The Compression Set Behavior of Nitrile Rubber

1973 ◽  
Vol 46 (1) ◽  
pp. 305-330 ◽  
Author(s):  
H-J. Jahn ◽  
H-H. Bertram
Keyword(s):  
Test Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Nitrile Rubber ◽  
Compression Set ◽  
Test Pieces ◽  
Steep Part ◽  
Cure Time ◽  
Different Temperatures ◽  
Lower Test

Abstract The compression set (C.S.) of a vulcanizate depends on the formulation, processing, and conditions of cure. The following factors are the most important: (a) the type of elastomer, (b) the curing system, (c) the type and amount of filler, (d) the type and amount of plasticizer, (e) the type and amount of antioxidant, (f) the type of cure (press, steam, or hot air), and (g) the cure time and temperature. The present paper is intended, as far as possible, to describe these relationships quantitatively. Most tests will refer to nitrile rubber. We have modified the C.S. method described in ASTM D-395. The deviations are as follows : (1) When C.S. is plotted as a function of the duration of compression, the resulting curves rise steeply for roughly the first seven days, afterwards becoming flatter. The higher the test temperature, the steeper the curve. The ordinary compression times of 22 and 70 h still correspond to the steep part of the C.S. curve; here relatively small inaccuracies in the compression time and test temperature bring large errors in the C.S. readings. Therefore, to improve the correlation between C.S. readings and field behavior the test was extended to seven days in most cases. Longer test times would have been experimentally impractical. (2) As a rule, only C.S. figures relating to 20°, 70°, and 100° C are found in the literature, so test temperatures were extended to include practical conditions. Generally, therefore, C.S. readings were taken at twelve different temperatures ranging from −60° C to +160° C. (3) According to the standards the test pieces should be cooled to room temperature after removal of the load and before the recovery measurement is carried out. Only ASTM D-1229-62 requires the remeasurement to be taken at the load temperature. This ensures accurate measurements of the C.S. at low temperatures. In our tests this was done in every case because at high temperature the C.S. readings are lower since (1) many elastomers recover better at elevated temperatures than at room temperature and (2) the thermal expansion of the test piece can be measured in addition to the recovery. Nevertheless, the differences between remeasurements taken at room temperature and the test temperature are small if the test temperature is fairly high. Where lower test temperatures are used, the remeasurement should always be taken at test temperature if useful results are to be obtained. In all the tests the time allowed for recovery between removal of the load and the remeasurement was thirty min.

Thermooxidative Aging Studies on Silicone Rubber and Lifetime Prediction

2013 ◽  
Vol 777 ◽  
pp. 11-14
Author(s):  
You Shan Wang ◽  
Sha Sha Jiang ◽  
Yu Peng Liu
Keyword(s):  
Silicone Rubber ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Activation Energies ◽  
Lifetime Prediction ◽  
Arrhenius Behavior ◽  
Compression Set ◽  
Degradation Processes ◽  
Aging Studies ◽  
Significant Compression

Silicone rubber have been aged in air while under 25% compression at temperature up to 250°C. These studies examined the compression set of silicone rubber at accelerated (elevated) temperatures and were then used to make predictions about compression set at room temperature. The data obtained could be amenable to timetemperature superposition and Arrhenius treatment. The results suggest the presence of two degradation processes with activation energies of 71.6 kJ mol-1 (for temperatures above 165 °C) and 26.08 kJ mol-1 (for temperatures below 165 °C). Based on the extrapolation of the non-Arrhenius behavior, it was estimated that significant compression set loss would occur after around 67 years at 25 °C.

An Ultrasonic Non-Contact Handling Device from Quartz Glass for Middle and High Temperature Applications

2014 ◽  
Vol 1018 ◽  
pp. 31-38
Author(s):  
Edgars Locmelis
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Manufacturing Processes ◽  
Mechanical Contact ◽  
High Temperature Region ◽  
Handling Device ◽  
Design And Manufacturing ◽  
Different Temperatures ◽  
Small Change

Ultrasonic non-contact handling is used to manipulate surface sensitive and fragile workpieces, e.g. wafers and glass plates, without mechanical contact. While the technology is available forapplications at room temperature, some of the manufacturing processes of products mentioned aboverequire handling at elevated temperatures. To enable this technology for handling in thermal processesan ultrasonic system for increased working temperatures is required. In order to adapt the ultrasonicsystem to the limited working temperature of the actuator, the handling system has to be operated attwo different temperatures. Due to the small change of the Young's modulus over temperature, quartzglass was chosen as material for the components in the high temperature region. The paper presentsthe design and manufacturing of a novel ultrasonic system operated at 790 °C while the actuator iskept at room temperature.

Wandering of Crosslinks in Rubber at High Temperature

1959 ◽  
Vol 32 (3) ◽  
pp. 696-700
Author(s):  
M. J. Voorn ◽  
J. J. Hermans
Keyword(s):  
Stress Relaxation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Crosslinking Density ◽  
Heat Treated Sample ◽  
Equilibrium Degree ◽  
Heat Treated ◽  
Before And After ◽  
Final Stress ◽  
Different Temperatures

Abstract There are strong reasons to believe that on heating a crosslinked rubber crosslinks are broken and new ones formed. This has been established by the well-known work on stress relaxation of Tobolsky and his school, and others. In the following we will discuss some experiments which give further support to these views, both of a qualitative and quantitative nature. In the first place, we carried out a few preliminary experiments on stress relaxation at elevated temperatures. This stress relaxation may be due to either or both of two effects : (a) a displacement of the crosslinks, (b) a change in the number of crosslinks per unit of volume (crosslinking density p). A measure of ρ can be obtained from the equilibrium degree of swelling at room temperature, and this gives us a means of comparing changes of ρ in a stretched sample with those occurring in the unstretched state. To this end commercial rubber strips were heated in the stretched state in the absence of oxygen at three different temperatures (80, 106, 122° C) for times varying from 2 to 72 hours. The degree of stretch, i.e., the length of the stretched rubber divided by the original length was α=1 (unstretched) in one series, and α=3 in a second series. The initial stress τ0 (for α=3) and the final stress τ at the end of the heating period were read from the stress-strain diagrams, taking into account that for the heat-treated strips there was a permanent set. In other words, τ is the stress needed to give the heat-treated sample at room temperature a length 3 times the length of the original untreated sample; the ratio τ/τ0 is therefore essentially the ratio between the moduli of elasticity. The cross-linking densities ρ0 and ρ before and after heating were derived from swelling experiments (for details see the sections on swelling).

Symmetry Changes At The Surface Of Al70Pd20Mn10

1998 ◽  
Vol 553 ◽  
Author(s):  
B. Bolliger ◽  
M. Erbudak ◽  
A. Hensch ◽  
A.R. Kortan ◽  
D.D. Vvedensky
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Surface Composition ◽  
Structural Phase ◽  
Bulk Composition ◽  
Icosahedral Quasicrystal ◽  
Icosahedral Symmetry ◽  
Structural Phase Transitions ◽  
Structure Changes ◽  
Different Temperatures

AbstractSputtering with Ar+ ions induces structural phase transitions at the pentagonal surface of the icosahedral quasicrystal Al70Pd20Mn10. Sputtering at different temperatures changes the surface composition, thereby stabilizing different structures. At room temperature, the structure changes to body-centered cubic but, at elevated temperatures, it displays decagonal symmetry. In both cases, annealing the sample restores both the bulk composition and the icosahedral symmetry of the original surface.

An integrated experimental and finite element approach for wrinkling limit prediction of Inconel 718 alloy at elevated temperatures

2021 ◽  
pp. 030932472110430
Author(s):  
Gauri Mahalle ◽  
Nitin Kotkunde ◽  
Amit Kumar Gupta ◽  
Swadesh Kumar Singh
Keyword(s):  
Finite Element ◽  
Elevated Temperature ◽  
Inconel 718 ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Functional Requirements ◽  
Inconel 718 Alloy ◽  
Different Temperatures ◽  
Post Buckling ◽  
Element Approach

Wrinkling is generally induced because of metal instability and considered as an undesirable defect in sheet metal forming processes. Wrinkling leads to severe influence on functional requirements and aesthetic appeal of final component. Thus, the present research is mainly dedicated on the experimental and numerical analysis for wrinkling behavior prediction of Inconel 718 alloy at elevated temperature conditions. Initially, Yoshida buckling tests (YBT) have been conducted to investigate wrinkling tendencies of Inconel 718 alloy from room temperature (RT) to 600°C by an interval of 200°C. Subsequently, Finite Element (FE) analysis of YBT has been performed to analyze post buckling behavior. Critical strain values at onset of wrinkling are determined and strain based wrinkling limit curves (ε-WLCs) are plotted at different temperatures. In-plane principal strains are transferred to effective plastic strain (EPS) versus triaxiality (η) space to differentiate the transformation between safe and wrinkling instability. Finally, complete forming behavior of alloy is represented by means of fracture, forming, and wrinkling limit curves. The gap between forming and wrinkling limit curves at elevated temperature is ∼1.5 times higher than that at room temperature.

Channeled Implantations of p-Type Dopants into 4H-SiC at Different Temperatures

2019 ◽  
Vol 963 ◽  
pp. 382-385 ◽  
Author(s):  
Margareta K. Linnarsson ◽  
Anders Hallén ◽  
Lasse Vines ◽  
Bengt G. Svensson
Keyword(s):  
Room Temperature ◽  
Depth Distribution ◽  
Elevated Temperatures ◽  
Secondary Ion Mass Spectrometry ◽  
Lattice Vibrations ◽  
Simulation Code ◽  
Different Temperatures ◽  
P Type ◽  
Secondary Ion ◽  
Collision Approximation

Channeling of B and Al ions in 4H-SiC(0001), has been investigated by secondary ion mass spectrometry (SIMS). Ion implantations have been performed between room temperature (RT) and 600 °C at various fluences. Before implantation, the major crystal axes were determined and the sample was aligned using the blocking pattern of backscattered protons. As expected, the depth distribution of the implanted ions along a crystal direction penetrates much deeper compared to non-channeling directions. At elevated temperatures, the channeling depth for 100 keV Al-ions is decreased due to lattice vibrations. For 50 keV B-ions, the temperature effect is minor, indicating a smaller interaction between target atoms and B. Simulations has been performed using SIIMPL, a Monte Carlo simulation code based on the binary collision approximation, to predict experimental data and get a deeper insight in the channeling process.

Effect of Annealing on Fracture Toughness Evaluation of Ba0.5Sr0.5Co0.8 Fe0.2O3−δ (BSCF) at Different Temperatures

2014 ◽  
Vol 592-594 ◽  
pp. 816-820 ◽  
Author(s):  
Bablu Sikder ◽  
Abhijit Chanda
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Stress ◽  
Compressive Residual Stress ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Toughness Evaluation ◽  
Different Temperatures ◽  
Fracture Toughness Evaluation ◽  
Typical Variation

An experimental study on the fracture toughness of BSCF samples were conducted at room temperature as well as elevated temperatures (upto 800°C). The results showed a typical variation of fracture toughness and fracture stress with temperature. It decreased upto 600°C and then increased to reach a comparatively higher value at 800°C. Without annealing the samples showed comparatively higher fracture toughness because of the presence of compressive residual stress.

Fracture Toughness of Two Cr2Hf+Cr Intermetallic Composites as a Function Temperature

1994 ◽  
Vol 350 ◽  
Author(s):  
K. S. Ravichandran ◽  
D. B. Miracle ◽  
M. G. Mendiratta
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Test Temperature ◽  
Room Temperature ◽  
Heat Treated ◽  
Coarse Microstructure ◽  
Lower Test ◽  
Ductile Behavior

AbstractFracture toughness as a function of temperature was evaluated for two Cr2Hf+Cr intermetallic composites, each in two different microstructural conditions. The proeutectic microstructures based on Cr-6.5Hf (at%) showed a significant increase in fracture toughness with an increase from room temperature to 600°C. The coarse microstructure obtained by heat treatment at 1500°C showed evidence of ductile behavior of Cr at a lower test temperature (200°C) relative to that of one heat treated at 1250°C (400'C). In the eutectic microstructures based on Cr-13Hf, only a small increase in fracture toughness at 600°C was seen. The results are analyzed in the light of fracture micromechanisms.

scholarly journals The Investigation of Microstructure and Mechanical Behavior and the Fractographic Analysis of the Ti49.1Ni50.9 Alloy in States with Different Activation Deformation Volumes

2021 ◽  
Vol 11 (7) ◽  
pp. 3052
Author(s):  
Anna Churakova ◽  
Dmitry Gunderov ◽  
Elina Kayumova
Keyword(s):  
Mechanical Behavior ◽  
Test Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Fractographic Analysis ◽  
Coarse Grained ◽  
Ultrafine Grained ◽  
Coarse Grained State ◽  
Different Temperatures

In this article, the microstructure and mechanical behavior of the Ti49.1Ni50.9 alloy with a high content of nickel in a coarse-grained state, obtained by quenching, ultrafine-grained (obtained through the equal-channel angular pressing (ECAP) method) and nanocrystalline (high pressure torsion (HPT) + annealing), were investigated using mechanical tensile tests at different temperatures. Mechanical tests at different strain rates for determining the parameter of strain rate sensitivity m were carried out. Analysis of m showed that with an increase in the test temperature, an increase in this parameter was observed for all studied states. In addition, this parameter was higher in the ultrafine-grained state than in the coarse-grained state. The activation deformation volume in the ultrafine-grained state was 2–3 times greater than in the coarse-grained state at similar tensile temperatures. Fractographic analysis of samples after mechanical tests was carried out. An increase in the test temperature led to a change in the nature of fracture from quasi-brittle–brittle (with small pits) at room temperature to ductile (with clear dimples) at elevated temperatures. Microstructural studies were carried out after the tensile tests at different temperatures, showing that at elevated test temperatures, the matrix was depleted in nickel with the formation of martensite twins.

scholarly journals Effect of Elevated Temperatures on Fiber Reinforced Self Compacting Concrete

2019 ◽  
Vol 8 (3) ◽  
pp. 7775-7778
Keyword(s):  
Compressive Strength ◽  
Temperature Effects ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Steel Fibers ◽  
Muffle Furnace ◽  
Self Compacting Concrete ◽  
Retention Period ◽  
Steel Fibres ◽  
Different Temperatures

The present investigation is mainly focused on study the temperature effects on SCC reinforced with steel fibers on M40 grade of concrete. The main objective of the investigation is inspired from the real world - to know the strength of a concrete after subjected to an elevated temperature. Steel fibres with an aspect ratio of 40varied at a fibre dosage of 0, 1, and 1.5%by the weight of the cement used in this investigation. In this study concrete is exposed to five different residual conditions. In addition to the room temperature there are four different temperatures of 100˚c, 300˚c, 500˚c and 800˚c are considered at a retention period of 1, 2, 3 and 4 hours in muffle furnace. Compressive strength conducted after 28 days of curing. From the experimental results it is observed that SCC with steel fibres reduced the workability on the contrary there is increase in compressive strength observed with the addition of fibres. It is also observed that SCC with steel fibres has shown the better performance compared to control mix at elevated temperatures. This is mainly due to fibres are participated in delaying the cracks.

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