Mitsuharu Inaba, Y. Kimura, K. Nagata, K. Inomata, Kiyohisa Takahashi
Carbon black (CB)-filled composites of polyethylene (PE), polypropylene (PP), and PP/PE blend with weight composition of 40/60 have been prepared by twin screw extruder, and their electrical resistivities have been investigated. In order to improve the surface properties of CB, γ-aminopropyl trimethoxysilane (APS) was used for the surface treatment of CB. The surface treatment of CB by APS was found to effectively decrease percolation threshold, φc, i.e., the electrical resistivity showed drastic decrease when the CB content was larger than φ c. Temperature dependence of APS-treated CB/PP/PE composites exhibited almost constant electrical resistivity (~106 Ωcm) in the range of 25-130°C, and it was increased drastically to ~1012Ωcm above the melting temperature of PE, resulting high positive temperature coefficient (PTC) intensity (ca. 106). This high resistivity was maintained even at the higher temperature than 150°C, and only weak negative temperature coefficient (NTC) behavior was observed. The surface treatment of CB by APS is effective to obtain CB/PP/PE composites having excellent thermal electrical property as a switching material.
{"title":"Electrical Resistivity of PP/PE Composite Filled with Amino-silane Treated Carbon Black and Its Thermal Behavior","authors":"Mitsuharu Inaba, Y. Kimura, K. Nagata, K. Inomata, Kiyohisa Takahashi","doi":"10.1678/RHEOLOGY.32.129","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.32.129","url":null,"abstract":"Carbon black (CB)-filled composites of polyethylene (PE), polypropylene (PP), and PP/PE blend with weight composition of 40/60 have been prepared by twin screw extruder, and their electrical resistivities have been investigated. In order to improve the surface properties of CB, γ-aminopropyl trimethoxysilane (APS) was used for the surface treatment of CB. The surface treatment of CB by APS was found to effectively decrease percolation threshold, φc, i.e., the electrical resistivity showed drastic decrease when the CB content was larger than φ c. Temperature dependence of APS-treated CB/PP/PE composites exhibited almost constant electrical resistivity (~106 Ωcm) in the range of 25-130°C, and it was increased drastically to ~1012Ωcm above the melting temperature of PE, resulting high positive temperature coefficient (PTC) intensity (ca. 106). This high resistivity was maintained even at the higher temperature than 150°C, and only weak negative temperature coefficient (NTC) behavior was observed. The surface treatment of CB by APS is effective to obtain CB/PP/PE composites having excellent thermal electrical property as a switching material.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"11 1","pages":"129-132"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75362015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Viscoelastic effects on phase separations in polymeric systems are investigated by a numerical method using a two fluid model. In the viscoelastic phase separation, the coupling of solvent diffusion and stress stored in polymeric materials strongly influences the dynamics, morphology of phase separated pattern. In our model we take into account the coupling and explain unusual phase separation phenomena observed experimentally in polymer solution systems. In our simulations, we reproduced the network pattern of polymer rich phase which is a minority phase and found that the coarsening of the network pattern is very slow. In order to clarify the origin of slowing down of coarsening dynamics of network pattern of polymer rich phase,we investigated the dynamics of an initially elongated droplet.We found that the flow field induced by the surface tension of droplet is suppressed by the stress produced by the induced flow field.
{"title":"Theoretical and Numerical Studies on Viscoelastic Effect in Phase Separation of Polymeric Systems","authors":"T. Taniguchi","doi":"10.1678/RHEOLOGY.32.27","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.32.27","url":null,"abstract":"Viscoelastic effects on phase separations in polymeric systems are investigated by a numerical method using a two fluid model. In the viscoelastic phase separation, the coupling of solvent diffusion and stress stored in polymeric materials strongly influences the dynamics, morphology of phase separated pattern. In our model we take into account the coupling and explain unusual phase separation phenomena observed experimentally in polymer solution systems. In our simulations, we reproduced the network pattern of polymer rich phase which is a minority phase and found that the coarsening of the network pattern is very slow. In order to clarify the origin of slowing down of coarsening dynamics of network pattern of polymer rich phase,we investigated the dynamics of an initially elongated droplet.We found that the flow field induced by the surface tension of droplet is suppressed by the stress produced by the induced flow field.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"96 1","pages":"27-32"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76808353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flows of polymeric fluids and liquid crystalline polymers (LCPs) were studied in complex flow geometries. In the present paper, however, there is a focus on the flow analysis of the flow of LCPs. Numerical simulations of flows of LCPs were carried out using the modified Doi equation with the quadratic closure approximation. Molecular orientation of LCPs is strongly affected by the velocity field including both the shear and elongational flows in the complex geometry while the velocity distribution is modified by the molecular orientation. Numerical simulations for a flow between parallel plates containing a cylinder and a spinning flow are presented as examples. A novel rubbing-free alignment layer for LCs was proposed as an application of flow-induced molecular orientation of LCPs. The development of wavy texture in startup flows of LCPs through a slit cell was discussed.
{"title":"Analysis of Flows of Polymeric Solutions and Liquid Crystals","authors":"N. Mori","doi":"10.1678/RHEOLOGY.32.245","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.32.245","url":null,"abstract":"Flows of polymeric fluids and liquid crystalline polymers (LCPs) were studied in complex flow geometries. In the present paper, however, there is a focus on the flow analysis of the flow of LCPs. Numerical simulations of flows of LCPs were carried out using the modified Doi equation with the quadratic closure approximation. Molecular orientation of LCPs is strongly affected by the velocity field including both the shear and elongational flows in the complex geometry while the velocity distribution is modified by the molecular orientation. Numerical simulations for a flow between parallel plates containing a cylinder and a spinning flow are presented as examples. A novel rubbing-free alignment layer for LCs was proposed as an application of flow-induced molecular orientation of LCPs. The development of wavy texture in startup flows of LCPs through a slit cell was discussed.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"78 1","pages":"245-251"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78965133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kensuke Mizufune, K. Soma, K. Nagata, K. Inomata, Kiyohisa Takahashi
Poly(ethylene terephthalate) (PET) / poly(ethylene naphthalate) (PEN) blends with 50/50 composition have been prepared by melt-mixing at the temperatures above 280°C and subsequent heating at 280°C before hot-press molding. Progress of transesterification reaction and formation of PET-PEN random copolymers during these melt-blending processes have been confirmed by 1H-NMR measurement. Dynamic viscoelasticity, DSC thermograms, and SEM images for the PET/PEN blends with shorter heating time at 280°C suggested that the blend sample was in an immiscible state when the transesterification level (T) was less than 5%. With the increase of the heating time, the sample changed to miscible state with T > 5 % and exhibited transparency. The phase-separated morphology was fine and the size of the phase-separated domain was several hundred nanometer when T ≈ 5%. Flexural test for the blend samples revealed that the PET/PEN blends exhibited the maximum flexural strength when T ≈ 5 %. Increase in the melt-mixing temperature was found to accelerate the transesterification reaction, and to shorten the processing time to obtain the miscible PET/PEN blend.
{"title":"Transesterification Reaction and Morphology of PET/PEN Melt-mixed Blends and Their Flexural Strengths","authors":"Kensuke Mizufune, K. Soma, K. Nagata, K. Inomata, Kiyohisa Takahashi","doi":"10.1678/RHEOLOGY.32.133","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.32.133","url":null,"abstract":"Poly(ethylene terephthalate) (PET) / poly(ethylene naphthalate) (PEN) blends with 50/50 composition have been prepared by melt-mixing at the temperatures above 280°C and subsequent heating at 280°C before hot-press molding. Progress of transesterification reaction and formation of PET-PEN random copolymers during these melt-blending processes have been confirmed by 1H-NMR measurement. Dynamic viscoelasticity, DSC thermograms, and SEM images for the PET/PEN blends with shorter heating time at 280°C suggested that the blend sample was in an immiscible state when the transesterification level (T) was less than 5%. With the increase of the heating time, the sample changed to miscible state with T > 5 % and exhibited transparency. The phase-separated morphology was fine and the size of the phase-separated domain was several hundred nanometer when T ≈ 5%. Flexural test for the blend samples revealed that the PET/PEN blends exhibited the maximum flexural strength when T ≈ 5 %. Increase in the melt-mixing temperature was found to accelerate the transesterification reaction, and to shorten the processing time to obtain the miscible PET/PEN blend.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"56 1","pages":"133-137"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76195466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Japan Surfaces in polymeric materials play an important role in many technological applications. Hence, systematical understanding of aggregation states and physical properties at the surfaces is of pivotal importance as the first benchmark so that highly functionalized polymeric materials based on surface peculiarity can be promisingly designed and constructed. Nevertheless, surface properties, especially rheological properties, had not been studied until early 90s because of technical difficulties. In 1993, we started to embark on this intriguing and challenging issue by mainly scanning force microscopy using monodisperse polystyrene (PS) solid films. Consequently, conclusions obtained thus far are consistently arrived that molecular motion at the PS surfaces is thermally activated in comparison with the corresponding internal bulk region. However, it is far from clear for the moment what the whole picture of such peculiar surface mobility is, although we believe that some parts of it have been successfully clarified to date. Here, experimental methods to examine surface rheological properties, which we have proposed, are mentioned at first, and then, essential points of what we have established are
{"title":"Study on Surface Glass Transition Behavior in Monodisperse Polystyrene Films","authors":"Keiji Tanaka","doi":"10.1678/RHEOLOGY.32.17","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.32.17","url":null,"abstract":"Japan Surfaces in polymeric materials play an important role in many technological applications. Hence, systematical understanding of aggregation states and physical properties at the surfaces is of pivotal importance as the first benchmark so that highly functionalized polymeric materials based on surface peculiarity can be promisingly designed and constructed. Nevertheless, surface properties, especially rheological properties, had not been studied until early 90s because of technical difficulties. In 1993, we started to embark on this intriguing and challenging issue by mainly scanning force microscopy using monodisperse polystyrene (PS) solid films. Consequently, conclusions obtained thus far are consistently arrived that molecular motion at the PS surfaces is thermally activated in comparison with the corresponding internal bulk region. However, it is far from clear for the moment what the whole picture of such peculiar surface mobility is, although we believe that some parts of it have been successfully clarified to date. Here, experimental methods to examine surface rheological properties, which we have proposed, are mentioned at first, and then, essential points of what we have established are","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"29 2 1","pages":"17-25"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89702763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rheological properties of various colloidal disperse systems were studied in the wide view of linear and non-linear viscoelasticity. The colloidal disperse systems show a unique relaxation mechanism in relatively long-time scale region, which is due to heterogeneity of the system. The disperse systems of fibrous particles show extremely high viscosity and large elastic modulus in comparison with that of the spherical particles.
{"title":"Rheology of Colloidal Disperse Systems","authors":"Takayoshi Matsumoto","doi":"10.1678/RHEOLOGY.32.3","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.32.3","url":null,"abstract":"Rheological properties of various colloidal disperse systems were studied in the wide view of linear and non-linear viscoelasticity. The colloidal disperse systems show a unique relaxation mechanism in relatively long-time scale region, which is due to heterogeneity of the system. The disperse systems of fibrous particles show extremely high viscosity and large elastic modulus in comparison with that of the spherical particles.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"2 1","pages":"3-9"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91239795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mechanical properties of elastomers and their mixtures were investigated with respect to phase transition, that is, strain-induced crystallization of natural rubber. On crystallization of unstretched natural rubber, effect of fatty acids present in the rubber was investigated by polarized light microscopy. The fatty acids were proved to be nucleating agent on the crystallization. The strain-induced crystallization and its effect on the mechanical properties were investigated by measuring tear strength of blend of SBR with natural rubber dispersoid. Despite superposition of tear energy of SBR, the natural rubber/SBR blend showed abrupt increase in tear energy at melting temperature of natural rubber. Since, after removing fatty acids with acetone, the acetone-extracted natural rubber/SBR blend was superposed with temperature shift factor of SBR, fatty acids were suggested to play an important role in not only tear energy but also strain-induced crystallization.
{"title":"Phase Transition and Mechanical Properties of Elastomer","authors":"S. Kawahara","doi":"10.1678/RHEOLOGY.32.259","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.32.259","url":null,"abstract":"Mechanical properties of elastomers and their mixtures were investigated with respect to phase transition, that is, strain-induced crystallization of natural rubber. On crystallization of unstretched natural rubber, effect of fatty acids present in the rubber was investigated by polarized light microscopy. The fatty acids were proved to be nucleating agent on the crystallization. The strain-induced crystallization and its effect on the mechanical properties were investigated by measuring tear strength of blend of SBR with natural rubber dispersoid. Despite superposition of tear energy of SBR, the natural rubber/SBR blend showed abrupt increase in tear energy at melting temperature of natural rubber. Since, after removing fatty acids with acetone, the acetone-extracted natural rubber/SBR blend was superposed with temperature shift factor of SBR, fatty acids were suggested to play an important role in not only tear energy but also strain-induced crystallization.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"72 1","pages":"259-263"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83208218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The role of rheology in food and nutrition science and technology is discussed. Since the mouthfeel or texture is one of the most important attributes of foods, rheological studies have been carried out extensively. Rheology is important in the understanding textural properties of foods and food processing, and mastication and deglutition in eating process. These problems are becoming more important with the advent of aged society where dysphagia is becoming a serious problem. Large deformation and fracture of food gels is discussed. Recent advances in the understanding of sol-gel transition of food macromolecules, sensory evaluation of viscosity in mouth, and flavour release are described.
{"title":"Rheology in Food and Eating","authors":"K. Nishinari","doi":"10.1678/RHEOLOGY.31.41","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.41","url":null,"abstract":"The role of rheology in food and nutrition science and technology is discussed. Since the mouthfeel or texture is one of the most important attributes of foods, rheological studies have been carried out extensively. Rheology is important in the understanding textural properties of foods and food processing, and mastication and deglutition in eating process. These problems are becoming more important with the advent of aged society where dysphagia is becoming a serious problem. Large deformation and fracture of food gels is discussed. Recent advances in the understanding of sol-gel transition of food macromolecules, sensory evaluation of viscosity in mouth, and flavour release are described.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"8 1","pages":"41-50"},"PeriodicalIF":0.0,"publicationDate":"2003-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72767959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Effects of cell destruction on compression moduli of four closed-cell polyethylene were studied by the dynamic viscoelastic measurements in compression mode and the static compression test. In the dynamic viscoelastic measurements, dynamic modulus after cell destruction was smaller than that before cell destruction, and in foams after cell destruction the relations with the dynamic modulus and the initial shrinkage for foams of small elastic modulus was different from those for foams of large elastic modulus. In the static compression test, stress-strain curves of virgin foams gave a bend in the small strain region as observed for expanded polystyrene foams, whereas after cell destruction the stress monotonically increased with strain for foams having low elastic modulus. On the other hand for foams of high elastic modulus, stress-strain curves gave a bend in the small strain region as observed for virgin foams after cell destruction. It is considered that the ratio of the resistance against the pressure inside the cells to the total resistance varies with the elastic modulus of foams.
{"title":"Effects of Cell Destruction on Compression Moduli of Closed-Celled Polyethylene Foams","authors":"H. Adachi, Teruo Hasegawa","doi":"10.1678/RHEOLOGY.31.105","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.105","url":null,"abstract":"Effects of cell destruction on compression moduli of four closed-cell polyethylene were studied by the dynamic viscoelastic measurements in compression mode and the static compression test. In the dynamic viscoelastic measurements, dynamic modulus after cell destruction was smaller than that before cell destruction, and in foams after cell destruction the relations with the dynamic modulus and the initial shrinkage for foams of small elastic modulus was different from those for foams of large elastic modulus. In the static compression test, stress-strain curves of virgin foams gave a bend in the small strain region as observed for expanded polystyrene foams, whereas after cell destruction the stress monotonically increased with strain for foams having low elastic modulus. On the other hand for foams of high elastic modulus, stress-strain curves gave a bend in the small strain region as observed for virgin foams after cell destruction. It is considered that the ratio of the resistance against the pressure inside the cells to the total resistance varies with the elastic modulus of foams.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"24 1","pages":"105-108"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84898743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The relationship between uniaxial elongational viscosity and vacuum molding processability of the PP/PE blends were investigated. Propylene homo-polymer (PP) and 3 kinds of high pressure method low density polyethylene with different molecular weight (PE-A, PE-B, PE-C) were used. Materials were melt blended to the ratio of PP/PE=90/10, 80/20 and 70/30wt% for the experiments. The PP/PE blends showed strain hardening of uniaxial elongational viscosity, while PP showed no strain hardening. The strain hardening of PP/PE increased with increasing of the blend ratio of PE to PP, and the molecular weight of PE. The morphologies of PP/PE under uniaxial elongational flow were observed by TEM. For the samples with the lower molecular weight PE, the larger deformation of PE domain was observed. The deviation of thickness of the vacuum molding products decreased according to the increase of the strain hardening of PP/PE.
{"title":"Study on Uniaxial Elongational Viscosity and Vacuum Molding Processability of the PP/PE Blends","authors":"S. Shiromoto, Taro Miyazawa, K. Koyama","doi":"10.1678/RHEOLOGY.31.321","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.321","url":null,"abstract":"The relationship between uniaxial elongational viscosity and vacuum molding processability of the PP/PE blends were investigated. Propylene homo-polymer (PP) and 3 kinds of high pressure method low density polyethylene with different molecular weight (PE-A, PE-B, PE-C) were used. Materials were melt blended to the ratio of PP/PE=90/10, 80/20 and 70/30wt% for the experiments. The PP/PE blends showed strain hardening of uniaxial elongational viscosity, while PP showed no strain hardening. The strain hardening of PP/PE increased with increasing of the blend ratio of PE to PP, and the molecular weight of PE. The morphologies of PP/PE under uniaxial elongational flow were observed by TEM. For the samples with the lower molecular weight PE, the larger deformation of PE domain was observed. The deviation of thickness of the vacuum molding products decreased according to the increase of the strain hardening of PP/PE.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"62 1","pages":"321-327"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74121159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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