Probing the early stages of tablet disintegration by stress relaxation measurement

2018 ◽  
Vol 124 ◽  
pp. 145-152 ◽  
Author(s):  
Jan Tomas ◽  
Marek Schöngut ◽  
Ondřej Dammer ◽  
Josef Beránek ◽  
Aleš Zadražil ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Relaxation Measurement ◽  
Early Stages ◽  
Tablet Disintegration

Stress Relaxation Measurement Using SALS for Viscoelastic Fluid Flow in Serpentine Channel

2017 ◽  
Vol 2017.92 (0) ◽  
pp. M609
Author(s):  
Naoaki SHINOTSUKA ◽  
Kazuya TATSUMI ◽  
Reiko KURIYAMA ◽  
Kazuyoshi NAKABE
Keyword(s):  
Fluid Flow ◽  
Stress Relaxation ◽  
Viscoelastic Fluid ◽  
Relaxation Measurement ◽  
Serpentine Channel

Stress Relaxation Measurement as a High-Speed Method for Predicting the Long-Term Behavior of Vulcanized Rubber

1983 ◽  
Vol 56 (1) ◽  
pp. 31-50 ◽  
Author(s):  
R. Clamroth ◽  
L. Ruetz
Keyword(s):  
Stress Relaxation ◽  
High Speed ◽  
Elevated Temperatures ◽  
Pure Oxygen ◽  
Relaxation Measurement ◽  
Hot Air ◽  
Vulcanized Rubber ◽  
Relaxation Measurements ◽  
The Times ◽  
Speed Method

Abstract Intermittent stress relaxation is well suited for quantifying aging processes in rubber. For NR, the effects of different antioxidants can be measured by the rates at which the modulus falls. In synthetic rubbers (SBR, NBR, and CR), it can be measured through the modulus increases caused by oxygen crosslinking. Equal-value times, e.g., t0.75 for NR and t1.25 for SBR, NBR, and CR, are the times taken by the modulus to decrease or increase to a given percentage of its original level. They are better measures of aging than the modulus change after a given time. For NR, it has been shown that stress relaxation measurements at elevated temperatures and in pure oxygen correlate with the results of conventional aging methods. Thus the testing times can be drastically reduced—from up to 28 days to 1–8 hours. Discontinuous stress relaxation measurements are considerably more accurate and selective than conventional oxygen aging. For the repeatability of a single equal-value time measurement, we obtained a coefficient of variation (s/x) of 5–10% for stress relaxation measurement and about ±20% for oxygen aging. The degree of selectivity for oxygen aging and stress relaxation was found to be 3.6 and 18, respectively. The correlation between the results of stress relaxation measurements and those of the conventional oxygen and hot air aging tests was investigated for a large number of NR compounds and for some SBR, NBR, and CR compounds. The correlation is not very good, but it must be remembered that the equal-value times determined according to the two methods show relatively pronounced variability. With the conventional aging methods, the results also depend on what quantity is measured, e.g., the change in tensile strength or hardness, and on what equal-value time is chosen, e.g., the time taken by the property concerned to decrease to 90 or 75% of its original value. The conclusion of the investigations described above is that intermittent modulus measurement is an interesting high-speed method for the assessment of aging behavior. It will acquire a firm position in the arsenal of rubber testing methods, but will probably supplement, and not completely replace, the aging methods currently used.

The Development of a Real-Time Control System for Internal Mixers

1987 ◽  
Vol 60 (4) ◽  
pp. 618-635 ◽  
Author(s):  
P. K. Freakley ◽  
B. R. Matthews
Keyword(s):  
Control System ◽  
Stress Relaxation ◽  
Flow Behavior ◽  
Variable Speed ◽  
Relaxation Measurement ◽  
Real Time Control ◽  
Time Control ◽  
History Of ◽  
Batch Condition ◽  
Comprehensive History

Abstract The Batch Condition Control System has been shown to give good batch-to-batch repeatability of both viscous flow behavior and crosslinking characteristics for both fixed speed and variable speed mixing. It has also been shown to be capable of adjusting the mixing treatment to compensate for substantial changes in the properties of NR. Stress-relaxation results showed unexpectedly broad distributions. Lack of a comprehensive history of stress-relaxation results from the Negretti TMS biconical rotor rheometer makes it difficult to reach firm conclusions. The results for highly filled and thixotropic compounds are not comparable with those from other stress relaxometers such as the Monsanto SRPT and the BFGoodrich DSR, due to the small initial strain imposed on the sample by these instruments. Two possible causes of the broad distributions can be identified: 1) The sensitivity of the stress relaxation measurement. 2) The mode of flow in the chamber of a Farrel Banbury Mixer.

Relationships between Chemical Structures of Crosslink Sites and Physical Properties of Vulcanized Rubbers. Part VI. Oxidative Degradation of EPDM Vulcanizates

1970 ◽  
Vol 43 (2) ◽  
pp. 431-444 ◽  
Author(s):  
M. Imoto ◽  
Y. Minoura ◽  
K. Goto ◽  
H. Harada ◽  
K. Nishihira ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Physical Properties ◽  
Oxidative Degradation ◽  
Oxygen Absorption ◽  
Chemical Structures ◽  
Early Stages ◽  
Absorption Measurements

Abstract Relationship between the chemical structures of crosslinks and the degree of oxidative degradation of EPDM vulcanizates was studied by stress relaxation and oxygen absorption measurements. It was found that the vulcanizates having C—Sx—C crosslink showed slower stress relaxation than the vulcanizate having other crosslink structures, i.e., C—S—C, C—C, and C—R—C. It was thought that C—Sx—C bond would reduce the scission of the network in oxidative degradation, since some polysulfide compounds had the same effect of protecting scission as antioxidant. The similar results were obtained in oxygen absorption measurements. In the case of heat aging, the vulcanizate having C—Sx—C linkage increased in crosslinks during aging and the rate of crosslinking was equal to the rate of scission of the network in the early stages, but the vulcanizates having other types of crosslinks did not show such behavior.

scholarly journals Stress Relaxation Measurement of Fibroblast Cells with Atomic Force Microscopy

2007 ◽  
Vol 46 (8B) ◽  
pp. 5552-5555 ◽  
Author(s):  
Takaharu Okajima ◽  
Masaru Tanaka ◽  
Shusaku Tsukiyama ◽  
Tsubasa Kadowaki ◽  
Sadaaki Yamamoto ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Stress Relaxation ◽  
Fibroblast Cells ◽  
Relaxation Measurement ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Development of Stress Relaxation Measurement by a Small Size C-ring Specimen Method

2002 ◽  
Vol 1 (3) ◽  
pp. 263-269
Author(s):  
Shizuka SHIMANUKI ◽  
Kiyotomo NAKATA ◽  
Shigeki KASAHARA ◽  
Jiro KUNIYA
Keyword(s):  
Stress Relaxation ◽  
Relaxation Measurement ◽  
Ring Specimen

Frequency analysis of stress relaxation patterns reveals the effect of formulation and process history on tablet disintegration

2021 ◽  
Vol 379 ◽  
pp. 438-446
Author(s):  
Jan Tomas ◽  
Jakub Dvořák ◽  
Ondřej Dammer ◽  
František Štěpánek
Keyword(s):  
Stress Relaxation ◽  
Frequency Analysis ◽  
Tablet Disintegration
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