Pub Date : 2023-04-04DOI: 10.1080/00218464.2022.2056027
Guilherme Garcia Momm, D. Fleming
ABSTRACT Durability issues associated with adhesive degradation have hindered widespread use of bonding in aircraft applications and contributed to several bond-related in-service accidents, fostering extensive related research. While the non-destructive evaluation (NDE) of bondline quality remains elusive, some authors suggested that NDE could establish bond strength thresholds, supporting the theoretical concept of a residual effective bond overlap (REBO). These authors related strength thresholds to NDE of specimens with artificial weak bonds only phenomenologically. This work proposes two physical-based approaches, combining NDE with analytical models for stress analysis, to estimate the residual strength of environmentally degraded metallic bonded joints considering an approximated REBO. These approaches incorporate fundamental characteristics of two physically distinct NDE techniques and a water-related aging mechanism. Statistically treated experimental data for verification was obtained from aluminum-epoxy bonded joints typical of aeronautic application. Two sets of these joints were exposed in a hot/wet controlled environment – to induce representative degradations – for different periods, non-destructively inspected, and mechanically tested. Each set of specimens differed only in the surface preparation to prompt dissimilar failure modes – adhesion and cohesion failures. Estimated residual strengths for different levels of degradation and failure modes were in agreement with quasi-static loads in a conservative fashion.
{"title":"Estimate residual strength of degraded bonded joints by combining analytical models with non-destructive evaluations","authors":"Guilherme Garcia Momm, D. Fleming","doi":"10.1080/00218464.2022.2056027","DOIUrl":"https://doi.org/10.1080/00218464.2022.2056027","url":null,"abstract":"ABSTRACT Durability issues associated with adhesive degradation have hindered widespread use of bonding in aircraft applications and contributed to several bond-related in-service accidents, fostering extensive related research. While the non-destructive evaluation (NDE) of bondline quality remains elusive, some authors suggested that NDE could establish bond strength thresholds, supporting the theoretical concept of a residual effective bond overlap (REBO). These authors related strength thresholds to NDE of specimens with artificial weak bonds only phenomenologically. This work proposes two physical-based approaches, combining NDE with analytical models for stress analysis, to estimate the residual strength of environmentally degraded metallic bonded joints considering an approximated REBO. These approaches incorporate fundamental characteristics of two physically distinct NDE techniques and a water-related aging mechanism. Statistically treated experimental data for verification was obtained from aluminum-epoxy bonded joints typical of aeronautic application. Two sets of these joints were exposed in a hot/wet controlled environment – to induce representative degradations – for different periods, non-destructively inspected, and mechanically tested. Each set of specimens differed only in the surface preparation to prompt dissimilar failure modes – adhesion and cohesion failures. Estimated residual strengths for different levels of degradation and failure modes were in agreement with quasi-static loads in a conservative fashion.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42524919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-28DOI: 10.1080/00218464.2023.2195556
T. Schmolke, D. Teutenberg, G. Meschut
ABSTRACT Due to increasing legal requirements to reduce emissions from vehicle fleets, vehicle manufacturers are focusing on the electrification of the powertrain. In entirely electrically driven vehicles, the energy is stored in traction batteries integrated below the passenger cell between the axles and thus located in the vehicle’s wet area. Therefore, high requirements apply to the protection of the sensitive cells against mechanical stress as well as against moisture penetration. In addition, one of the main requirements for the connections of the battery housing is to ensure gas tightness over the entire service life. Adhesive bonding technology as a planar joining process offers the potential to produce functionally tight connections. However, there is a lack of reliable test methods for validating the long-term tightness of structural adhesive joints under mechanical and corrosive loads. For this reason, the paper deals with developing a test concept with laboratory-scale test specimens for leak testing under mechanical loading. Various leakage test methods investigate the leakage rate of structurally bonded joints. An analysis of the leakage rate under superimposed cyclic mechanical shear tensile loading follows this. The test method is validated on a specially developed sample battery housing on a laboratory scale.
{"title":"Investigation of the leak tightness of structural adhesive joints for use in battery housings considering mechanical and corrosive loads","authors":"T. Schmolke, D. Teutenberg, G. Meschut","doi":"10.1080/00218464.2023.2195556","DOIUrl":"https://doi.org/10.1080/00218464.2023.2195556","url":null,"abstract":"ABSTRACT Due to increasing legal requirements to reduce emissions from vehicle fleets, vehicle manufacturers are focusing on the electrification of the powertrain. In entirely electrically driven vehicles, the energy is stored in traction batteries integrated below the passenger cell between the axles and thus located in the vehicle’s wet area. Therefore, high requirements apply to the protection of the sensitive cells against mechanical stress as well as against moisture penetration. In addition, one of the main requirements for the connections of the battery housing is to ensure gas tightness over the entire service life. Adhesive bonding technology as a planar joining process offers the potential to produce functionally tight connections. However, there is a lack of reliable test methods for validating the long-term tightness of structural adhesive joints under mechanical and corrosive loads. For this reason, the paper deals with developing a test concept with laboratory-scale test specimens for leak testing under mechanical loading. Various leakage test methods investigate the leakage rate of structurally bonded joints. An analysis of the leakage rate under superimposed cyclic mechanical shear tensile loading follows this. The test method is validated on a specially developed sample battery housing on a laboratory scale.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41551941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-26DOI: 10.1080/00218464.2023.2194535
P. Fernando, L. Antonino, G. E. Garcia, Rogerio R. de Sousa Júnior, Antonio V. Neto, F. Y. Nakamoto, D. J. dos Santos
ABSTRACT Several lignin-based adhesives were developed during the last decades. More recently, lignin isolation methods were improved, leading to technical grade lignins with constant properties. This recent scenario created the required conditions for the industrial use of lignin in adhesive applications, at large scale, with reliable properties. In this work, technical grade kraft lignin was epoxidized and incorporated in industrial epoxy resin, resulting into a partly biobased epoxy resin. Notwithstanding, the mechanical properties of cured partly biobased epoxy were investigated using Arcan device, aiming to reproduce realistic load conditions for the adhesively bonded joints. At last, failure envelopes were obtained from Drucker–Prager and von Mises models, revealing the most reliable model to calculate the failure prediction. Results pointed out to the development of a partly biobased epoxy adhesive with slightly superior mechanical properties, in comparison with industrial epoxy adhesive. Indeed, an important contribution was provided for the lignin revalorization and the mechanical characterization and failure prediction of epoxy adhesive based on the modified lignin.
{"title":"Effects of the incorporation of modified kraft lignin on the mechanical properties of epoxy adhesive: experimental and theoretical approaches","authors":"P. Fernando, L. Antonino, G. E. Garcia, Rogerio R. de Sousa Júnior, Antonio V. Neto, F. Y. Nakamoto, D. J. dos Santos","doi":"10.1080/00218464.2023.2194535","DOIUrl":"https://doi.org/10.1080/00218464.2023.2194535","url":null,"abstract":"ABSTRACT Several lignin-based adhesives were developed during the last decades. More recently, lignin isolation methods were improved, leading to technical grade lignins with constant properties. This recent scenario created the required conditions for the industrial use of lignin in adhesive applications, at large scale, with reliable properties. In this work, technical grade kraft lignin was epoxidized and incorporated in industrial epoxy resin, resulting into a partly biobased epoxy resin. Notwithstanding, the mechanical properties of cured partly biobased epoxy were investigated using Arcan device, aiming to reproduce realistic load conditions for the adhesively bonded joints. At last, failure envelopes were obtained from Drucker–Prager and von Mises models, revealing the most reliable model to calculate the failure prediction. Results pointed out to the development of a partly biobased epoxy adhesive with slightly superior mechanical properties, in comparison with industrial epoxy adhesive. Indeed, an important contribution was provided for the lignin revalorization and the mechanical characterization and failure prediction of epoxy adhesive based on the modified lignin.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45909171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-24DOI: 10.1080/00218464.2023.2194534
Ting-Ting Wang, Yi-Ran Li, Ganyun Huang
ABSTRACT In the present work, adhesion has been incorporated in a model for receding contact between an elastic layer and a half plane under flat and parabolic punches. Based on the JKR model for adhesion and with the help of integral transformation, solution of the problem may be reduced to a system of singular integral equations. A numerical scheme has been proposed and verified. The effect of adhesion on contact size and the stresses has been demonstrated.
{"title":"Effect of adhesion on the frictionless receding contact between an elastic layer and a substrate","authors":"Ting-Ting Wang, Yi-Ran Li, Ganyun Huang","doi":"10.1080/00218464.2023.2194534","DOIUrl":"https://doi.org/10.1080/00218464.2023.2194534","url":null,"abstract":"ABSTRACT In the present work, adhesion has been incorporated in a model for receding contact between an elastic layer and a half plane under flat and parabolic punches. Based on the JKR model for adhesion and with the help of integral transformation, solution of the problem may be reduced to a system of singular integral equations. A numerical scheme has been proposed and verified. The effect of adhesion on contact size and the stresses has been demonstrated.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43227007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-16DOI: 10.1080/00218464.2023.2190895
Reza Shiri, Ali Ahmadi-Dehnoei, S. Ghasemirad
ABSTRACT Regular surface roughness could be created on the surface of a pressure-sensitive adhesive (PSA) film through Marangoni flow during the drying process. Therefore, tailoring of both surface and bulk characteristics of the PSA and consequently its adhesion strength could be expected by controlling the drying conditions. Herein, surface and bulk properties of a water-based PSA dried at various temperatures and humidities were scrutinized. Increase in the drying temperature improved the adhesion strength of the PSA to poly(ethylene terephthalate) due to enhanced surface nanoroughness of its film. At constant humidity, the higher the Péclet number, the higher the Marangoni number and the rougher the PSA film surface. Drying humidity rise, however, improved the adhesion strength due to more uniform distribution of copolymers constituting the PSA, better interdiffusion of chains through the interface of polymer particles in a prolonged drying process, and increased surface free energy of the film. The adhesion strength of the PSA, similar to the here-defined viscoelastic dissipation ability, demonstrated a power dependence on the film surface nanoroughness. This newly-defined parameter considers taking advantage of the real viscoelastic dissipation of the PSA regarding its potentiality through thorough wetting of the substrate surface with the PSA.
{"title":"Effect of drying conditions on adhesion strength of a pressure-sensitive adhesive","authors":"Reza Shiri, Ali Ahmadi-Dehnoei, S. Ghasemirad","doi":"10.1080/00218464.2023.2190895","DOIUrl":"https://doi.org/10.1080/00218464.2023.2190895","url":null,"abstract":"ABSTRACT Regular surface roughness could be created on the surface of a pressure-sensitive adhesive (PSA) film through Marangoni flow during the drying process. Therefore, tailoring of both surface and bulk characteristics of the PSA and consequently its adhesion strength could be expected by controlling the drying conditions. Herein, surface and bulk properties of a water-based PSA dried at various temperatures and humidities were scrutinized. Increase in the drying temperature improved the adhesion strength of the PSA to poly(ethylene terephthalate) due to enhanced surface nanoroughness of its film. At constant humidity, the higher the Péclet number, the higher the Marangoni number and the rougher the PSA film surface. Drying humidity rise, however, improved the adhesion strength due to more uniform distribution of copolymers constituting the PSA, better interdiffusion of chains through the interface of polymer particles in a prolonged drying process, and increased surface free energy of the film. The adhesion strength of the PSA, similar to the here-defined viscoelastic dissipation ability, demonstrated a power dependence on the film surface nanoroughness. This newly-defined parameter considers taking advantage of the real viscoelastic dissipation of the PSA regarding its potentiality through thorough wetting of the substrate surface with the PSA.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47957352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-12DOI: 10.1080/00218464.2023.2187293
Andreea Tintatu, C. Bădulescu, P. Bidaud, Philippe Le Grognec, J. Adrien, E. Maire, Hervé Bindi, C. Coguenanff
ABSTRACT This work aims to characterize the water uptake mechanisms of a two-component epoxy adhesive joint immersed in deionized water. The pore-type defects in the bulk adhesive after the cure cycle are highlighted and characterized using X-ray µ-tomography. Two population patterns of defects are generated and analyzed, for two different thicknesses. The waterfront is not detectable by µ-tomography for this adhesive because the densities of the water and the adhesive remain relatively close to each other. Instead, the volume variation and kinetics of pore water filling have been accurately identified. This analysis was completed by optical observations and gravimetric measurements.
{"title":"Understanding of water uptake mechanisms in an epoxy joint characterized by pore-type defects","authors":"Andreea Tintatu, C. Bădulescu, P. Bidaud, Philippe Le Grognec, J. Adrien, E. Maire, Hervé Bindi, C. Coguenanff","doi":"10.1080/00218464.2023.2187293","DOIUrl":"https://doi.org/10.1080/00218464.2023.2187293","url":null,"abstract":"ABSTRACT This work aims to characterize the water uptake mechanisms of a two-component epoxy adhesive joint immersed in deionized water. The pore-type defects in the bulk adhesive after the cure cycle are highlighted and characterized using X-ray µ-tomography. Two population patterns of defects are generated and analyzed, for two different thicknesses. The waterfront is not detectable by µ-tomography for this adhesive because the densities of the water and the adhesive remain relatively close to each other. Instead, the volume variation and kinetics of pore water filling have been accurately identified. This analysis was completed by optical observations and gravimetric measurements.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47364456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-07DOI: 10.1080/00218464.2023.2186226
Zenghua Fan, Zixiao Liu, Congcong Huang, Han Wang, Ming Fan, Lefeng Wang
ABSTRACT The presence of surface tension in liquids, which induces a strong capillary force between wetting particles in micro/nano scale, has aroused extensive attention. In present study, a fundamental investigation on capillary forces and rupture behaviors of capillary bridges between a three-finger microgripper and a plate is conducted in quasi-static state. Theoretical analysis is performed for solutions of the capillary force. The capillary bridges between a three-finger microgripper and a plate are established based on the principle of energy minimization. An analytical approach for computing the capillary force for the three-finger/plate geometry is proposed by means of variables obtained from the simulation models. The comparison of the single-finger capillary bridge and three-finger capillary bridge is investigated based on the developed models. The effects of separation distance, capillary bridge volume, radial distance and contact angle on the capillary force of three-finger capillary bridges are analyzed in detail. The results demonstrate that the variation of capillary force with separation distance and volume changing is not monotonic, which is caused by the edge effect of the three-finger microgripper. Capillary force measurements were experimentally characterized to demonstrate the reliability of the simulation models and the capillary force solution method based on an established experimental platform.
{"title":"Capillary forces and capillary bridges between a three-finger microgripper and a plate","authors":"Zenghua Fan, Zixiao Liu, Congcong Huang, Han Wang, Ming Fan, Lefeng Wang","doi":"10.1080/00218464.2023.2186226","DOIUrl":"https://doi.org/10.1080/00218464.2023.2186226","url":null,"abstract":"ABSTRACT The presence of surface tension in liquids, which induces a strong capillary force between wetting particles in micro/nano scale, has aroused extensive attention. In present study, a fundamental investigation on capillary forces and rupture behaviors of capillary bridges between a three-finger microgripper and a plate is conducted in quasi-static state. Theoretical analysis is performed for solutions of the capillary force. The capillary bridges between a three-finger microgripper and a plate are established based on the principle of energy minimization. An analytical approach for computing the capillary force for the three-finger/plate geometry is proposed by means of variables obtained from the simulation models. The comparison of the single-finger capillary bridge and three-finger capillary bridge is investigated based on the developed models. The effects of separation distance, capillary bridge volume, radial distance and contact angle on the capillary force of three-finger capillary bridges are analyzed in detail. The results demonstrate that the variation of capillary force with separation distance and volume changing is not monotonic, which is caused by the edge effect of the three-finger microgripper. Capillary force measurements were experimentally characterized to demonstrate the reliability of the simulation models and the capillary force solution method based on an established experimental platform.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59097191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-03DOI: 10.1080/00218464.2023.2185142
Reinosuke Kusano, Y. Kusano
ABSTRACT Surface tensions of solid materials have been studied over 200 years and widely used for industrial or engineering applications. The surface tensions and surface tension components can be calculated using measured contact angles, for example, by the model studied by Owens and Wendt. The model is often represented in an asymmetric linear form, called the Owens-Wendt-Rabel-Kaelble method, with the use of the linear least squares method. However, due to the practical preference not to use many types of test liquids, the existing statistical analysis is unsuitable, especially when the data measured are scattered. The present work proposes symmetric linear and circular expressions of the model of the two surface tension components. The symmetric linear expression can be used for obtaining the polar and dispersion components of surface tension of a solid; it enables appropriate choices for test liquids, physically meaningful screening of measured values, and clear validation of deduced surface tension components of solids. The symmetric circular expressions can be applied to deduce polar and dispersion components of liquids by using test solids. In conjunction with this, appropriate choices of test solids can be determined.
{"title":"Symmetric expressions of surface tension components","authors":"Reinosuke Kusano, Y. Kusano","doi":"10.1080/00218464.2023.2185142","DOIUrl":"https://doi.org/10.1080/00218464.2023.2185142","url":null,"abstract":"ABSTRACT Surface tensions of solid materials have been studied over 200 years and widely used for industrial or engineering applications. The surface tensions and surface tension components can be calculated using measured contact angles, for example, by the model studied by Owens and Wendt. The model is often represented in an asymmetric linear form, called the Owens-Wendt-Rabel-Kaelble method, with the use of the linear least squares method. However, due to the practical preference not to use many types of test liquids, the existing statistical analysis is unsuitable, especially when the data measured are scattered. The present work proposes symmetric linear and circular expressions of the model of the two surface tension components. The symmetric linear expression can be used for obtaining the polar and dispersion components of surface tension of a solid; it enables appropriate choices for test liquids, physically meaningful screening of measured values, and clear validation of deduced surface tension components of solids. The symmetric circular expressions can be applied to deduce polar and dispersion components of liquids by using test solids. In conjunction with this, appropriate choices of test solids can be determined.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42870423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-02DOI: 10.1080/00218464.2023.2181699
Runa Okumura, K. Shimamoto, Y. Sekiguchi, Kazushi Kimura, Hirokazu Kageyama, Yutaro Yamamoto, Y. Matsuki, C. Sato
ABSTRACT The mechanical properties of polyurethane compounds were experimentally investigated by changing the composition of their components. Polyol components (polyoxypropylene glycol: PPG, polyoxytetramethylene glycol: PTMG, and polycarbonatediol: PCD) were mixed with monomeric methylene diphenyl diisocyanate to synthesize polyurethane pre-polymer, mixed with chain extenders (1,4’-butanediol: 1,4’-BD or dimethylthiotoluene diamine: DMTDA), and cured, to prepare four types of polyurethane resins. Tensile tests were conducted using a mechanical testing machine with a strain rate of approximately 0.3 s−1 and a hydraulic high-speed tensile testing machine with a strain rate of approximately 500 s−1. The temperature was controlled to be −40°C, −10°C, or 25°C. When PTMG was used as the polyol, the stress-strain relationship was less sensitive to temperatures and loading rates, and the material properties exhibited a relatively good balance between elongation and strength. Additionally, the use of 1,4’-BD as a chain extender resulted in higher elongation and lower strength than the use of DMTDA. Conversely, the stress-strain relationship was dramatically altered by the test conditions when PPG and PCD were used as the polyol and embrittlement under a combination of low temperature and high strain rate was confirmed. Furthermore, there were certain compositional combinations that exhibit necking at low temperatures.
{"title":"Effects of low temperatures and high strain rates on the tensile properties of polyurethane polymers for adhesives","authors":"Runa Okumura, K. Shimamoto, Y. Sekiguchi, Kazushi Kimura, Hirokazu Kageyama, Yutaro Yamamoto, Y. Matsuki, C. Sato","doi":"10.1080/00218464.2023.2181699","DOIUrl":"https://doi.org/10.1080/00218464.2023.2181699","url":null,"abstract":"ABSTRACT The mechanical properties of polyurethane compounds were experimentally investigated by changing the composition of their components. Polyol components (polyoxypropylene glycol: PPG, polyoxytetramethylene glycol: PTMG, and polycarbonatediol: PCD) were mixed with monomeric methylene diphenyl diisocyanate to synthesize polyurethane pre-polymer, mixed with chain extenders (1,4’-butanediol: 1,4’-BD or dimethylthiotoluene diamine: DMTDA), and cured, to prepare four types of polyurethane resins. Tensile tests were conducted using a mechanical testing machine with a strain rate of approximately 0.3 s−1 and a hydraulic high-speed tensile testing machine with a strain rate of approximately 500 s−1. The temperature was controlled to be −40°C, −10°C, or 25°C. When PTMG was used as the polyol, the stress-strain relationship was less sensitive to temperatures and loading rates, and the material properties exhibited a relatively good balance between elongation and strength. Additionally, the use of 1,4’-BD as a chain extender resulted in higher elongation and lower strength than the use of DMTDA. Conversely, the stress-strain relationship was dramatically altered by the test conditions when PPG and PCD were used as the polyol and embrittlement under a combination of low temperature and high strain rate was confirmed. Furthermore, there were certain compositional combinations that exhibit necking at low temperatures.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43612017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-02DOI: 10.1080/00218464.2023.2184263
Zenghao Zhou, Liang Fu, Yaolong He, Hongjiu Hu
ABSTRACT The natural fibrous sepiolite is introduced into emulsion polymer isocyanate (EPI) consisting of aqueous vinyl acetate copolymer-based main component (MC) and polymeric methylene diisocyanate (pMDI) for the first time to prepare a high-performance, environmentally friendly, and cost-effective timber adhesive. We have studied the effect of the sepiolite content on the tensile stress-strain curves, dynamical mechanical properties, essential work of fracture of the cured glue layer, and the EPI bonding properties. In addition, we have also investigated the chemical group, fractional free volume, and morphology of EPI polymers with various sepiolite contents. The results indicate that adding sepiolite can significantly increase the tensile strength, elastic modulus, dynamic stiffness, and fracture toughness of cured EPI films. Remarkably, EPI-bonded structures exhibit superior resistance to compressive shear damage upon ageing in boiling water. For MC with 6.0–9.0 wt% sepiolite, only the addition of 10.0 wt% general pMDI crosslinker is required to achieve the JIS K6806 structural adhesive. The underlying enhancement mechanism is the significant hydrogen-bonding coupled chemical reaction capability of sepiolite for the available groups in the EPI system.
{"title":"Natural fibrous sepiolite-reinforced emulsion polymer isocyanate for timber structural adhesive","authors":"Zenghao Zhou, Liang Fu, Yaolong He, Hongjiu Hu","doi":"10.1080/00218464.2023.2184263","DOIUrl":"https://doi.org/10.1080/00218464.2023.2184263","url":null,"abstract":"ABSTRACT The natural fibrous sepiolite is introduced into emulsion polymer isocyanate (EPI) consisting of aqueous vinyl acetate copolymer-based main component (MC) and polymeric methylene diisocyanate (pMDI) for the first time to prepare a high-performance, environmentally friendly, and cost-effective timber adhesive. We have studied the effect of the sepiolite content on the tensile stress-strain curves, dynamical mechanical properties, essential work of fracture of the cured glue layer, and the EPI bonding properties. In addition, we have also investigated the chemical group, fractional free volume, and morphology of EPI polymers with various sepiolite contents. The results indicate that adding sepiolite can significantly increase the tensile strength, elastic modulus, dynamic stiffness, and fracture toughness of cured EPI films. Remarkably, EPI-bonded structures exhibit superior resistance to compressive shear damage upon ageing in boiling water. For MC with 6.0–9.0 wt% sepiolite, only the addition of 10.0 wt% general pMDI crosslinker is required to achieve the JIS K6806 structural adhesive. The underlying enhancement mechanism is the significant hydrogen-bonding coupled chemical reaction capability of sepiolite for the available groups in the EPI system.","PeriodicalId":14778,"journal":{"name":"Journal of Adhesion","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47381801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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