Focusing on the particle size of gellan gum microgel fluid dispersion, we found that even with the same composition, the appearance and rheological characteristics of microgel fluid dispersion were different depending on the difference of particle size. Comparison among rheological characteristics indicated that the greater the particle size of microgel was, the larger the yield stress and shear stress during flowage were and that there was an appropriate correlation (r=0.97) between the particle size of microgel and the yield stress of fluid dispersion. It was observed that among microgel fluid dispersion samples having the same particle size, the less concentration of calcium ions added as crosslinker for double helix they had, the greater shear stress they showed. We considered it as an influence of interaction among microgel particles. We found that the control of the particle size of microgel fluid dispersion and the calcium ion concentration was effective as a method of controlling the properties of microgel fluid dispersion. Microgel particles with smaller size decrease the yield stress of fluid dispersion, deteriorating the dispersion stability of dispersoid. However, by including the dispersoid in microgel particles, we could prepare a product providing a compatibility between the product appearance and stability.
{"title":"Effect of the Particle Size on the Rheology of Gellan Gum Micro Gel","authors":"Riwako Nakamoto, Ryoji Yasue","doi":"10.1678/RHEOLOGY.31.337","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.337","url":null,"abstract":"Focusing on the particle size of gellan gum microgel fluid dispersion, we found that even with the same composition, the appearance and rheological characteristics of microgel fluid dispersion were different depending on the difference of particle size. Comparison among rheological characteristics indicated that the greater the particle size of microgel was, the larger the yield stress and shear stress during flowage were and that there was an appropriate correlation (r=0.97) between the particle size of microgel and the yield stress of fluid dispersion. It was observed that among microgel fluid dispersion samples having the same particle size, the less concentration of calcium ions added as crosslinker for double helix they had, the greater shear stress they showed. We considered it as an influence of interaction among microgel particles. We found that the control of the particle size of microgel fluid dispersion and the calcium ion concentration was effective as a method of controlling the properties of microgel fluid dispersion. Microgel particles with smaller size decrease the yield stress of fluid dispersion, deteriorating the dispersion stability of dispersoid. However, by including the dispersoid in microgel particles, we could prepare a product providing a compatibility between the product appearance and stability.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"10 1","pages":"337-342"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84309299","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}
Prominent viscoelasticity emerges in entangled polymeric liquids composed of long, flexible polymer chains exhibiting active thermal motion. In attempt of establishing a molecular picture of the entanglement dynamics, extensive theoretical and experimental efforts have been made over several decades. This article summarizes the current picture of the equilibrium dynamics of the entangled chains and addresses some remaining problems.
{"title":"Rheology of entangled polymeric liquids: Current molecular pictures and problems","authors":"H. Watanabe","doi":"10.1678/RHEOLOGY.31.3","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.3","url":null,"abstract":"Prominent viscoelasticity emerges in entangled polymeric liquids composed of long, flexible polymer chains exhibiting active thermal motion. In attempt of establishing a molecular picture of the entanglement dynamics, extensive theoretical and experimental efforts have been made over several decades. This article summarizes the current picture of the equilibrium dynamics of the entangled chains and addresses some remaining problems.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"18 1","pages":"3-14"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85581443","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}
Particles dispersed in a liquid tend to form flocs due to attractive forces between particles. The rheological properties of suspensions depend on the dynamic structures of flocs in shear fields. Main task of suspension rheology is to establish the quantitative relation among the mechanical properties of particle bond, geometrical structures of flocs, and macroscopic rheology. For understanding of current status of suspension rheology, the fundamental properties of ordinary flocculated suspensions are summarized. The most important aspect is that the particle bonds are not broken down in a quiescent state. Hence, the gross structure of flocs may be statistically invariant. The relation between rheology and floc structure is discussed on the basis of fractal and percolation concepts. The suspensions flocculated by polymers show interesting rheological behavior. For example, the suspensions flocculated by reversible bridging are Newtonian at low shear rates and shear-thickening at high shear rates, whereas the ordinary flocculated suspensions are shear-thinning in a wide range of shear rates due to the progressive breakdown of flocs. Since the particle-particle interactions are strongly influenced by adsorption affinity for surfaces, the flocculation induced by polymer has great potential as a new technique in rheology control of suspensions. The unique rheological behavior can be directly connected with the mechanical properties of the bonds between two primary particles. The physical quantities which determine the floc structures and rheological properties are the transverse and central components of attractive force between particles. The importance of vector nature of particle bonds is demonstrated, with a perspective of quantitative understanding of suspension rheology.
{"title":"The Present Status and Prospect of Suspension Rheology.","authors":"Y. Otsubo","doi":"10.1678/RHEOLOGY.31.15","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.15","url":null,"abstract":"Particles dispersed in a liquid tend to form flocs due to attractive forces between particles. The rheological properties of suspensions depend on the dynamic structures of flocs in shear fields. Main task of suspension rheology is to establish the quantitative relation among the mechanical properties of particle bond, geometrical structures of flocs, and macroscopic rheology. For understanding of current status of suspension rheology, the fundamental properties of ordinary flocculated suspensions are summarized. The most important aspect is that the particle bonds are not broken down in a quiescent state. Hence, the gross structure of flocs may be statistically invariant. The relation between rheology and floc structure is discussed on the basis of fractal and percolation concepts. The suspensions flocculated by polymers show interesting rheological behavior. For example, the suspensions flocculated by reversible bridging are Newtonian at low shear rates and shear-thickening at high shear rates, whereas the ordinary flocculated suspensions are shear-thinning in a wide range of shear rates due to the progressive breakdown of flocs. Since the particle-particle interactions are strongly influenced by adsorption affinity for surfaces, the flocculation induced by polymer has great potential as a new technique in rheology control of suspensions. The unique rheological behavior can be directly connected with the mechanical properties of the bonds between two primary particles. The physical quantities which determine the floc structures and rheological properties are the transverse and central components of attractive force between particles. The importance of vector nature of particle bonds is demonstrated, with a perspective of quantitative understanding of suspension rheology.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"27 1","pages":"15-22"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77296529","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 and mechanical properties and particle dispersion state of silicone resin filled with various silica particles were investigated before and after crosslinking. Uncrosslinked resin filled with smaller particles at higher content showed higher storage modulus G' and complex viscosity |η*| at lower frequency region and a second plateau was observed. When the particle size is almost identical, particle with hydrophilic surface made G' and |η*| slightly higher. From those results, liquid matrix containing smaller particles at higher content has stronger three-dimensional structure. This structure seems to be stronger in the hydrophobic matrix filled in the hydrophilic particles. On the other hand, small hydrophobic particles increased the storage modulus E' of crosslinked resin at the rubbery region. These increases in E' at the rubbery region reflect the increases in the tensile modulus and strength of particle filled elastomers in the tensile test. These results suggested that the three-dimensional network structure formed with hydrophilic particles in hydrophobic matrix increased elastic character when the matrix is uncrosslinked. However, once matrix is crosslinked, adhesion between particles and matrix enhances the mechanical properties.
{"title":"Rheological and Mechanical Properties of Particle Filled Elastomers","authors":"Kazuyuki Shohara, K. Uotani, H. Yamane","doi":"10.1678/RHEOLOGY.31.329","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.329","url":null,"abstract":"Rheological and mechanical properties and particle dispersion state of silicone resin filled with various silica particles were investigated before and after crosslinking. Uncrosslinked resin filled with smaller particles at higher content showed higher storage modulus G' and complex viscosity |η*| at lower frequency region and a second plateau was observed. When the particle size is almost identical, particle with hydrophilic surface made G' and |η*| slightly higher. From those results, liquid matrix containing smaller particles at higher content has stronger three-dimensional structure. This structure seems to be stronger in the hydrophobic matrix filled in the hydrophilic particles. On the other hand, small hydrophobic particles increased the storage modulus E' of crosslinked resin at the rubbery region. These increases in E' at the rubbery region reflect the increases in the tensile modulus and strength of particle filled elastomers in the tensile test. These results suggested that the three-dimensional network structure formed with hydrophilic particles in hydrophobic matrix increased elastic character when the matrix is uncrosslinked. However, once matrix is crosslinked, adhesion between particles and matrix enhances the mechanical properties.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"18 1","pages":"329-335"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74436010","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}
Two dimensional jets of a visocoelastic fluid have been studied using aqueous surfactant solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal). The solution shows strong viscoelasticity even at low concentration condition 0.01[mol/l] and 0.07[mol/l] for CTAB and NaSal, respectively. Shapes of jets issuing from slits are observed, and the birefringence of sample solution is measured along the flow direction from the inside to the outside of the slit. Elastic stresses of jets are evaluated from their shapes, and the degree of orientation of thread-like micelles is calculated from the value of birefringence. The elastic stress of the slit jets agrees with that of capillary jets, and the value of birefringence increases and is followed by decreasing inside of the slit near the exit. The increase and decrease in the value of birefringence is related to a change in the orientation of micelles caused by the contraction and expansion of the flow near the exit. The increase in the value of birefringence is also observed with die swelling.
{"title":"Birefringence of Aqueous Surfactant Solution in the Vicinity of a Slit Exit","authors":"Hideo Asama, T. Hasegawa, T. Narumi","doi":"10.1678/RHEOLOGY.31.99","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.99","url":null,"abstract":"Two dimensional jets of a visocoelastic fluid have been studied using aqueous surfactant solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal). The solution shows strong viscoelasticity even at low concentration condition 0.01[mol/l] and 0.07[mol/l] for CTAB and NaSal, respectively. Shapes of jets issuing from slits are observed, and the birefringence of sample solution is measured along the flow direction from the inside to the outside of the slit. Elastic stresses of jets are evaluated from their shapes, and the degree of orientation of thread-like micelles is calculated from the value of birefringence. The elastic stress of the slit jets agrees with that of capillary jets, and the value of birefringence increases and is followed by decreasing inside of the slit near the exit. The increase and decrease in the value of birefringence is related to a change in the orientation of micelles caused by the contraction and expansion of the flow near the exit. The increase in the value of birefringence is also observed with die swelling.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"9 1","pages":"99-104"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87946842","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}
For evaluation of thermal endurance in foamed plastics, temperature and time characteristics of compression dynamic modulus of four expanded polystyrene foams were investigated by the dynamic viscoelastic measurements in compression mode. Log t which dynamic modulus 10 or 20% fall as compared with the start time of measurement, has been found to relate linearly with the reciprocal of the absolute temperature from the time characteristics of dynamic modulus in foams before destruction of cell. Thermal endurance temperature that is a measure to evaluate thermal endurance is not suitable for being given by the temperature characteristics of the dynamic modulus, and is suitable for being given by the temperature for setting up durable time from the relations between log t and the reciprocal of the absolute temperature.
{"title":"Evaluation of Thermal Endurance Characteristics of Expanded Polystyrene Foams by Dynamic Compression Modulus","authors":"H. Adachi, Teruo Hasegawa","doi":"10.1678/RHEOLOGY.31.109","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.31.109","url":null,"abstract":"For evaluation of thermal endurance in foamed plastics, temperature and time characteristics of compression dynamic modulus of four expanded polystyrene foams were investigated by the dynamic viscoelastic measurements in compression mode. Log t which dynamic modulus 10 or 20% fall as compared with the start time of measurement, has been found to relate linearly with the reciprocal of the absolute temperature from the time characteristics of dynamic modulus in foams before destruction of cell. Thermal endurance temperature that is a measure to evaluate thermal endurance is not suitable for being given by the temperature characteristics of the dynamic modulus, and is suitable for being given by the temperature for setting up durable time from the relations between log t and the reciprocal of the absolute temperature.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"160 12 1","pages":"109-114"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83263163","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 in steady planar elongational flow of CTAB/NaSal aqueous solutions were investigated using a 4-roll mill flow cell. The planar elongational stress was measured by using a flow-birefringence technique, which is based on the stress-optic rule. On the other hand, the rate of planar elongation was accurately determined by the analysis of the tracer particles in the system. The planar elongational viscosity showed elongational thinning as well as shear thinning. The planar elongational viscosity measured in the 4-roll mill flow cell was compared with that measured in a squeeze flow cell, and both well agreed with each other. Trouton ratio was evaluated to be 4 in both the Newtonian and elongational thinning region. Flow instability is observed in the 4-roll mill flow cell at a planar elongation rate lower than the shear rate at which the shear flow instability takes place.
{"title":"Steady Planar Elongational Viscosity of CTAB/NaSal Aqueous Solutions Measured in a 4-Roll Mill Flow Cell.","authors":"Manabu Kato, Tsutomu Takahashi, M. Shirakashi","doi":"10.1678/RHEOLOGY.30.283","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.30.283","url":null,"abstract":"Rheological properties in steady planar elongational flow of CTAB/NaSal aqueous solutions were investigated using a 4-roll mill flow cell. The planar elongational stress was measured by using a flow-birefringence technique, which is based on the stress-optic rule. On the other hand, the rate of planar elongation was accurately determined by the analysis of the tracer particles in the system. The planar elongational viscosity showed elongational thinning as well as shear thinning. The planar elongational viscosity measured in the 4-roll mill flow cell was compared with that measured in a squeeze flow cell, and both well agreed with each other. Trouton ratio was evaluated to be 4 in both the Newtonian and elongational thinning region. Flow instability is observed in the 4-roll mill flow cell at a planar elongation rate lower than the shear rate at which the shear flow instability takes place.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"67 1","pages":"283-287"},"PeriodicalIF":0.0,"publicationDate":"2002-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81600778","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}
We observed collision and coalescence after application of large step shear strains for two polyisobutylene (PIB) droplets in polydimethylsiloxane (PDMS) matrix using a stereo microscope. When coalescence occurred, interface vanished in an overlapped area of deformed droplets. Then a single droplet recovered to spherical shape. Time necessary for recovery to spherical shape with coalescence was longer than that without coalescence. Coalescence was easy to occur for larger strain and smaller d0/r 0, where d0 and r0 represent initial distance between centers of droplets and initial droplet radius, respectively. In the case of shape recovery without coalescence, the distance between the centers after shape recovery was smaller than d0. Time dependence of shape of droplets was similar in both cases with coalescence and without coalescence. Ratio of length of overlap, lov', to length of semi major axis, a', in view perpendicular to shear plane determines occurrence of coalescence.
{"title":"Observation of Coalescence of Two Polyisobutylene Droplets in Polydimethylsiloxane under Large Step Shear Strain","authors":"Kenzo Okamoto, Ryota Tamura, M. Ishikawa","doi":"10.1678/RHEOLOGY.30.45","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.30.45","url":null,"abstract":"We observed collision and coalescence after application of large step shear strains for two polyisobutylene (PIB) droplets in polydimethylsiloxane (PDMS) matrix using a stereo microscope. When coalescence occurred, interface vanished in an overlapped area of deformed droplets. Then a single droplet recovered to spherical shape. Time necessary for recovery to spherical shape with coalescence was longer than that without coalescence. Coalescence was easy to occur for larger strain and smaller d0/r 0, where d0 and r0 represent initial distance between centers of droplets and initial droplet radius, respectively. In the case of shape recovery without coalescence, the distance between the centers after shape recovery was smaller than d0. Time dependence of shape of droplets was similar in both cases with coalescence and without coalescence. Ratio of length of overlap, lov', to length of semi major axis, a', in view perpendicular to shear plane determines occurrence of coalescence.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"61 5 1","pages":"45-48"},"PeriodicalIF":0.0,"publicationDate":"2002-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86800983","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}
One-dimensional flow model for non-Newtonian fluids in a dual cavity slot die is presented. The viscosity of nonNewtonian fluids is treated as the Ellis model. The conservation equations of mass and momentum in a dual-cavity slot die are one-dimensionally simplified by assuming an appropriate mean flow over the cross section of the flow. The flow field in the slot is assumed to be fully developed. The equations of flow for the cavity and the slot are derived separately and then coupled. We use a finite difference method to solve these governing equations. Using this model, we find that the location and the cross-section area of a secondary cavity have large effects on the distribution of outlet flow. It is concluded that the dual cavity die can effectively reduce the flow non-uniformity.
{"title":"Study of the Flow in a Dual Cavity Slot Die.","authors":"T. Tsuda, T. Hasegawa, T. Narumi","doi":"10.1678/RHEOLOGY.30.179","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.30.179","url":null,"abstract":"One-dimensional flow model for non-Newtonian fluids in a dual cavity slot die is presented. The viscosity of nonNewtonian fluids is treated as the Ellis model. The conservation equations of mass and momentum in a dual-cavity slot die are one-dimensionally simplified by assuming an appropriate mean flow over the cross section of the flow. The flow field in the slot is assumed to be fully developed. The equations of flow for the cavity and the slot are derived separately and then coupled. We use a finite difference method to solve these governing equations. Using this model, we find that the location and the cross-section area of a secondary cavity have large effects on the distribution of outlet flow. It is concluded that the dual cavity die can effectively reduce the flow non-uniformity.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"69 1","pages":"179-185"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84307867","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}
Dynamic viscoelastic properties, steady shear and biaxial extensional flow behaviors have been investigated for melts of potassium titanate whisker filled polyoxymethylene. A second plateau appears in the low frequency region of the storage modulus G', and the plateau value increases with whisker content. Addition of the whisker also increases the steady shear viscosity and the low strain rate asymptote of the biaxial extensional viscosity. The upturn of biaxial extensional viscosity from the low strain rate asymptote decreases by the addition of whisker due to suppression of polymer chain extension. Change in whisker dispersion and orientation in the melts was observed with scanning electron microscopy after quenching the samples in biaxial extensional flow. The degree of whisker orientation to the flow direction decreases with increasing strain rate in the range where the strain rate is much greater than the rate of whisker orientation and it is smaller than or comparable with the relaxation rate of the matrix chain. It is suggested that the matrix does not have enough power to orient the whisker in this range of strain rate.
{"title":"Rheological Properties and Fiber Dispersion and Orientation in Potassium Titanate Whisker Filled Polyoxymethylene Melts.","authors":"Wanhu Zhang, H. Yamane, Masaoki Takahashi","doi":"10.1678/RHEOLOGY.30.33","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.30.33","url":null,"abstract":"Dynamic viscoelastic properties, steady shear and biaxial extensional flow behaviors have been investigated for melts of potassium titanate whisker filled polyoxymethylene. A second plateau appears in the low frequency region of the storage modulus G', and the plateau value increases with whisker content. Addition of the whisker also increases the steady shear viscosity and the low strain rate asymptote of the biaxial extensional viscosity. The upturn of biaxial extensional viscosity from the low strain rate asymptote decreases by the addition of whisker due to suppression of polymer chain extension. Change in whisker dispersion and orientation in the melts was observed with scanning electron microscopy after quenching the samples in biaxial extensional flow. The degree of whisker orientation to the flow direction decreases with increasing strain rate in the range where the strain rate is much greater than the rate of whisker orientation and it is smaller than or comparable with the relaxation rate of the matrix chain. It is suggested that the matrix does not have enough power to orient the whisker in this range of strain rate.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":"6 1","pages":"33-40"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86726096","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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