Stress relaxation of entangled ring polymer chains in a linear matrix

2020 ◽  
Vol 64 (6) ◽  
pp. 1315-1324
Author(s):  
Ji-Xuan Hou
Keyword(s):  
Stress Relaxation ◽  
Polymer Chains ◽  
Linear Matrix ◽  
Ring Polymer

scholarly journals Investigation of Ring and Star Polymers in Confined Geometries: Theory and Simulations

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 242
Author(s):  
Joanna Halun ◽  
Pawel Karbowniczek ◽  
Piotr Kuterba ◽  
Zoriana Danel
Keyword(s):  
Star Polymers ◽  
Polymer Chains ◽  
The Other ◽  
Nano Particles ◽  
Dilute Solution ◽  
Confined Geometries ◽  
Density Profiles ◽  
Ideal Ring ◽  
Ring Polymer ◽  
Monomer Density

The calculations of the dimensionless layer monomer density profiles for a dilute solution of phantom ideal ring polymer chains and star polymers with f=4 arms in a Θ-solvent confined in a slit geometry of two parallel walls with repulsive surfaces and for the mixed case of one repulsive and the other inert surface were performed. Furthermore, taking into account the Derjaguin approximation, the dimensionless layer monomer density profiles for phantom ideal ring polymer chains and star polymers immersed in a solution of big colloidal particles with different adsorbing or repelling properties with respect to polymers were calculated. The density-force relation for the above-mentioned cases was analyzed, and the universal amplitude ratio B was obtained. Taking into account the small sphere expansion allowed obtaining the monomer density profiles for a dilute solution of phantom ideal ring polymers immersed in a solution of small spherical particles, or nano-particles of finite size, which are much smaller than the polymer size and the other characteristic mesoscopic length of the system. We performed molecular dynamics simulations of a dilute solution of linear, ring, and star-shaped polymers with N=300, 300 (360), and 1201 (4 × 300 + 1-star polymer with four arms) beads accordingly. The obtained analytical and numerical results for phantom ring and star polymers are compared with the results for linear polymer chains in confined geometries.

Entropic Sampling of Free and Ring Polymer Chains

2005 ◽  
Vol 14 (8) ◽  
pp. 491-504 ◽  
Author(s):  
Nikolai A. Volkov ◽  
Anton A. Yurchenko ◽  
Alexander P. Lyubartsev ◽  
Pavel N. Vorontsov-Velyaminov
Keyword(s):  
Polymer Chains ◽  
Ring Polymer ◽  
Entropic Sampling

Chemical Stress Relaxation of NR Networks Prepared in the Swollen State

1986 ◽  
Vol 59 (4) ◽  
pp. 541-550 ◽  
Author(s):  
Kyung-Do Suh ◽  
Hidetoshi Oikawa ◽  
Kenkichi Murakami
Keyword(s):  
Stress Relaxation ◽  
Network Structure ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Chemical Stress ◽  
Network Chain ◽  
Crosslinking Process ◽  
Dimensional Network ◽  
Chemical Relaxation ◽  
The Difference

Abstract From the experimental results of the present investigation, it is apparent that two kinds of networks which have a different three-dimensional network structure give quite different behavior of chemical stress relaxation, even if both networks have the same network chain density. The difference in three-dimensional network structure for the two kinds of rubber arises from the degree of entanglement, which changes with the concentration of the polymer chains prior to the crosslinking process. The direct cause of chemical relaxation is due to the scission of network chains by degradation, whereas the total relaxation is caused by the change of geometrical conformation of network chains. This then casts doubt on the basic concept of chemorheology which is represented by Equation 2.

Relaxation of Proton Conductivity and Stress in Proton Exchange Membranes Under Strain

2006 ◽  
Vol 128 (4) ◽  
pp. 503-508 ◽  
Author(s):  
Dan Liu ◽  
Michael A. Hickner ◽  
Scott W. Case ◽  
John J. Lesko
Keyword(s):  
Stress Relaxation ◽  
Proton Conductivity ◽  
Proton Exchange Membranes ◽  
Deionized Water ◽  
Proton Exchange ◽  
Polymer Chains ◽  
Water Condition ◽  
Arylene Ether ◽  
Conduction Pathway ◽  
Sulfonated Poly

The stress relaxation and proton conductivity of Nafion 117 membrane (N117-H) and sulfonated poly(arylene ether sulfone) copolymer membrane with 35% sulfonation (BPSH35) in acid forms were investigated under uniaxial loading conditions. The results showed that when the membranes were stretched, their proton conductivities in the direction of the strain initially increased compared to the unstretched films. The absolute increases in proton conductivities were larger at higher temperatures. It was also observed that proton conductivities relaxed exponentially with time at 30°C. In addition, the stress relaxation of N117-H and BPSH35 films under both atmospheric and an immersed (in deionized water) condition was measured. The stresses were found to relax more rapidly than the proton conductivity at the same strains. An explanation for the above phenomena is developed based on speculated changes in the channel connectivity and length of proton conduction pathway in the hydrophilic channels, accompanied by the rotation, reorientation, and disentanglements of the polymer chains in the hydrophobic domains.

Elastic behavior of ring polymer chains

2004 ◽  
Vol 43 (2) ◽  
pp. 223-232 ◽  
Author(s):  
Yu Shen ◽  
Linxi Zhang
Keyword(s):  
Polymer Chains ◽  
Elastic Behavior ◽  
Ring Polymer

Vulcanization. Part IV. The Effects of Compounding Variables on the Nature of Rubber Networks

1964 ◽  
Vol 37 (3) ◽  
pp. 673-678 ◽  
Author(s):  
A. Y. Coran
Keyword(s):  
Stress Relaxation ◽  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Polymer Chains ◽  
Lithium Aluminum ◽  
Sulfur Concentration ◽  
Future Studies ◽  
Network Characteristics ◽  
Hydride Reduction ◽  
Before And After

Abstract It is generally accepted for sulfur vulcanizates of natural rubber that the crosslinks consist of monosulfidic and polysulfidic links between polymer chains. There is indication in the literature that the average number of sulfur atoms per crosslink decreases with an increasing ratio of accelerator concentration to sulfur concentration. Further work was needed and in Paper III of this series a rapid method for determining the relative proportions of monosulfidic and polysulfidic crosslinks was described. The method was based on solvent swelling measurements of thin film vulcanizates before and after a lithium aluminum hydride reduction. By using this method along with a newly developed method for measuring stress-relaxation in a Monsanto Oscillating Disk Rheometer, it is possible to determine the relative proportions of three types of crosslinks: those which are nonreducible, those which are reducible but not rapidly stress-relaxable and those which are reducible and rapidly stress-relaxable. It is assumed that the stress-relaxation is due to cleavage of some of the polysulfidic crosslinks, but not others (those of the type R—S—S—R). It was our purpose here to define network characteristics as a function of compounding variations. The networks were characterized in respect to the distributions of the types of crosslinks as well as the number of crosslinks. It is felt that the nature of the networks as measured on the microscale would be significantly reflected in gross properties; this should be borne out in future studies.

scholarly journals Compression and Stretching of Confined Linear and Ring Polymers by Applying Force

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4193
Author(s):  
Wenduo Chen ◽  
Xiangxin Kong ◽  
Qianqian Wei ◽  
Huaiyu Chen ◽  
Jiayin Liu ◽  
...  
Keyword(s):  
Polymer Chains ◽  
Compression Process ◽  
Confined Polymers ◽  
Buckling Instability ◽  
Critical Buckling Force ◽  
Ring Polymers ◽  
Ring Polymer ◽  
Folded Structures ◽  
Two Sides ◽  
Strong Confinement

We use Langevin dynamics to study the deformations of linear and ring polymers in different confinements by applying compression and stretching forces on their two sides. Our results show that the compression deformations are the results of an interplay among of polymer rigidity, degree of confinement, and force applied. When the applied force is beyond the threshold required for the buckling transition, the semiflexible chain under the strong confinement firstly buckles; then comes helical deformation. However, under the same force loading, the semiflexible chain under the weaker confinement exhibits buckling instability and shrinks from the folded ends/sides until it becomes three-folded structures. This happens because the strong confinement not only strongly reduces the buckling wavelength, but also increases the critical buckling force threshold. For the weakly confined polymers, in compression process, the flexible linear polymer collapses into condensed states under a small external force, whereas the ring polymer only shows slight shrinkage, due to the excluded volume interactions of two strands in the crowded states. These results are essential for understanding the deformations of the ring biomacromolecules and polymer chains in mechanical compression or driven transport.

The Thermal and Oxidative Stability of Chlorosulfonated Polyethylene Vulcanizates as Measured by Stress Relaxation

1971 ◽  
Vol 44 (5) ◽  
pp. 1410-1420
Author(s):  
F. Haaf ◽  
P. R. Johnson
Keyword(s):  
Stress Relaxation ◽  
Elevated Temperatures ◽  
Oxidative Degradation ◽  
Activation Energies ◽  
Polymer Chains ◽  
Chlorosulfonated Polyethylene ◽  
Thermal And Oxidative Stability ◽  
Relaxation Measurements ◽  
Accelerator System ◽  
Interchange Reactions

Abstract Stress relaxation measurements of chlorosulfonated polyethylene vulcanizates show that curing with m-phenylene-bis-maleimide gives thermally more stable crosslinks than the conventional metal oxide/sulfur accelerator system. The superior thermal stability of the bis-maleimide cure is based on the covalent nature of the crosslinks. In conventionally cured vulcanizates interchange reactions of the metal sulfonate and polysulfide crosslinks occur at elevated temperatures. The interchange reactions of the crosslinks cause a rapid stress decline at the beginning of the stress relaxation process. Over longer aging periods stress relaxation due to oxidative degradation becomes apparent in vulcanizates of both types. The activation energies of oxidative stress relaxations are very similar for the bis-maleimide and the conventional cure. The similarity of the activation energies indicates that oxidative degradation follows the same path. The site of the oxidative attack is established for bis-maleimide cured vulcanizates. Oxidative degradation is found to occur in the polymer chains rather than in the crosslinks. The effects of fillers and stabilizers are investigated and their mode of action is explained on the basis of the stress relaxation results.

On the theory of stress relaxation by cross-link reorganization

1973 ◽  
Vol 335 (1602) ◽  
pp. 289-300 ◽  
Keyword(s):  
Stress Relaxation ◽  
Elasticity Theory ◽  
Present Author ◽  
Polymer Chains ◽  
Elasticity Problem ◽  
Cross Link ◽  
Dynamical Calculation ◽  
Cross Links ◽  
Points Of View ◽  
Comparison With Experiments

Stress relaxation by scission and reformation of cross-links in a network of interpenetrable Gaussian polymer chains is discussed theoretically from two points of view. First, a model due to Flory, based on the intuitive use of results for a different elasticity problem, is reconsidered in the light of a new analysis of that problem by the present author, using Edwards’s elasticity theory in place of the ‘classical’ methods of Flory and others. The stress σ predicted by Flory’s model is found to be quite sensitive to which elasticity theory is used, but a comparison with experiments by Thomas is inconclusive. Secondly, the asymptotic relaxation is determined by a more reliable dynamical calculation. This predicts σα t -½, a slower decay than that given by Flory’s model (whichever elasticity theory is used), and demontrates the failure of that model at large times.

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