scholarly journals Stress Relaxation of Polymer Solutions under Large Strain: Application of Double-Step Strain

1974 ◽  
Vol 5 (3) ◽  
pp. 283-287 ◽  
Author(s):  
Kunihiro Osaki ◽  
Yoshiyuki Einaga ◽  
Michio Kurata ◽  
Nobuhiro Yamada ◽  
Mikio Tamura
Keyword(s):  
Stress Relaxation ◽  
Polymer Solutions ◽  
Large Strain ◽  
Double Step ◽  
Step Strain

scholarly journals Stress Relaxation of Polymer Solutions under Large Strain

1971 ◽  
Vol 2 (4) ◽  
pp. 550-552 ◽  
Author(s):  
Yoshiyuki Einaga ◽  
Kunihiro Osaki ◽  
Michio Kurata ◽  
Shin-ichi Kimura ◽  
Mikio Tamura
Keyword(s):  
Stress Relaxation ◽  
Polymer Solutions ◽  
Large Strain

scholarly journals Stress Relaxation of Polymer Solutions under Large Strain

1973 ◽  
Vol 5 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Yoshiyuki Einaga ◽  
Kunihiro Osaki ◽  
Michio Kurata ◽  
Shin-ichi Kimura ◽  
Nobuhiro Yamada ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Polymer Solutions ◽  
Large Strain

scholarly journals Capturing the Transient Microstructure of a Physically Assembled Gel Subjected to Temperature and Large Deformation

2021 ◽  
Author(s):  
Rosa Maria Badani Prado ◽  
Satish Mishra ◽  
Wesley R. Burghardt ◽  
Santanu Kundu
Keyword(s):  
Stress Relaxation ◽  
Relaxation Process ◽  
Triblock Copolymer ◽  
Large Strain ◽  
Real Life ◽  
Exponential Model ◽  
Complex Nature ◽  
Gelation Process ◽  
Oriented Structure ◽  
Step Strain

The microstructure of physically assembled gels depends on mechanical loading and environmental stimuli such as temperature. Here, we report the real-time change in the structure of physically assembled triblock copolymer gels that consist of 10 wt% and 20 wt% of poly(styrene)-poly(isoprene)-poly(styrene) [PS-PI-PS] triblock copolymer in mineral oil (i) during the gelation process with decreasing temperature, (ii) subjected to large oscillatory deformation, and (iii) during the stress-relaxation process after the application of a step-strain. The presence of loosely bounded PS-aggregates at temperatures higher than the rheometrically determined gelation temperature (Tgel) captures the progressive gelation process spanning over a broad temperature range. However, the microstructure fully develops at temperatures suciently lower than Tgel, and the storage modulus (G0 ) also reaches a plateau at those temperatures. The microstructure orients in the stretching direction with the applied strain. In an oscillation strain cycle, such oriented structure has been observed at low-strain. But, at large-strain, the oriented structure splits, and only a fraction of midblock participates in load-bearing. This has been attributed to the endblock pullout from the aggregates, likely caused by the strain localization in the samples. Both microstructure recovery and time-dependent moduli during the stress-relaxation process after the application of a step-strain can be captured using a stretched-exponential model. However, the microstructure recovery time has been found to be two orders of magnitude slower than the stress-relaxation time at room temperature, indicating a complex nature of relaxation process involving midblock relaxation, endblock pullout and reassociation process. Due to their viscoelastic nature, these gels' mechanical responses are sensitive to strain, temperature, and rate of deformation. Therefore, insights into the microstructural information as a function of these parameters will assist these gels' real-life applications and design new gels with improved properties<br>

scholarly journals Capturing the Transient Microstructure of a Physically Assembled Gel Subjected to Temperature and Large Deformation

2021 ◽  
Author(s):  
Rosa Maria Badani Prado ◽  
Satish Mishra ◽  
Humayun Ahmad ◽  
Wesley R. Burghardt ◽  
Santanu Kundu
Keyword(s):  
Stress Relaxation ◽  
Relaxation Process ◽  
Triblock Copolymer ◽  
Large Strain ◽  
Real Life ◽  
Exponential Model ◽  
Complex Nature ◽  
Gelation Process ◽  
Oriented Structure ◽  
Step Strain

The microstructure of physically assembled gels depends on mechanical loading and environmental stimuli such as temperature. Here, we report the real-time change in the structure of physically assembled triblock copolymer gels that consist of 10 wt% and 20 wt% of poly(styrene)-poly(isoprene)-poly(styrene) [PS-PI-PS] triblock copolymer in mineral oil (i) during the gelation process with decreasing temperature, (ii) subjected to large oscillatory deformation, and (iii) during the stress-relaxation process after the application of a step-strain. The presence of loosely bounded PS-aggregates at temperatures higher than the rheologically determined gelation temperature (Tgel) captures the progressive gelation process spanning over a broad temperature range. However, the microstructure fully develops at temperatures sufficiently lower than Tgel. The microstructure orients in the stretching direction with the applied strain. In an oscillation strain cycle, such oriented structure has been observed at low-strain. But, at large-strain, because of strain-localization the oriented structure splits, and only a fraction of midblock participates in load-bearing. Both microstructure recovery and time-dependent moduli during the stress-relaxation process after the application of a step-strain have been captured using a stretched-exponential model. However, the microstructure recovery time has been found to be two orders of magnitude slower than the stress-relaxation time at room temperature, indicating a complex nature of stress-relaxation and microstructure recovery processes involving midblock relaxation, endblock pullout and reassociation. Due to their viscoelastic nature, these gels' mechanical responses are sensitive to strain, temperature, and rate of deformation. Therefore, insights into the microstructural information as a function of these parameters will assist these gels' real-life applications and design new gels with improved properties.

scholarly journals Capturing the Transient Microstructure of a Physically Assembled Gel Subjected to Temperature and Large Deformation

2021 ◽  
Author(s):  
Rosa Maria Badani Prado ◽  
Satish Mishra ◽  
Wesley R. Burghardt ◽  
Santanu Kundu
Keyword(s):  
Stress Relaxation ◽  
Relaxation Process ◽  
Triblock Copolymer ◽  
Large Strain ◽  
Real Life ◽  
Exponential Model ◽  
Complex Nature ◽  
Gelation Process ◽  
Oriented Structure ◽  
Step Strain

The microstructure of physically assembled gels depends on mechanical loading and environmental stimuli such as temperature. Here, we report the real-time change in the structure of physically assembled triblock copolymer gels that consist of 10 wt% and 20 wt% of poly(styrene)-poly(isoprene)-poly(styrene) [PS-PI-PS] triblock copolymer in mineral oil (i) during the gelation process with decreasing temperature, (ii) subjected to large oscillatory deformation, and (iii) during the stress-relaxation process after the application of a step-strain. The presence of loosely bounded PS-aggregates at temperatures higher than the rheometrically determined gelation temperature (Tgel) captures the progressive gelation process spanning over a broad temperature range. However, the microstructure fully develops at temperatures suciently lower than Tgel, and the storage modulus (G0 ) also reaches a plateau at those temperatures. The microstructure orients in the stretching direction with the applied strain. In an oscillation strain cycle, such oriented structure has been observed at low-strain. But, at large-strain, the oriented structure splits, and only a fraction of midblock participates in load-bearing. This has been attributed to the endblock pullout from the aggregates, likely caused by the strain localization in the samples. Both microstructure recovery and time-dependent moduli during the stress-relaxation process after the application of a step-strain can be captured using a stretched-exponential model. However, the microstructure recovery time has been found to be two orders of magnitude slower than the stress-relaxation time at room temperature, indicating a complex nature of relaxation process involving midblock relaxation, endblock pullout and reassociation process. Due to their viscoelastic nature, these gels' mechanical responses are sensitive to strain, temperature, and rate of deformation. Therefore, insights into the microstructural information as a function of these parameters will assist these gels' real-life applications and design new gels with improved properties<br>

Normal stress relaxation in reversing double‐step strain flowsa)

1994 ◽  
Vol 38 (5) ◽  
pp. 1297-1315 ◽  
Author(s):  
D. C. Venerus ◽  
H. Kahvand
Keyword(s):  
Stress Relaxation ◽  
Normal Stress ◽  
Double Step ◽  
Step Strain

STRESS RELAXATION OF MAGNETORHEOLOGICAL FLUIDS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2655-2661
Author(s):  
W. H. LI ◽  
G. CHEN ◽  
S. H. YEO ◽  
H. DU
Keyword(s):  
Stress Relaxation ◽  
Viscoelastic Model ◽  
Relaxation Modulus ◽  
Damping Function ◽  
Mr Fluids ◽  
Large Step ◽  
Linear Viscoelastic ◽  
Predicted Values ◽  
Two Parameters ◽  
Step Strain

In this paper, the experimental and modeling study and analysis of the stress relaxation characteristics of magnetorheological (MR) fluids under step shear are presented. The experiments are carried out using a rheometer with parallel-plate geometry. The applied strain varies from 0.01% to 100%, covering both the pre-yield and post-yield regimes. The effects of step strain, field strength, and temperature on the stress modulus are addressed. For small step strain ranges, the stress relaxation modulus G(t,γ) is independent of step strain, where MR fluids behave as linear viscoelastic solids. For large step strain ranges, the stress relaxation modulus decreases gradually with increasing step strain. Morever, the stress relaxation modulus G(t,γ) was found to obey time-strain factorability. That is, G(t,γ) can be represented as the product of a linear stress relaxation G(t) and a strain-dependent damping function h(γ). The linear stress relaxation modulus is represented as a three-parameter solid viscoelastic model, and the damping function h(γ) has a sigmoidal form with two parameters. The comparison between the experimental results and the model-predicted values indicates that this model can accurately describe the relaxation behavior of MR fluids under step strains.

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