Reinforcement of rubber by nanofillers has been a topic of great interest in recent years. This work compares the reinforcing efficiency of nanofillers with different topologies such as spherical (carbon black and silica), fibrous (silicon carbide nanofibers and carbon nanotubes), and sheetlike (nanoclays, expanded graphite, and graphene) in two different diene rubbers (natural rubber [NR] and styrene–butadiene rubber [SBR]) at low loadings. Tensile strength improved by 88% in the case of NR and 57% in the case of SBR by the addition of just 3 phr of graphene nanoplatelets with high aspect ratio and surface area. An increase in the Mooney–Rivlin constant (C1) with filler loading variation was also observed for these filler systems in NR and SBR. The analysis of the composites using a tube model showed that the confinement of rubber chains due to the presence of fillers with a high aspect ratio gave rise to a lower tube diameter. The addition of nanofillers resulted in higher hysteresis losses, confirming their ability for higher energy dissipation. A higher Payne effect was observed in the composites due to the formation of a percolating filler network, which was accompanied by a weak strain overshoot in the loss modulus. Dynamical mechanical analysis of the composites showed a significant increase in the storage modulus of the composites at both low and room temperatures. The reduction observed in the tan δ was correlated with the crosslink density of the composites.
{"title":"MECHANICAL PROPERTIES OF NATURAL RUBBER AND STYRENE–BUTADIENE RUBBER NANOCOMPOSITES WITH NANOFILLERS HAVING DIFFERENT DIMENSIONS AND SHAPES AT LOW FILLER LOADING","authors":"K. Surya, A. Bhowmick","doi":"10.5254/rct.22.77933","DOIUrl":"https://doi.org/10.5254/rct.22.77933","url":null,"abstract":"\u0000 Reinforcement of rubber by nanofillers has been a topic of great interest in recent years. This work compares the reinforcing efficiency of nanofillers with different topologies such as spherical (carbon black and silica), fibrous (silicon carbide nanofibers and carbon nanotubes), and sheetlike (nanoclays, expanded graphite, and graphene) in two different diene rubbers (natural rubber [NR] and styrene–butadiene rubber [SBR]) at low loadings. Tensile strength improved by 88% in the case of NR and 57% in the case of SBR by the addition of just 3 phr of graphene nanoplatelets with high aspect ratio and surface area. An increase in the Mooney–Rivlin constant (C1) with filler loading variation was also observed for these filler systems in NR and SBR. The analysis of the composites using a tube model showed that the confinement of rubber chains due to the presence of fillers with a high aspect ratio gave rise to a lower tube diameter. The addition of nanofillers resulted in higher hysteresis losses, confirming their ability for higher energy dissipation. A higher Payne effect was observed in the composites due to the formation of a percolating filler network, which was accompanied by a weak strain overshoot in the loss modulus. Dynamical mechanical analysis of the composites showed a significant increase in the storage modulus of the composites at both low and room temperatures. The reduction observed in the tan δ was correlated with the crosslink density of the composites.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44036682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stretchable electronics are being used in applications such as wearable electronics, robotic skin, wearable health-monitoring devices, and smart textiles due to their excellent mechanical conformability through stretching, flexing, twisting, and folding. This work focuses on creating printable stretchable substrates based on butyl rubber (IIR), combined with a ferroelectric filler, barium strontium titanate (BST). BST has unique properties, including the ability to tune the dielectric properties by applying a bias to the substrate. A high loading of BST was incorporated to tailor the dielectric properties of the substrate. This work investigated the effect of three different cure systems on the properties, including interaction with a silver ink. For all cure systems, cure and scorch time decreased with increases in BST loading. A phenolic cure did not affect the ink conductivity, whereas the sulfur-cured systems resulted in nonconductive ink. For the phenolic-cured substrate, the tensile strength increased and the elongation decreased with increasing filler loading. The elastomer could be filled with up to 40 vol. % BST while still maintaining elongation greater than 200%.
{"title":"MANUFACTURING OF ELASTOMERIC SUBSTRATES FOR STRETCHABLE PRINTED ELECTRONICS","authors":"S. Deshmukh, Erin P. Keaney, Carol Barry, J. Mead","doi":"10.5254/rct.22.77936","DOIUrl":"https://doi.org/10.5254/rct.22.77936","url":null,"abstract":"\u0000 Stretchable electronics are being used in applications such as wearable electronics, robotic skin, wearable health-monitoring devices, and smart textiles due to their excellent mechanical conformability through stretching, flexing, twisting, and folding. This work focuses on creating printable stretchable substrates based on butyl rubber (IIR), combined with a ferroelectric filler, barium strontium titanate (BST). BST has unique properties, including the ability to tune the dielectric properties by applying a bias to the substrate. A high loading of BST was incorporated to tailor the dielectric properties of the substrate. This work investigated the effect of three different cure systems on the properties, including interaction with a silver ink. For all cure systems, cure and scorch time decreased with increases in BST loading. A phenolic cure did not affect the ink conductivity, whereas the sulfur-cured systems resulted in nonconductive ink. For the phenolic-cured substrate, the tensile strength increased and the elongation decreased with increasing filler loading. The elastomer could be filled with up to 40 vol. % BST while still maintaining elongation greater than 200%.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46774941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaolei Wang, H. Pan, Lan Cao, Chunfu Wang, Chengzhong Zong
Tea polyphenols and vitamin C are used as reducing agents that are introduced into nitrile–butadiene rubber (NBR) and NBR/graphene oxide (GO) latex systems, and the double bonds in the NBR and the GO sheet in NBR/GO are simultaneously hydrogenated and reduced through the synergistic hydrazine hydrate/hydrogen peroxide/copper sulfate catalytic system to prepare hydrogenated NBR (HNBR) and HNBR/reduced GO (RGO) nanocomposites. The degree of hydrogenation of the product is improved and the gel content of the product is reduced, which effectively solves the problems of the low degree of hydrogenation and high gel content in the diimide catalytic hydrogenation system. At the same time, the HNBR and HNBR/RGO nanocomposites, which are co-reduced by tea polyphenols and vitamin C, have good thermal stability and mechanical properties. Tea polyphenols are more likely to participate in the hydrogenation reaction. The degree of hydrogenation of the NBR double bonds is higher than the amount of reduction occurring within the GO sheet with the addition of tea polyphenols.
{"title":"INTRODUCING TEA POLYPHENOLS AND VITAMIN C TO IMPROVE THE IN SITU HYDROGENATION AND REDUCTION PROCESS OF NBR AND NBR/GO LATEX","authors":"Xiaolei Wang, H. Pan, Lan Cao, Chunfu Wang, Chengzhong Zong","doi":"10.5254/rct.22.77994","DOIUrl":"https://doi.org/10.5254/rct.22.77994","url":null,"abstract":"\u0000 Tea polyphenols and vitamin C are used as reducing agents that are introduced into nitrile–butadiene rubber (NBR) and NBR/graphene oxide (GO) latex systems, and the double bonds in the NBR and the GO sheet in NBR/GO are simultaneously hydrogenated and reduced through the synergistic hydrazine hydrate/hydrogen peroxide/copper sulfate catalytic system to prepare hydrogenated NBR (HNBR) and HNBR/reduced GO (RGO) nanocomposites. The degree of hydrogenation of the product is improved and the gel content of the product is reduced, which effectively solves the problems of the low degree of hydrogenation and high gel content in the diimide catalytic hydrogenation system. At the same time, the HNBR and HNBR/RGO nanocomposites, which are co-reduced by tea polyphenols and vitamin C, have good thermal stability and mechanical properties. Tea polyphenols are more likely to participate in the hydrogenation reaction. The degree of hydrogenation of the NBR double bonds is higher than the amount of reduction occurring within the GO sheet with the addition of tea polyphenols.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48871299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianan Yi, Erin P. Keaney, Jinde Zhang, C. Hansen, W. Zukas, J. Mead
Interlayer adhesion between distinct rubber compositions in elastomeric laminates has been pursued by a variety of approaches, including treating surfaces, introducing assistant chemicals, and interposing a “transition layer.” Each approach, however, may be specific to the elastomer chemistries and may not be easily transferred to other rubber composition pairs in laminates. These limitations were overcome by inserting a layer at the interface that is a blend of each of the elastomer compositions of the adjacent layers and that increases the interfacial adhesion strength of the resultant laminates. This approach was demonstrated using three elastomer systems: fluoroelastomer (FKM), acrylonitrile–butadiene rubber (NBR), and isobutylene–isoprene rubber (IIR). The adhesion in the three-layer laminate (FKM/NBR/IIR) was improved with the addition of an FKM-NBR blend layer between the FKM and NBR layers and the addition of an NBR-IIR blend layer between the NBR and IIR layers. The five-layer laminate (FKM/[FKM-NBR blend]/NBR/[NBR-IIR blend]/IIR) was also fabricated. Interfacial adhesion was evaluated using the T-peel test according to ASTM D1876, which showed that the blends provided improved adhesion. Scanning electron microscope images were used to study the interface region. The proposed idea offers a general approach to improve interfacial strength that is widely applicable to other multilayer elastomer laminates.
{"title":"IMPROVED ADHESION IN ELASTOMERIC LAMINATES USING ELASTOMER BLENDS","authors":"Jianan Yi, Erin P. Keaney, Jinde Zhang, C. Hansen, W. Zukas, J. Mead","doi":"10.5254/rct.22.78968","DOIUrl":"https://doi.org/10.5254/rct.22.78968","url":null,"abstract":"\u0000 Interlayer adhesion between distinct rubber compositions in elastomeric laminates has been pursued by a variety of approaches, including treating surfaces, introducing assistant chemicals, and interposing a “transition layer.” Each approach, however, may be specific to the elastomer chemistries and may not be easily transferred to other rubber composition pairs in laminates. These limitations were overcome by inserting a layer at the interface that is a blend of each of the elastomer compositions of the adjacent layers and that increases the interfacial adhesion strength of the resultant laminates. This approach was demonstrated using three elastomer systems: fluoroelastomer (FKM), acrylonitrile–butadiene rubber (NBR), and isobutylene–isoprene rubber (IIR). The adhesion in the three-layer laminate (FKM/NBR/IIR) was improved with the addition of an FKM-NBR blend layer between the FKM and NBR layers and the addition of an NBR-IIR blend layer between the NBR and IIR layers. The five-layer laminate (FKM/[FKM-NBR blend]/NBR/[NBR-IIR blend]/IIR) was also fabricated. Interfacial adhesion was evaluated using the T-peel test according to ASTM D1876, which showed that the blends provided improved adhesion. Scanning electron microscope images were used to study the interface region. The proposed idea offers a general approach to improve interfacial strength that is widely applicable to other multilayer elastomer laminates.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46484743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magnetorheological elastomers (MREs) are a kind of active control smart material, and their critical problem is that their ferromagnetic particles are too large, which causes holes to develop and results in MREs with poor mechanical performance and fatigue resistance. In this work, liquid butadiene acrylonitrile rubber (NBR)-synthesized phenolic resin microcapsules were synthesized and applied to MREs as a self-healing agent, effectively reducing the number of holes caused by ferromagnetic particles. The structure of the self-healing agent was determined by Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results indicated that a self-healing agent was successfully synthesized, the core of the capsule was spherical liquid nitrile rubber, and the wall of the capsule was composed of phenolic resin microspheres. Furthermore, the SEM images of the MREs showed that the number of cavities caused by ferromagnetic particles was greatly reduced after the addition of the self-healing agent, and the X-ray photoelectron spectroscopy (XPS) results of the MREs indicated the formation of a chemical bond between Fe and O. In addition, the mechanical properties and fatigue resistance of the MRE materials with the self-healing agent were improved. Under 100% strain and with the same number of cycles, the crack growth rate of MREs without self-healing agent is faster by about 329%, and the crack length is longer by about 220% than those of MREs with self-healing agent.
{"title":"PREPARATION AND CHARACTERIZATION OF SELF-HEALING MAGNETORHEOLOGICAL ELASTOMERS","authors":"J. Wang, Q. Zhang, J. Lv, Y. T. Wei","doi":"10.5254/rct.22.78927","DOIUrl":"https://doi.org/10.5254/rct.22.78927","url":null,"abstract":"\u0000 Magnetorheological elastomers (MREs) are a kind of active control smart material, and their critical problem is that their ferromagnetic particles are too large, which causes holes to develop and results in MREs with poor mechanical performance and fatigue resistance. In this work, liquid butadiene acrylonitrile rubber (NBR)-synthesized phenolic resin microcapsules were synthesized and applied to MREs as a self-healing agent, effectively reducing the number of holes caused by ferromagnetic particles. The structure of the self-healing agent was determined by Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results indicated that a self-healing agent was successfully synthesized, the core of the capsule was spherical liquid nitrile rubber, and the wall of the capsule was composed of phenolic resin microspheres. Furthermore, the SEM images of the MREs showed that the number of cavities caused by ferromagnetic particles was greatly reduced after the addition of the self-healing agent, and the X-ray photoelectron spectroscopy (XPS) results of the MREs indicated the formation of a chemical bond between Fe and O. In addition, the mechanical properties and fatigue resistance of the MRE materials with the self-healing agent were improved. Under 100% strain and with the same number of cycles, the crack growth rate of MREs without self-healing agent is faster by about 329%, and the crack length is longer by about 220% than those of MREs with self-healing agent.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41277447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Parisi, S. Coppola, S. Righi, Giacomo Gagliardi, F. Grasso, F. Bacchelli
Extensional deformations represent an effective stimulus to explore the rich rheological response of branched polymers and elastomers, enabling the design of polymers with specific molecular structure. However, probing the polymer behavior at large deformations is often limited by the experimental devices. We here present an alternative use of the Sentmanat Extensional Rheometer (SER) that allows Hencky strain units much larger than the maximum value achievable, ∼3.6. The proposed procedure consists of an oblique positioning of the sample in the measuring area. If a small inclination of the sample is used, the departure from the ideal uniaxial flow is negligible at Hencky strains <1, and nearly zero for larger values. Experimental results in the linear viscoelastic regime are compared with the double reptation model in order to discern polydispersity and branching effects, whereas the extensional rheology data are contrasted with the molecular stress function theory (MSF), revealing important information about the polymer structure, especially on the long-chain branching (LCB). Finally, the analysis of sample failure upon elongation allowed us to correlate the polymer structure to the rheological behavior during mixing processes.
{"title":"ALTERNATIVE USE OF THE SENTMANAT EXTENSIONAL RHEOMETER TO INVESTIGATE THE RHEOLOGICAL BEHAVIOR OF INDUSTRIAL RUBBERS AT VERY LARGE DEFORMATIONS","authors":"D. Parisi, S. Coppola, S. Righi, Giacomo Gagliardi, F. Grasso, F. Bacchelli","doi":"10.5254/rct.21.77948","DOIUrl":"https://doi.org/10.5254/rct.21.77948","url":null,"abstract":"\u0000 Extensional deformations represent an effective stimulus to explore the rich rheological response of branched polymers and elastomers, enabling the design of polymers with specific molecular structure. However, probing the polymer behavior at large deformations is often limited by the experimental devices. We here present an alternative use of the Sentmanat Extensional Rheometer (SER) that allows Hencky strain units much larger than the maximum value achievable, ∼3.6. The proposed procedure consists of an oblique positioning of the sample in the measuring area. If a small inclination of the sample is used, the departure from the ideal uniaxial flow is negligible at Hencky strains <1, and nearly zero for larger values. Experimental results in the linear viscoelastic regime are compared with the double reptation model in order to discern polydispersity and branching effects, whereas the extensional rheology data are contrasted with the molecular stress function theory (MSF), revealing important information about the polymer structure, especially on the long-chain branching (LCB). Finally, the analysis of sample failure upon elongation allowed us to correlate the polymer structure to the rheological behavior during mixing processes.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42577640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Ikeda, K. Miyaji, T. Ohashi, T. Nakajima, P. Junkong
Sulfur cross-linking reagents play critical roles not only in cross-linking rubber chains but also in controlling network morphology for reinforcement of rubber. Zinc oxide (ZnO) is clearly discovered as the main component for both roles. Especially, the importance of network inhomogeneity, which is significantly governed by the dispersion of ZnO particles, is emphasized for reinforcing rubber materials. Specifically, the formation of network domains and their continuous structures is discussed by combining the mechanical properties of the vulcanizates from the viewpoint of the reinforcement effect of rubber. Two continuous structures of network domains are termed as the network-domain cluster and network-domain network, which are observed by atomic force microscopy. The ZnO particles play a role as template for the formation of the continuous structures of network domains. The findings provide us with a practical hint for producing high-performance rubber materials.
{"title":"VULCANIZATION FOR REINFORCEMENT OF RUBBER","authors":"Y. Ikeda, K. Miyaji, T. Ohashi, T. Nakajima, P. Junkong","doi":"10.5254/rct.22.77939","DOIUrl":"https://doi.org/10.5254/rct.22.77939","url":null,"abstract":"\u0000 Sulfur cross-linking reagents play critical roles not only in cross-linking rubber chains but also in controlling network morphology for reinforcement of rubber. Zinc oxide (ZnO) is clearly discovered as the main component for both roles. Especially, the importance of network inhomogeneity, which is significantly governed by the dispersion of ZnO particles, is emphasized for reinforcing rubber materials. Specifically, the formation of network domains and their continuous structures is discussed by combining the mechanical properties of the vulcanizates from the viewpoint of the reinforcement effect of rubber. Two continuous structures of network domains are termed as the network-domain cluster and network-domain network, which are observed by atomic force microscopy. The ZnO particles play a role as template for the formation of the continuous structures of network domains. The findings provide us with a practical hint for producing high-performance rubber materials.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41572855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Kruželák, Andrea Kvasničáková, Klaudia Hložeková, Michaela Džuganová, Jana Gregorová, J. Vilčáková, Marek Gořalík, Ján Hronkovič, J. Preťo, I. Hudeč
Composites based on acrylonitrile–butadiene rubber, carbon nanotubes, and manganese–zinc ferrite were fabricated and tested for electromagnetic interference (EMI) absorption shielding. First, carbon nanotubes and ferrite were solely used for the preparation of rubber composites. Then, carbon nanotubes were combined with magnetic filler and incorporated into the rubber matrix. The results revealed that carbon nanotubes act as reinforcing filler and significantly enhance the physical–mechanical properties of composites. The presence of carbon nanotubes in the rubber matrix also results in an outstanding increase in electrical conductivity and permittivity of composite materials, as a consequence of which the EMI absorption shielding was poor in the tested frequency range of 1 MHz to 3 GHz. On the other hand, ferrite-filled composites are able to efficiently absorb electromagnetic radiation emitted from various electronic and radiation sources. However, the tensile strength of the composites showed a decreasing trend with increasing content of ferrite. The combination of carbon nanotubes with manganese–zinc ferrite resulted in an improvement in the physical–mechanical properties of hybrid composites. As the permittivity of hybrid composites was still much higher in comparison with those filled only with ferrite, only the composite filled with 5 phr of carbon nanotubes and 100 phr of ferrite showed a slight EMI absorption shielding ability over the tested frequency range.
{"title":"ELECTROMAGNETIC ABSORPTION CHARACTERISTICS OF MANGANESE–ZINC FERRITE AND MULTIWALLED CARBON NANOTUBE–FILLED COMPOSITES BASED ON NBR","authors":"J. Kruželák, Andrea Kvasničáková, Klaudia Hložeková, Michaela Džuganová, Jana Gregorová, J. Vilčáková, Marek Gořalík, Ján Hronkovič, J. Preťo, I. Hudeč","doi":"10.5254/rct.22.77986","DOIUrl":"https://doi.org/10.5254/rct.22.77986","url":null,"abstract":"\u0000 Composites based on acrylonitrile–butadiene rubber, carbon nanotubes, and manganese–zinc ferrite were fabricated and tested for electromagnetic interference (EMI) absorption shielding. First, carbon nanotubes and ferrite were solely used for the preparation of rubber composites. Then, carbon nanotubes were combined with magnetic filler and incorporated into the rubber matrix. The results revealed that carbon nanotubes act as reinforcing filler and significantly enhance the physical–mechanical properties of composites. The presence of carbon nanotubes in the rubber matrix also results in an outstanding increase in electrical conductivity and permittivity of composite materials, as a consequence of which the EMI absorption shielding was poor in the tested frequency range of 1 MHz to 3 GHz. On the other hand, ferrite-filled composites are able to efficiently absorb electromagnetic radiation emitted from various electronic and radiation sources. However, the tensile strength of the composites showed a decreasing trend with increasing content of ferrite. The combination of carbon nanotubes with manganese–zinc ferrite resulted in an improvement in the physical–mechanical properties of hybrid composites. As the permittivity of hybrid composites was still much higher in comparison with those filled only with ferrite, only the composite filled with 5 phr of carbon nanotubes and 100 phr of ferrite showed a slight EMI absorption shielding ability over the tested frequency range.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44333612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Uniaxial tension tests on dumbbells are routinely used to determine the stress–strain response of engineering materials. The simplest way to calculate strain is from grip displacement during extension, but this introduces significant error when dumbbells are gripped at the wider end sections to avoid the sample breaking prematurely in the grips. Mechanical and optical extensometers alleviate this problem by directly measuring strain in the gauge section. However, the equipment introduces significant additional hardware and software costs, and some experimental setups obstruct or prevent direct measurement of strain. The strain following systems also struggle both with the loss in mark intensity and changes of the shape of the marked point as the strain level is increased. To address these shortcomings, a novel analytical model to correct stress–strain data based on grip displacement is proposed. The model is implemented in Fortran and applied to hyperelastic materials which are assumed isotropic, but in principle the method is not restricted to elastomers. The model is validated with three studies on dumbbells: (i) a finite-element analysis for strains up to 660%; (ii) an experimental test with unfilled natural rubber up to 300% strain using a video extensometer; and (iii) a high temperature experimental test to fracture where the strain is corrected for a filled rubber. The model errors range from 2.2% to 3.1%, which is well within material and experimental uncertainties; hence, the model provides an accurate, inexpensive means of determining stress–strain behavior from grip displacement.
{"title":"METHOD TO GENERATE ACCURATE ELASTIC AND HYPERELASTIC UNIAXIAL TENSION STRESS–STRAIN DATA WITHOUT AN EXTENSOMETER","authors":"T. Hohenberger, J. Busfield","doi":"10.5254/rct.21.78992","DOIUrl":"https://doi.org/10.5254/rct.21.78992","url":null,"abstract":"\u0000 Uniaxial tension tests on dumbbells are routinely used to determine the stress–strain response of engineering materials. The simplest way to calculate strain is from grip displacement during extension, but this introduces significant error when dumbbells are gripped at the wider end sections to avoid the sample breaking prematurely in the grips. Mechanical and optical extensometers alleviate this problem by directly measuring strain in the gauge section. However, the equipment introduces significant additional hardware and software costs, and some experimental setups obstruct or prevent direct measurement of strain. The strain following systems also struggle both with the loss in mark intensity and changes of the shape of the marked point as the strain level is increased. To address these shortcomings, a novel analytical model to correct stress–strain data based on grip displacement is proposed. The model is implemented in Fortran and applied to hyperelastic materials which are assumed isotropic, but in principle the method is not restricted to elastomers. The model is validated with three studies on dumbbells: (i) a finite-element analysis for strains up to 660%; (ii) an experimental test with unfilled natural rubber up to 300% strain using a video extensometer; and (iii) a high temperature experimental test to fracture where the strain is corrected for a filled rubber. The model errors range from 2.2% to 3.1%, which is well within material and experimental uncertainties; hence, the model provides an accurate, inexpensive means of determining stress–strain behavior from grip displacement.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44079249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The strain rate dependence of uncured rubber is investigated through a series of tensile tests (monotonic, multistep relaxation, cyclic creep tests) at different strain rates. In addition, loading/unloading tests in which the strain rate is varied every cycle are carried out to observe their dependence on the deformation history. A strain rate–dependent viscoelastic–viscoplastic constitutive model is proposed with the nonlinear viscosity and process-dependent recovery properties observed in the test results. Those properties are implemented by introducing evolution equations for additional internal variables. The identified material parameters capture the experiments qualitatively well. The proposed model is also evaluated by finite element simulations of the building process of a tire, followed by the in-molding.
{"title":"STRAIN RATE–DEPENDENT BEHAVIOR OF UNCURED RUBBER: EXPERIMENTAL INVESTIGATION AND CONSTITUTIVE MODELING","authors":"Sanghyeub Kim, T. Berger, M. Kaliske","doi":"10.5254/rct.21.78981","DOIUrl":"https://doi.org/10.5254/rct.21.78981","url":null,"abstract":"The strain rate dependence of uncured rubber is investigated through a series of tensile tests (monotonic, multistep relaxation, cyclic creep tests) at different strain rates. In addition, loading/unloading tests in which the strain rate is varied every cycle are carried out to observe their dependence on the deformation history. A strain rate–dependent viscoelastic–viscoplastic constitutive model is proposed with the nonlinear viscosity and process-dependent recovery properties observed in the test results. Those properties are implemented by introducing evolution equations for additional internal variables. The identified material parameters capture the experiments qualitatively well. The proposed model is also evaluated by finite element simulations of the building process of a tire, followed by the in-molding.","PeriodicalId":21349,"journal":{"name":"Rubber Chemistry and Technology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43108071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：