The Goodrich Flexometer

1938 ◽  
Vol 11 (1) ◽  
pp. 249-262 ◽  
Author(s):  
E. T. Lessig
Keyword(s):  
Heat Generation ◽  
Test Piece ◽  
Applied Load ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Simple Design ◽  
Test Pieces ◽  
Rubber Compounds ◽  
Rubber Fabric

Abstract The Goodrich flexometer is of simple design and is easily operated at ordinary or elevated temperatures. Test pieces procured from laboratory specimens or from finished rubber or rubber-fabric products may be tested, using moderate loads that produce equilibrium temperatures during flexure or larger loads that rupture the test piece. This machine may be used to study the effects on heat generation of the time of cure, the magnitude of the applied load, changes in pigmentation, and variations caused by anisotropy in rubber compounds. It is so designed that the structural changes such as softening or stiffening may be followed during the period of flexure.

Natural Rubber Compounds for Truck Tires

1985 ◽  
Vol 58 (4) ◽  
pp. 740-750 ◽  
Author(s):  
D. Barnard ◽  
C. S. L. Baker ◽  
I. R. Wallace
Keyword(s):  
Stearic Acid ◽  
Heat Generation ◽  
Rolling Resistance ◽  
Synthetic Compound ◽  
Wear Performance ◽  
Test Pieces ◽  
Truck Tire ◽  
Truck Tires ◽  
Rubber Compounds ◽  
Lower Severity

Abstract An 80 NR/20 BR truck tread compound containing a semi-EV cure system and modified with a 6.0 phr level of stearic acid has been shown to exhibit excellent resistance to reversion when compared to a similar compound containing a normal 2.0 phr level of stearic acid. Improvements in the retention of laboratory abrasion resistance, heat generation, and most physical properties have been identified on test pieces subjected to typical truck retread overcure conditions. In highway fleet testing trials of 1100 × 22.5 truck retreads fitted to both third and fourth drive axles of tipper trucks, the modified compound displayed a 42% improvement in treadwear performance over the normal compound in the lower severity third axle positions while performance in the higher severity fourth axle positions was inferior by 20%. In comparison to a 55 SBR/45 BR truck tread, both NR compounds displayed superior wear performance on the fourth axles while some further adjustments of the modified compound are required to match the synthetic compound on the third axles. The reversal of wear performances for all compounds between third and fourth axles is due to the different abrasion mechanisms encountered. Laboratory abrasion rankings do not correlate with wear performances of compounds on the fourth drive axle of trucks, but they do correlate with wear performances on third drive axles. Despite the reversion characteristics of the normal semi-EV compound, no significant adverse effect on treadwear performance was evident at the start of tire life. The low heat generation of the modified compound in laboratory tests is confirmed in actual tire testing. Advantages in rolling resistance characteristics are also evident for the modified compound. Current studies at MRPRA suggest that further modifications of cure system design, in combination with the optimization of NR/BR ratios and mixing methods, will potentially provide NR dominant truck tread compounds which will exhibit superior wear performance in both the higher and lower abrasion severities encountered in heavy-duty truck tire service conditions.

An Interchangeable Turning Sprue Bushing in a Multi Cavity Family Injection Mold

2012 ◽  
Vol 548 ◽  
pp. 600-604
Author(s):  
Rozana Mohd Dahan ◽  
Saiful Bahri Mohd Yasin ◽  
Zakaria Razak ◽  
Mohd Helmi Omar
Keyword(s):  
Temperature Distribution ◽  
Test Piece ◽  
Volume Shrinkage ◽  
Injection Mold ◽  
Melt Flow ◽  
Flexural Test ◽  
Test Pieces ◽  
The Family ◽  
Separate Injection

Interchangeable Turning Sprue Bushing (ITSB) is a small insert at the centre of core side used to change runner directions for injecting 2 different products in a separate injection mold by shifting the melt filling to the cavities. The development of ITSB is significant in cutting down cost and time consumed during fabrication of a multi cavity family mold. In this study, the tensile and flexural test pieces were designed using CAD Solidwork. The test pieces analysis was performed using CAE Cadmould simulation in order to observe the melt flow of four multi cavities family mold incorporated without and with ITSB insert. The Cadmould simulation was used specifically to analyse the melt filling, temperature distribution and volume shrinkage of the test pieces. The simulation result demonstrated that ITSB is a useful insert that can be used to overcome problems encountered in the family mold system by balancing the melt filling, minimize temperature distribution and reduced the differential of volume shrinkage of the test piece manufactured. ITSB also reduced the frequent defects formed during production such as short molding, flashing and warpage.

X-ray diffraction investigations of structural changes in Co/Cu multilayers at elevated temperatures

2002 ◽  
Vol 411 (2) ◽  
pp. 234-239 ◽  
Author(s):  
M Hecker ◽  
W Pitschke ◽  
D Tietjen ◽  
C.M Schneider
Keyword(s):  
Structural Changes ◽  
Elevated Temperatures ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Research of the properties of rubber-cord composites in the presence of new adhesion promoters

2020 ◽  
Vol 82 (3) ◽  
pp. 221-226
Author(s):  
O. V. Karmanova ◽  
S. G. Tikhomirov ◽  
E. V. Lintsova ◽  
L. V. Popova
Keyword(s):  
Elevated Temperatures ◽  
Tensile Elongation ◽  
Physical And Mechanical Properties ◽  
Cobalt Content ◽  
Strength Properties ◽  
Adhesion Promoters ◽  
Serial Sample ◽  
Rubber Compounds ◽  
The Cost ◽  
Processing Properties

Studies of experimental adhesion modifiers based on a mixture of fatty acids from the production of light vegetable oils. The properties of rubber compounds and their vulcanizates obtained using experimental adhesion promoters KK with cobalt content from 7.5 to 16.5% are investigated. The plastic-elastic and vulcanization properties of the properties of breaker rubber compounds based on polyisoprene, the physical and mechanical properties of breaker rubbers and the bond strength in the “rubber-brass-plated steel cord system” were studied. When testing belt rubbers containing experienced adhesion promoters or an imported analog of Manobond 680C, the following features were revealed. The plasticity of the prototypes was in the range of 0.2-0.4. This indicates satisfactory processing properties. The Mooney viscosity of the prototypes was lower than that of the production sample. The use of experienced adhesion promoters instead of the analogue (Manobond 680C) increases the resistance to scorching. On the basis of the analysis of elastic-strength properties, it was found that in terms of the conditional tensile strength, the prototypes were inferior to the serial ones. However, rubbers containing the KK-12, KK-13.5, KK-15 promoters met the control standards. The tensile elongation at break of the experimental rubbers is higher than that of the serial sample. This may indicate the formation of a more uniform cure network in the presence of the test products. When testing rubber-metal-hard composites, it was noted that, under normal conditions, the experienced adhesion promoters have advantages over Manobond 680C. However, at elevated temperatures, under conditions of salt and steam-air aging, they are slightly inferior to Manobond 680C. It has been established that the experimental adhesion promoters provide the required set of technical properties of belt rubbers with a CO2 + content of 12–16.5% wt. Thus, it is possible to recommend the adhesion promoters KK 12, KK-13.5, KK 15 for practical use in the composition of belt rubber compounds. This will allow replacing a foreign-made product and reducing the cost of production.

scholarly journals A Bis-Monophospholyl Dysprosium Cation Showing Magnetic Hysteresis at 48 Kelvin

2019 ◽  
Author(s):  
Peter Evans ◽  
Daniel Reta ◽  
George F. S. Whitehead ◽  
Nicholas Chilton ◽  
David Mills
Keyword(s):  
Data Storage ◽  
Single Molecule ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Spin Dynamics ◽  
Magnetic Hysteresis ◽  
Relaxation Times ◽  
Magnetic Memory ◽  
Relaxation Processes ◽  
Potential Applications

Single-molecule magnets (SMMs) have potential applications in high-density data storage, but magnetic relaxation times at elevated temperatures must be increased to make them practically useful. <i>Bis</i>-cyclopentadienyl lanthanide sandwich complexes have emerged as the leading candidates for SMMs that show magnetic memory at liquid nitrogen temperatures, but the relaxation mechanisms mediated by aromatic C<sub>5</sub> rings have not been fully established. Here we synthesise a <i>bis</i>-monophospholyl dysprosium SMM [Dy(Dtp)<sub>2</sub>][Al{OC(CF<sub>3</sub>)<sub>3</sub>}<sub>4</sub>] (<b>1</b>, Dtp = {P(C<sup>t</sup>BuCMe)<sub>2</sub>}) by the treatment of <i>in situ</i>-prepared “[Dy(Dtp)<sub>2</sub>(C<sub>3</sub>H<sub>5</sub>)]” with [HNEt<sub>3</sub>][Al{OC(CF<sub>3</sub>)<sub>3</sub>}<sub>4</sub>]. SQUID magnetometry reveals that <b>1</b> has an effective barrier to magnetisation reversal of 1,760 K (1,223 cm<sup>–1</sup>) and magnetic hysteresis up to 48 K. <i>Ab initio</i> calculation of the spin dynamics reveal that transitions out of the ground state are slower in <b>1</b> than in the first reported dysprosocenium SMM, [Dy(Cp<sup>ttt</sup>)<sub>2</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] (Cp<sup>ttt</sup> = C<sub>5</sub>H<sub>2</sub><sup>t</sup>Bu<sub>3</sub>-1,2,4), however relaxation is faster in <b>1</b> overall due to the compression of electronic energies and to vibrational modes being brought on-resonance by the chemical and structural changes introduced by the <i>bis</i>-Dtp framework. With the preparation and analysis of <b>1</b> we are thus able to further refine our understanding of relaxation processes operating in <i>bis</i>-C<sub>5</sub>/C<sub>4</sub>P sandwich lanthanide SMMs, which is the necessary first step towards rationally achieving higher magnetic blocking temperatures in these systems in future.

Experimental Investigation on Grinding Temperature of Titanium Alloy

2014 ◽  
Vol 1027 ◽  
pp. 127-130 ◽  
Author(s):  
Bing Jun Hao ◽  
Zhi Gang Dong ◽  
Ren Ke Kang ◽  
Huan Wang ◽  
Ke Cao
Keyword(s):  
Titanium Alloy ◽  
Structural Changes ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Chemical Properties ◽  
Grinding Temperature ◽  
Physical And Chemical Properties ◽  
Machine Material ◽  
Physical And Chemical ◽  
And Chemical Properties

Titanium alloy has been widely used in aeronautics and astronautics industry owing to its unique combinations of properties. The unique physical and chemical properties of titanium alloy make it a typical difficult-to-machine material. The elevated temperatures at the machining zones may cause thermal damage, residual stress and micro-structural changes in the surface layer of titanium alloy during grinding. In this study, grinding experiments were performed on the titanium alloy, and the grinding temperature was experimentally tested with the grindable thermocouples. The effects of the grinding parameters on the grinding temperature were analyzed. The grinding temperature rises with the increase of grinding speed and grinding depth.

Network Changes in Nitrile Rubber at Elevated Temperatures

1973 ◽  
Vol 46 (2) ◽  
pp. 483-503 ◽  
Author(s):  
T. C. P. Lee ◽  
S. H. Morrell
Keyword(s):  
Heat Resistance ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Essential Feature ◽  
Nitrile Rubber ◽  
Polymer Backbone ◽  
Thermal Changes ◽  
Effective Antioxidant ◽  
Cleavage Reactions ◽  
Crosslinking Reactions

Abstract The network analysis of the aged sulfur vulcanizates of nitrile rubber serves to re-emphasize the complexity of the structural changes which can occur at elevated temperatures. Three factors control the rate and degree of crosslinking in these systems. First there is the crosslink structure. An essential feature for heat resistance in sulfur compounds is that they should contain, as near as possible, 100 per cent monosulfide crosslinks. Systems which contain polysulfide crosslinks, and probably to a lesser extent disulfide crosslinks, are prone to purely thermal crosslink shortening or cleavage reactions. The physical effect of these thermal changes would be superimposed on the effects brought about by thermooxidative changes. Despite their thermal stability monosulfide crosslinks can oxidize and cleave, a process which will result in stress relaxation if the sample is held in tension or compression. Hence for truly inert systems one will have to turn to non-sulfur cure in conjunction with a suitable stabilizer. Because the results indicate that scission associated with chemistry at the monosulfide crosslink is reversible, this cleavage does not contribute to the change in modulus or hardening during aging. This brings in the second controlling factor. The degree and rate of hardening depends on the nature of the products of vulcanization, and also possibly on those species intermediate between crosslink and accelerator, the pendent accelerator groups. In acting as an antioxidant ZDMC is apparently oxidized to a new source of sulfur. The more heat resistant cadmate system contains no such products and also a minimum of pendent accelerator groups. This leads to the third factor—the added antioxidant. For its heat resistance the cadmate system relies on an antioxidant. It is this which stops crosslinking reactions through autooxidation of the polymer backbone. The efficiency with which the antioxidant (dioctyldiphenylamine) works suggests that there is a synergistic effect in operation, which in some way involves cadmium. Thus the best heat resistance will be obtained where the compound yields monosulfide crosslinks, an uncomplicated network structure, unreactive vulcanization products, and contains a highly effective antioxidant system. Many facets of the aging of nitrile rubber are still open to explanation. Not the least of these is why crosslinks formed during the aging of the TMTD/S vulcanizate, which, by reason of their reactivity to methyl iodide, are thought to be sulfidic, are not themselves oxidized in a manner similar to the original monosulfide crosslinks. Model compound studies would answer this and other questions.

Mechanical and Basic Physical Properties of High-Strength Concrete Exposed to Elevated Temperatures

2018 ◽  
Vol 760 ◽  
pp. 108-113 ◽  
Author(s):  
Lenka Scheinherrová ◽  
Monika Čáchová ◽  
Michaela Petříková ◽  
Lukáš Fiala ◽  
Eva Vejmelková ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Water Environment ◽  
High Strength ◽  
Steel Fibers ◽  
Quartz Powder ◽  
Matrix Density ◽  
Drying Treatment

In this paper, the effect of elevated temperatures on the mechanical and basic properties of two different newly-designed high-strength concretes is studied. The studied materials were prepared from Portland cement, steel fibers, reactive finely milled quartz powder and quartz sand, silica fume, plasticizer, and with a relatively low water/cement ratio of 0.24. The samples were stored in water environment for the first 28 days of hydration to achieve better mechanical properties. Then, after pre-drying at 105 °C to constant mass, the materials were exposed to elevated temperatures of 600 °C and 1000 °C where they were kept for 2 hours. The basic physical properties, such as matrix density, bulk density and open porosity were determined as a function of temperature. Mechanical properties (compressive and flexural strength) were also studied. The measured parameters exhibited a high dependence on temperature and the obtained results pointed to the structural changes of the studied materials. Spalling was not observed because of the pre-drying treatment.

Structural variations in strained crystalline multilayers

1994 ◽  
Vol 9 (8) ◽  
pp. 2190-2197 ◽  
Author(s):  
J. Hoekstra ◽  
H. Yan ◽  
G. Kalonji ◽  
H. Jónsson
Keyword(s):  
Structural Changes ◽  
Elevated Temperatures ◽  
Lattice Mismatch ◽  
Structural Characteristics ◽  
Binding Energies ◽  
Structural Defects ◽  
Interatomic Potentials ◽  
Structural Variations ◽  
Common Neighbor ◽  
Hcp Structure

We present a computer simulation study of thin crystalline multilayers constructed from two fcc solids with differing lattice constants and binding energies. Initially the two solids have the same orientation, and the interface is perpendicular to the common [100] direction. We then minimize the energy of the system at zero temperature or equilibrate it at a finite temperature. Both materials are described by Lennard-Jones interatomic potentials. A novel technique for analyzing local atomic ordering, common neighbor analysis, is used to identify structural characteristics in these systems. As we gradually vary the lattice mismatch between the two solids, several structural changes are observed in the layers of smaller atoms after energy minimization. At a mismatch larger than 14%, the layers transform into the hep structure, while at smaller mismatches extended structural defects are generated. At elevated temperatures, the hcp structure is transformed back to fcc, and the structure defects disappear.

Structure of [(CH3)2NH2]2CoCl4 at elevated temperatures

1999 ◽  
Vol 55 (5) ◽  
pp. 752-757 ◽  
Author(s):  
Amir H. Mahmoudkhani ◽  
Vratislav Langer
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Phase Transitions ◽  
Physical Properties ◽  
Electric Conductivity ◽  
Title Compound ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
The Other ◽  
Cell Parameters

The crystal structure of the title compound, dimethylammonium tetrachlorocobaltate(II), has been determined at four temperatures between 297 and 366 K, in order to investigate possible phase transitions at 313 and 353 K [Kapustianik, Polovinko & Kaluza et al. (1996). Phys. Status Solidi A, 153, 117–122]. We found that there is no significant change either in the hydrogen-bonding network or in the cell parameters, apart from a linear dilatation with temperature. This study reveals that the anomalous variation in electric conductivity and some of the other physical properties of the compound cannot be explained by structural changes.

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