Creep Resistant Elastomer Formulations

1979 ◽  
Vol 52 (1) ◽  
pp. 50-73 ◽  
Author(s):  
J. F. Meier ◽  
G. E. Rudd ◽  
D. F. Weir
Keyword(s):  
Creep Rate ◽  
Service Life ◽  
Silicone Rubber ◽  
Relative Creep

Abstract Over 150 elastomer formulations of NR, DPNR, CR, IIR, AU, EU, EO, ECO, SBR, EPM, EPDM and a silicone rubber have been evaluated to identify the most creep resistant materials. Selected data are presented. Three of the best formulations (DPNR compound 15, CR compound 27 and EPDM compound 49) were found to give excellent creep performance extrapolating to less than 28% relative creep for a 15 year service life. As a result of a requirement for 15 year resistance to 25 pphm O3 concentration, EPDM formulation 49 was selected, and pads were molded and compression tested. Because of the O3 resistance of EPDM, there should not be a significant increase in creep rate.

Service Life Prediction of Liquid Silicone Rubber Seal in PEM Fuel Cells

2010 ◽  
Author(s):  
Tong Cui ◽  
C.-W. Lin ◽  
C.-H. Chien ◽  
Y. J. Chao ◽  
J. Van Zee
Keyword(s):  
Fuel Cell ◽  
Service Life ◽  
Silicone Rubber ◽  
Proton Exchange Membrane ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Liquid Silicone Rubber ◽  
Liquid Silicone ◽  
Exchange Membrane ◽  
Near Future

Proton exchange membrane fuel cell (PEMFC) is a promising power source for automobiles in the near future. During operation, there are gases and liquids inside the fuel cell. Sealing around the perimeter of the cell is therefore required to prevent the gases/liquids inside the cell from leaking. Polymers are usually used as the sealing or gasket materials. They in general possess the property of viscoelasticity. The stress relaxation behavior of a polymer, liquid silicone rubber, is studied in this article. Applying the time-temperature superposition, master curve is generated for the prediction of service life of this material used as seals in PEMFC.

Effect of Surface Condition on Creep of Some Commercial Metals

1953 ◽  
Vol 20 (1) ◽  
pp. 30-32
Author(s):  
E. D. Sweetland ◽  
E. R. Parker
Keyword(s):  
Surface Layer ◽  
Creep Rate ◽  
Axial Stress ◽  
Surface Condition ◽  
Pure Copper ◽  
Inert Atmosphere ◽  
Oxide Surface ◽  
Secondary Creep ◽  
Before And After ◽  
Relative Creep

Abstract The relative creep rate of specimens of 2S aluminum and commercial drawn copper were investigated with the oxide surface layers removed and then, under the same conditions, after the oxide was permitted to form. The oxide was removed mechanically by stripping the test specimens in an inert atmosphere furnace so equipped that an axial stress could be applied and the creep rate determined without disturbing the atmosphere. After the oxide-free specimen was observed to be creeping essentially linearly with time (i.e., the quasiviscous, secondary creep range was established), air was admitted to the furnace. The extension versus time plot was continued after admission of air and the temperature held constant. Since all of the known parameters affecting creep rate (temperature, grain size, degree of work hardening, stress, and so on) except the gaseous environment were the same before and after admitting air, the effect of this change could be isolated. A decrease in creep rate was observed after air had been admitted to the furnace. These experimental results indicate that the presence of an oxide surface layer on the commercial grades of pure copper and aluminum increases the creep strength of these metals. The manner in which this relatively thin surface layer contributes to the strength of the parent metal is not clear, but the phenomenon is consistent with the theory of dislocations as presented by G. I. Taylor if it is assumed that the oxide inhibits the generation and/or migration of dislocations.

TEM of grain growth and phase transformations during creep of SCS-6 silicon carbide fibers

1995 ◽  
Vol 53 ◽  
pp. 350-351
Author(s):  
L. A. Giannuzzi ◽  
C. A. Lewinsohn ◽  
C. E. Bakis ◽  
R. E. Tressler
Keyword(s):  
Silicon Carbide ◽  
Creep Rate ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Primary Creep ◽  
Excess Carbon ◽  
Silicon Carbide Fibers ◽  
Sic Fiber ◽  
Carbon Core ◽  
Grain Width

The SCS-6 SiC fiber is a 142 μm diameter fiber consisting of four distinct regions of βSiC. These SiC regions vary in excess carbon content ranging from 10 a/o down to 5 a/o in the SiC1 through SiC3 region. The SiC4 region is stoichiometric. The SiC sub-grains in all regions grow radially outward from the carbon core of the fiber during the chemical vapor deposition processing of these fibers. In general, the sub-grain width changes from 50nm to 250nm while maintaining an aspect ratio of ~10:1 from the SiC1 through the SiC4 regions. In addition, the SiC shows a <110> texture, i.e., the {111} planes lie ±15° along the fiber axes. Previous has shown that the SCS-6 fiber (as well as the SCS-9 and the developmental SCS-50 μm fiber) undergoes primary creep (i.e., the creep rate constantly decreases as a function of time) throughout the lifetime of the creep test.

Computing cell tractions from particle displacements on silicone rubber substrata

1994 ◽  
Vol 52 ◽  
pp. 162-163
Author(s):  
Tim Oliver ◽  
Akira Ishihara ◽  
Ken Jacobsen ◽  
Micah Dembo
Keyword(s):  
Plane Stress ◽  
Linear Elasticity ◽  
Silicone Rubber ◽  
Mathematical Analysis ◽  
Elastic Recovery ◽  
Video Images ◽  
Cell Traction Forces ◽  
Latex Beads ◽  
Cell Traction ◽  
Better Than

In order to better understand the distribution of cell traction forces generated by rapidly locomoting cells, we have applied a mathematical analysis to our modified silicone rubber traction assay, based on the plane stress Green’s function of linear elasticity. To achieve this, we made crosslinked silicone rubber films into which we incorporated many more latex beads than previously possible (Figs. 1 and 6), using a modified airbrush. These films could be deformed by fish keratocytes, were virtually drift-free, and showed better than a 90% elastic recovery to micromanipulation (data not shown). Video images of cells locomoting on these films were recorded. From a pair of images representing the undisturbed and stressed states of the film, we recorded the cell’s outline and the associated displacements of bead centroids using Image-1 (Fig. 1). Next, using our own software, a mesh of quadrilaterals was plotted (Fig. 2) to represent the cell outline and to superimpose on the outline a traction density distribution. The net displacement of each bead in the film was calculated from centroid data and displayed with the mesh outline (Fig. 3).

Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes

1993 ◽  
Vol 51 ◽  
pp. 188-189
Author(s):  
Tim Oliver ◽  
Michelle Leonard ◽  
Juliet Lee ◽  
Akira Ishihara ◽  
Ken Jacobson
Keyword(s):  
Silicone Rubber ◽  
Molecular Motors ◽  
Video Frame ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Latex Beads ◽  
Cell Traction ◽  
Local Cell ◽  
Microscopic Measurement ◽  
Kinetics Of

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.

Performance study of RTV-2 Silicone Rubber Material For Soft Actuator by Experimental and Numerical methods: The Effect of Inflation Pressure and Wall Thickness

2020 ◽  
Vol 17 (1) ◽  
pp. 7524-7532 ◽  
Author(s):  
Deepak D. ◽  
Nitesh Kumar ◽  
Shreyas P. Shetty ◽  
Saurabh Jain ◽  
Manoj Bhat
Keyword(s):  
Numerical Methods ◽  
Wall Thickness ◽  
Silicone Rubber ◽  
Inflation Pressure ◽  
Performance Study ◽  
Rubber Material ◽  
Soft Actuator ◽  
Alternative Materials ◽  
Load Carrying ◽  
Influential Parameters

The expensive nature of currently used materials in the soft robotic industry demands the consideration of alternative materials for fabrication. This work investigates the performance of RTV-2 grade silicone rubber for fabrication of a soft actuator. Initially, a cylindrical actuator is fabricated using this material and its performance is experimentally assessed for different pressures. Further, parametric variations of the effect of wall thickness and inflation pressure are studied by numerical methods. Results show that, both wall thickness and inflation pressure are influential parameters which affect the elongation behaviour of the actuator. Thin (1.5 mm) sectioned actuators produced 76.97% more elongation compared to thick sectioned, but the stress induced is 89.61 % higher. Whereas, the thick sectioned actuator (6 mm) showed a higher load transmitting capability. With change in wall thickness from 1.5 mm to 6 mm, the elongation is reduced by 76.97 %, 38.35 %, 21.05 % and 11.43 % at pressure 100 kPa, 75 kPa, 50 kPa and 25 kPa respectively. The induced stress is also found reduced by 89.61 %, 86.66 %, 84.46 % and 68.68 % at these pressures. The average load carrying capacity of the actuator is found to be directly proportional to its wall thickness and inflation pressure.

Sign in / Sign up

Export Citation Format

Share Document