing. Gel content, density, scanning electron microscopy, compression, creep and rheological tests were used to determine the effect of different parameters on properties of cross-linked polyethylene foams. Results indicated that silane content has the significant effect on stress-strain behavior in compression mode. Compression set and creep deformation were affected by cell size and gel content. Furthermore, the rheological properties including complex viscosity, storage and loss modulus of unformed samples increased with the addition of silane and nanoclay content.

Effect of zinc oxide/layered double hydroxide on the mechanics of silicone rubber at low temperature

Low-temperature conditions can degrade various properties of rubber, impacting the application of rubber products in such conditions. In this study, we incorporated zinc oxide (ZnO) and magnesium aluminum layered double hydroxide (LDH) into silicone rubber (SR) to produce x-ZnO/LDH/SR composites, where X represents the addition ratio of ZnO to LDH. The results indicated that, at −40 °C, the tensile strength and elongation at break for 1/2-ZnO/LDH/SR were 10.6 % and 5.0 % greater than the original silicone rubber, respectively. In addition, after aging at −40 °C for 3 days, the compression set of the composites decreased by 48.6 %. This improvement was attribute to ZnO and LDH forming a physical cross-linking network within the rubber. This not only enhanced the mechanical properties of silicone rubber at low temperatures but also offers a straightforward and viable approached to producing high-performance, low-temperature-resistant sealing products.

Enhancement mechanism of micro-iron ore tailings on mechanical properties and hydration characteristics of cement-steel slag system

The limited cementitious activity of steel slag (SS) powder restricts its large-scale utilization as a replacement material for Portland cement and even more so for inert iron ore tailings (IOT). The micro-IOT (MIOT) were utilized as additives to improve the compressive strength and hydration degree of a binary system containing SS and PC. Compressive strength, flowability, and setting time were measured. The mechanism of MIOT on the hydration properties and microstructure of the cement–SS binary system was investigated using XRD, TG, FTIR, SEM, and MIP. The results revealed that the 28-d compressive strength of composite mortar S20M10 (20% SS and 10% MIOT) with MIOT added to the cement–SS system was 50.32 MPa, which was 93.41% of that of the cement samples and 16.16% higher than the compressive strength of the cement-SS system. Wet grinding of IOT lowered the crystallinity and surface binding energy, increased the reactivity, and facilitated the participation of MIOT in the hydration reaction with the reactive silica-alumina phases in SS, producing more C–S–H. The formation of carbonate AFm phases in the composite system improved the strength. MIOT in suitable dosage can limit the maximum possible pore and porosity of the composite system, increasing the structure's complexity and making the hardened slurry denser. This study provides a solution for IOT activity activation and promotes high-value utilization of SS and IOT.

Evaluation of compressive strength and setting time of some types of calcium silicate based materials modified with chicken egg shell powder

Evaluation of compressive strength and setting time of some types of calcium silicate based materials modified with chicken egg shell powder

Preparation of Multifunctional Additive [MFA] from Castor Oil (CO) and Study of its Effects on the Physical Properties of Natural Rubber Vulcanizates

This experiment focuses on the synthesis of Multifunctional Additives (MFA) from Castor seed oil (CO) and pure Oleic acid (OA) respectively. These multifunctional additives (CO-MFA and OA-MFA) were investigated as potential substitutes for process oil, activator, co-activator, and accelerator in the formulation of a natural rubber vulcanizate. During processing, the castor seed oil was characterized for acid value (AV), free fatty acid (FFA) and saponification value (SV) and subsequently reacted with 1, 6-hexane diamine to obtain a mixture of salts termed castor oil-based multifunctional additives (CO-MFA), similarly, a pure oleic acid was also reacted with 1, 6-hexane diamine to obtain a pure salt termed oleic acid-based multifunctional additive (OA-MFA). These compounds were investigated as substitutes for process oil/stearic acid, process oil/stearic acid/zinc oxide, process oil/MBT, and process oil/stearic acid/zinc oxide/MBT in the formulation and compounding of natural rubber vulcanizate. The pre-mastication of the rubber and subsequent mixing with additives was carried out in a Banbury Internal Mixer at a rotor speed of 50 rpm for 7 mins while the vulcanization was achieved on a compression molding machine at a temperature of 140oC for 15 mins. The various vulcanizates samples were evaluated for tensile properties, compression set, abrasion resistance, and hardness. The use of castor seed oil-based multifunctional additives (CO-MFA) as a substitute for process oil/stearic acid/zinc oxide/MBT gave the highest value of tensile strength (12.24 MPa) as against the conventional rubber compound (4.21 MPa).

FEASIBILITY OF USING Zanthoxylum ekmanii (Urb.) Alain FOR PLYWOOD PANEL PRODUCTION

Feasibility of using Zanthoxylum ekmanii (Urb.) Alain for plywood panel production.The demand for wood-based products by society is growing because these products are less restrictive, highly resistant, and reliable in use. However, due to a lack of technological knowledge, the number of Amazonian species used within the timber industries is still limited. Therefore, knowing the potential use of these species is important to the forestry sector’s development. In this context, this study aimed to evaluate the physical and mechanical properties of plywood panels produced with veneer sheets of Zanthoxylum ekmanii (lemon) and its combination with Pinus sp., using the urea-formaldehyde (UF) and (PF) phenol-formaldehyde resins. Panels were produced with 15 mm, dimensions of 50 x 50 cm, and a grammage of 360 g/m2 in a single line. Physical and mechanical tests were performed by the specifications described in the Brazilian standards. The results were compared to the requirements of the ABIMCI technical catalog and the NBR ISO 12466-2 standard. The homogeneous and combined panels with Z. ekmanii evaluated in this study presented results of water absorption, thickness swelling, compression set recovery, glue line shear strength, and parallel and perpendicular static bending statistically equal to or superior to the reference species (Pinus sp.). Therefore, the panels produced with Z. ekmanii have good quality in bonding with UF and PF resins. This species can be used in the production of homogeneous plywood or combination with Pinus sp.

Cure characteristics, compression set, swelling behaviors, abrasion resistance and mechanical properties of nanoclay (Cloisite 15A, Cloisite 20A and Cloisite 30B) filler filled EPDM/NBR blend system

Cure characteristics, compression set, swelling behaviors, abrasion resistance and mechanical properties of nanoclay (Cloisite 15A, Cloisite 20A and Cloisite 30B) filler filled EPDM/NBR blend system

Upcycling Fly Ash, Red Clay Brick Waste, and Paper Sludge as Feedstock for Manufacturing a Lightweight Extruded Composite: Design and Characterization

In the context of the circular economy and the adoption of one of its business models, namely ”resource recovery”, this study presents an opportunity to valorize industrial and urban wastes using alkaline activation technology to produce hybrid binders. Several alkali-activated binders were produced using response surface methodology based on a mixture of 45/45/10 clay brick waste, fly ash, and Portland cement. The compressive strength and setting time of each were evaluated. The hybrid cementitious pastes achieved up to 45 MPa after 28 days of setting. Based on the experimental data, two binders were selected as the cementitious matrix for composites, with paper sludge as the lightweight aggregate. Incorporating up to 45% volume of paper sludge allowed extrusion of the materials. The addition of paper sludge reduced the compressive and flexural strength. These results were explained by the decrease in density and the increase in porosity. However, there was an improvement in the thermal properties of the composites; in particular, the thermal conductivity range between 0.35 and 0.49 W/mK. Finally, it was found that the composites with 25% volume of paper sludge had the best combination of properties, positioning them as potential construction materials.

Effect of Modified Nanographene Oxide Loading on the Swelling and Compression Set Behavior of EPDM/SBR Nano-composites

Effect of Modified Nanographene Oxide Loading on the Swelling and Compression Set Behavior of EPDM/SBR Nano-composites

In situ titanite ages and Mesozoic metamorphism of Paleoproterozoic mafic granulites from the Wuhe metamorphic complex, southeastern North China Craton

The Wuhe Complex in the southern section of the Jiao-Liao mobile belt (JLMB) consists of an Archean–Paleoproterozoic crystalline basement and is essential for understanding the intricate tectonic evolution history of the southeastern North China Craton (NCC). Owing to the lack of Mesozoic metamorphic ages reported from the southern section of the JLMB, it is unclear whether the Wuhe Complex experienced Mesozoic tectonothermal overprint events. Titanites are common uranium-bearing minerals for U–Pb dating and are prone to metamorphic, tectonothermal, or hydrothermal processes. Thus, titanites were used in this study to unravel late metamorphic overprint events. Mesozoic titanites from the mafic granulites of the Wuhe Complex are believed to be of metamorphic origin and have experienced amphibolite-facies metamorphism, with a temperature range T = 677–723 ℃ and a pressure of P = 3.8 kbar. Laser ablation-inductively coupled plasma-mass spectroscopy U–Pb dating and in situ U–Pb dating of titanites yielded ages of 163–112 Ma and 123 Ma, respectively. This implies that the Wuhe Complex may have experienced a Mesozoic metamorphic overprint event during the tectonic transition period (from a subduction-related compressive setting to a tectonic stretch setting). Given the large number of Mesozoic intrusive rocks distributed across the NCC, it is important to rule out the effect of late tectonothermal events when studying Neoarchean or Paleoproterozoic metamorphism in the NCC.

Analysis of the Performance of IoT Networks in Acoustic Environment by using LZW Data Compression Technique

The Internet of Things (IoT) has experienced phenomenal growth, opening up a wide range of applications in many settings. Due to the properties of sound propagation, IoT networks operating in acoustic environments in particular present special difficulties. Data compression techniques can be used to minimize overhead and maximize resource utilization in these networks to increase performance. The performance of IoT networks in acoustic environments is examined in this study, with a focus on routing overhead, throughput, and typical end-to-end delay. Lempel-Ziv-Welch (LZW) data compression is used to reduce data size and boost communication effectiveness. Three well-known protocols—MQTT, CoAP, and Machine-to-Machine (M2M)—are assessed in relation to acoustic Internet of Things networks. To mimic different acoustic conditions and collect performance metrics, a thorough experimental setup is used. Different network topologies, data speeds, and compression settings are used in the studies to determine how they affect the performance metrics. According to the analysis's findings, all three protocols' routing overhead is greatly decreased by the LZW data compression approach, which enhances network scalability and lowers energy usage. Additionally, the compressed data size has a positive impact on network throughput, allowing for effective data transmission in acoustic contexts with limited resources. Additionally, using LZW compression is seen to minimize the average end-to-end delay, improving real-time communication applications. This study advances knowledge of IoT networks operating in acoustic environments and the effects of data reduction methods on their functionality. The results offer useful information for network engineers and system designers to optimize the performance of IoT networks in similar situations. Additionally, a comparison of the MQTT, CoAP, and M2M protocols' suitability for acoustic IoT deployments is provided, assisting in the choice of protocol for particular application needs.