Characterization of Polymers under Large Deformation. I. Repeated Chemical Stress Relaxation of Vulcanized Rubbers

1973 ◽  
Vol 46 (2) ◽  
pp. 388-397
Author(s):  
Takae Kusano ◽  
Kenkichi Murakami
Keyword(s):  
Stress Relaxation ◽  
Large Deformation ◽  
Mechanical Stimulus ◽  
Relaxation Behavior ◽  
Chemical Stress ◽  
Measurement Temperature ◽  
Extension Ratio ◽  
Relaxation Measurements ◽  
Relaxation Curves

Abstract In this investigation, repeated chemical stress relaxation measurements were carried out to observe the relaxation behavior at large deformation. It was found that the repeated chemical stress relaxation curves were affected by both measurement temperature and the extension ratio of rubber. It was suggested on the basis of the results that temperature and mechanical stimulus have a similar effect on the stress relaxation curves.

scholarly journals Mechanical Characterization of Spray-Dried Granules by Compression and Stress-Relaxation Technique. Analysis of Relaxation Behavior.

1999 ◽  
Vol 107 (1252) ◽  
pp. 1183-1187 ◽  
Author(s):  
JunIchiro TSUBAKI ◽  
Takamasa MORI ◽  
Toshiyuki KONISHI ◽  
Akihisa TSURUTA ◽  
Hidetoshi MORI ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Mechanical Characterization ◽  
Relaxation Behavior ◽  
Relaxation Technique ◽  
Spray Dried ◽  
Technique Analysis

Studies of Viscoelastic Relaxation of Some Nitrile Rubbers under Compressive Stress

1977 ◽  
Vol 50 (5) ◽  
pp. 906-914 ◽  
Author(s):  
B. Stenberg ◽  
J. F. Jansson
Keyword(s):  
Stress Relaxation ◽  
Point Of View ◽  
Relaxation Behavior ◽  
Relaxation Processes ◽  
Theoretical Point ◽  
Stress Relaxation Behavior ◽  
Physical Mechanisms ◽  
Viscoelastic Stress Relaxation ◽  
Nitrile Rubbers ◽  
Relaxation Curves

Abstract Stress relaxation in rubbers is usually supposed to be due to chemical aging phenomena of a mainly elastic material. Considerable physical viscoelastic processes can, however, be observed in the rubbery region, depending upon the type of rubber, crosslink density, type of crosslink, filler, and so on. Thus, in chemical stress relaxation experiments chemical and physical mechanisms are superimposed and can seldom be distinguished. Stress relaxation curves registered at different temperatures contain contributions from both types of mechanism. From a practical, as well as a theoretical, point of view it is therefore essential to find methods of distinguishing between the two relaxation processes. This would be possible if the relaxation curves were obtained during periods of time so short that the chemical relaxation can be neglected. The long-term physical relaxation is then obtained by shifting the curves by, for instance, the method of reduced variables. This technique has been utilized by Curro and Salazar. We now present an alternative procedure by which the physical viscoelastic stress relaxation behavior is determined from dynamic data. The physical relaxation curves are calculated from values of E′(ω) and E″(ω) obtained at different frequencies and temperatures. In this method of determining the physical relaxation, no change of sample is needed, nor is it necessary to allow the sample to relax between measurements. The stress relaxation behavior under compression of three nitrile rubbers has been studied, and it is shown that physical mechanisms dominate just above room temperature, while chemical mechanisms dominate at higher temperatures.

Viscoelastic Characterization of an Epoxy-Based Molding Compound

1995 ◽  
Vol 390 ◽  
Author(s):  
V. H. Kenner ◽  
M. R. Julian ◽  
C. H. Popelar ◽  
M. K. Chengalva
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Viscoelastic Behavior ◽  
Tensile Tests ◽  
Prony Series ◽  
Master Curves ◽  
Molding Compound ◽  
Relaxation Curves

ABSTRACTThis paper describes the viscoelastic characterization of a highly filled epoxy molding compound commonly used in electronic packaging applications. Both stress relaxation tests and constant strain rate tensile tests were conducted. The material was found to be nonlinear in its viscoelastic behavior and to be amenable to horizontal shifting to form master curves. A representation of the master stress relaxation curves in terms of a Prony series is given, and the use of this representation illustrated in the context of both linear and nonlinear representations of the viscoelastic behavior to predict the results of the constant strain rate experiments.

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