Abrasion of Butyl Rubber

1956 ◽  
Vol 29 (2) ◽  
pp. 333-354
Author(s):  
R. L. Zapp
Keyword(s):  
Dynamic Modulus ◽  
Abrasion Resistance ◽  
Surface Friction ◽  
Cross Linking ◽  
Dynamic Hardness ◽  
Laboratory Results ◽  
Rupture Energy ◽  
Abrasive Surface ◽  
Wear Tests ◽  
Selection Of

Abstract By using the Lambourn abrader, a concept of abrasion has been proposed that fits the performance of a wide variety of compounds. The ability of this type of machine to give varying degrees of slip and braking forces has aided in the selection of the proper conditions for abrasion studies. By using a small tread pattern on the sample wheel, laboratory results are brought into closer agreement with actual road wear tests. The work of Schallamach and the analysis of abrasion by a needle abrader have been extended to an abrasive surface. To the considerations of compound strength and surface friction or traction has been added the consideration of dynamic hardness. The abrasion of rubber has then been related to a ratio of dynamic modulus over rupture energy. Thus if a compound is made dynamically softer or more conformable without a sacrifice of its resistance to rupture, a superior abrading tread will result. In simple terms, what is needed for best abrasion resistance is the softest toughest material. Butyl owes its comparable or superior abrasion resistance (compared to other rubbers) to the fact that its vulcanizates are dynamically softer. The heat treatment of Butyl carbon black mixtures produces vulcanizates that are still softer in relation to their rupture energy. This is the sole advantage of such a mixing procedure. Other polymer and compounding variables that tend to decrease the ratio of dynamic hardness to rupture energy improve abrasion resistance. These changes include increasing the molecular weight of the polymer and reducing somewhat the unsaturation. A certain quantity of plasticizer to increase softness and a reduction of the state of cure have been shown to be beneficial. The latter change produced by a reduction of the amount of sulfur in the compound, which limits the extent of cross-linking, has resulted in distinctly superior tire treads.

Correlation between Laboratory and Road Rubber Wear Tests

1995 ◽  
Vol 68 (5) ◽  
pp. 804-814 ◽  
Author(s):  
V. Krishnan ◽  
R. Ramakrishnan ◽  
J. A. Donovan
Keyword(s):  
Silicon Carbide ◽  
Wear Resistance ◽  
Ambient Temperature ◽  
Dynamic Modulus ◽  
Laboratory Testing ◽  
Grinding Wheels ◽  
Rubber Compounds ◽  
Rupture Energy ◽  
Wear Tests

Abstract The wear resistance ranking of three rubber compounds A, G and K measured in the laboratory at medium to high slip on sharp silicon carbide (SiC) grinding wheels was similar to that determined by road tests at Pecos, Texas. The wear resistance ranking of the three compounds changed on blunt alumina grinding wheels compared to wear resistance rankings on sharp SiC grinding wheels. The change was most probably due to a change of mechanism from mainly cutting on sharp surfaces to predominantly fatigue on blunt surfaces. For these three compounds a change in the ambient temperature from 23 to 75°C during laboratory testing had no effect on the wear resistance ranking. The wear of the rubber compounds on the abrasive grinding wheels and during road tests followed Zapp's relation in which the wear is proportional to the ratio of dynamic modulus to rupture energy.

Priority Selection of Weak Gel Flooding Formula on Heterogeneous Reservoir

2014 ◽  
Vol 1073-1076 ◽  
pp. 2248-2251
Author(s):  
Wen Xiang Wu ◽  
Xin Song ◽  
Yue Fu ◽  
Peng Fei Yuan
Keyword(s):  
Gelation Time ◽  
High Viscosity ◽  
Development Stage ◽  
Water Flooding ◽  
Cross Linking ◽  
Heterogeneous Reservoirs ◽  
Weak Gel ◽  
Core Displacement ◽  
Selection Of ◽  
Gel System

Nowadays, most of the oilfields have been entered later development stage, it is difficult for reservoirs to depend on water flooding technology to improve recovery factor enormously. To satisfy deep flooding demand on heterogeneous reservoirs, the weak gel system is developed in the lab. Due to the mixture of organic chromium and HAPM, forming the organic weak gel system. HPAM concentration is from 1300mg/l to 1500mg/l and from 150mg/l to 210mg/l for cross-linking agent, the weak gel system formed stably with the high viscosity which is above 10000mp·s and moderate gelation time is from 45h to 130h.The best formula was selected with HPAM concentration 1500mg/l, and cross-linking agent concentration 210mg/l.The core displacement experiment shows the weak gel system has a well flooding effect on heterogeneous reservoirs, and its recovery rate increases 16.2%。

Textile Performance Properties of Cotton Fabric Treated with Selected Flame-Retarding Finishes

1977 ◽  
Vol 47 (5) ◽  
pp. 365-371 ◽  
Author(s):  
Stanley P. Rowland ◽  
John S. Mason
Keyword(s):  
Cotton Fabric ◽  
Abrasion Resistance ◽  
Breaking Strength ◽  
Superior Performance ◽  
Disodium Hydrogen Phosphate ◽  
Performance Properties ◽  
Different Types ◽  
The Individual ◽  
Medium Weight ◽  
Selection Of

Seven different types of flame-retarding finishes were applied to light-to-medium weight cotton fabric at add-ons appropriate to pass the DOC FF 3–71 test. The finishes studied were based on tetrakis(hydroxymethyl)phosphonium chloride (THPC), neutralized THPC (THPOH), Fyrol 76, and Pyrovatex CP. The specific finishes were: THPOH-NH3, THPOH-urea-trimethylolmelamine, Proban (THPC-urea precondensate)-NH3, THPC-urea-disodium hydrogen phosphate, Fyrol 76, Fyrol 76-N-methylolacrylamide, and Pyrovatex CP-methylolmelamine. Textile performance properties are reported as a function of add-on of each type of finish; strengths and abrasion resistance of the finished fabrics are considered and discussed as a function of resilience. General trends of decreasing strength and abrasion resistance with increasing resilience were observed for these flame-retardant fabrics. Within this trend there is latitude for selection of finishes that will provide superior performance in the individual textile property such as abrasion resistance, breaking strength, and tearing strength.

Model-based selection of the degree of cross-linking of cation exchanger resins for an optimised separation of monosaccharides

2020 ◽  
Vol 1610 ◽  
pp. 460565
Author(s):  
Martin Leipnitz ◽  
Andreas Biselli ◽  
Marcel Merfeld ◽  
Niklas Scholl ◽  
Andreas Jupke
Keyword(s):  
Cation Exchanger ◽  
Cross Linking ◽  
Model Based ◽  
Selection Of

Biological control of ticks

Parasitology ◽  
2004 ◽  
Vol 129 (S1) ◽  
pp. S389-S403 ◽  
Author(s):  
M. SAMISH ◽  
H. GINSBERG ◽  
I. GLAZER
Keyword(s):  
Biological Control ◽  
Entomopathogenic Nematodes ◽  
Biocontrol Agents ◽  
Parasitoid Wasps ◽  
Natural Conditions ◽  
Potential Value ◽  
Considerable Research ◽  
Production Strategies ◽  
Laboratory Results ◽  
Selection Of

Ticks have numerous natural enemies, but only a few species have been evaluated as tick biocontrol agents (BCAs). Some laboratory results suggest that several bacteria are pathogenic to ticks, but their mode of action and their potential value as biocontrol agents remain to be determined. The most promising entomopathogenic fungi appear to be Metarhizium anisopliae and Beauveria bassiana, strains of which are already commercially available for the control of some pests. Development of effective formulations is critical for tick management. Entomopathogenic nematodes that are pathogenic to ticks can potentially control ticks, but improved formulations and selection of novel nematode strains are needed. Parasitoid wasps of the genus Ixodiphagus do not typically control ticks under natural conditions, but inundative releases show potential value. Most predators of ticks are generalists, with a limited potential for tick management (one possible exception is oxpeckers in Africa). Biological control is likely to play a substantial role in future IPM programmes for ticks because of the diversity of taxa that show high potential as tick BCAs. Considerable research is required to select appropriate strains, develop them as BCAs, establish their effectiveness, and devise production strategies to bring them to practical use.

scholarly journals Chemical Cross-Linking Stabilizes Native-Like HIV-1 Envelope Glycoprotein Trimer Antigens

2015 ◽  
Vol 90 (2) ◽  
pp. 813-828 ◽  
Author(s):  
Torben Schiffner ◽  
Natalia de Val ◽  
Rebecca A. Russell ◽  
Steven W. de Taeye ◽  
Alba Torrents de la Peña ◽  
...  
Keyword(s):  
Envelope Glycoprotein ◽  
Morphological Characteristics ◽  
Neutralizing Antibody ◽  
Structural Instability ◽  
Cross Linking ◽  
Public Health Importance ◽  
Protective Antibodies ◽  
Hiv 1 ◽  
Chemical Cross Linking ◽  
Selection Of

ABSTRACTMajor neutralizing antibody immune evasion strategies of the HIV-1 envelope glycoprotein (Env) trimer include conformational and structural instability. Stabilized soluble trimers such as BG505 SOSIP.664 mimic the structure of virion-associated Env but nevertheless sample different conformational states. Here we demonstrate that treating BG505 SOSIP.664 trimers with glutaraldehyde or a heterobifunctional cross-linker introduces additional stability with relatively modest effects on antigenicity. Thus, most broadly neutralizing antibody (bNAb) epitopes were preserved after cross-linking, whereas the binding of most weakly or nonneutralizing antibodies (non-NAb) was reduced. Cross-linking stabilized all Env conformers present within a mixed population, and individual conformers could be isolated by bNAb affinity chromatography. Both positive selection of cross-linked conformers using the quaternary epitope-specific bNAbs PGT145, PGT151, and 3BC315 and negative selection with non-NAbs against the V3 region enriched for trimer populations with improved antigenicity for bNAbs. Similar results were obtained using the clade B B41 SOSIP.664 trimer. The cross-linking method may, therefore, be useful for countering the natural conformational heterogeneity of some HIV-1 Env proteins and, by extrapolation, also vaccine immunogens from other pathogens.IMPORTANCEThe development of a vaccine to induce protective antibodies against HIV-1 is of primary public health importance. Recent advances in immunogen design have provided soluble recombinant envelope glycoprotein trimers with near-native morphology and antigenicity. However, these trimers are conformationally flexible, potentially reducing B-cell recognition of neutralizing antibody epitopes. Here we show that chemical cross-linking increases trimer stability, reducing binding of nonneutralizing antibodies while largely maintaining neutralizing antibody binding. Cross-linking followed by positive or negative antibody affinity selection of individual stable conformational variants further improved the antigenic and morphological characteristics of the trimers. This approach may be generally applicable to HIV-1 Env and also to other conformationally flexible pathogen antigens.

A Coating Evaluation Testing Program★

CORROSION ◽  
1958 ◽  
Vol 14 (12) ◽  
pp. 18-24 ◽  
Author(s):  
E. R. ALLEN
Keyword(s):  
Field Performance ◽  
Service Performance ◽  
New Materials ◽  
Test Program ◽  
Test Procedures ◽  
Controlled System ◽  
Field Service ◽  
Laboratory Results ◽  
Laboratory Procedures ◽  
Selection Of

Abstract A program to test and evaluate external pipeline coatings is described. When this program was started ten years ago, many methods and procedures then in use did not give all of the information desired. Field burial tests are lengthly and because of the variable conditions which govern results can neither be controlled nor evaluated with any precision. Only laboratory type tests are suitable for a closely controlled system of coating evaluation. Laboratory results must be correlated with field service performance. This test program was in three phases: First, laboratory procedures and apparatus were developed. Second, commonly used coatings were tested ana laboratory results correlated with field performance data. Third, new materials were tested and their performance compared with coatings in common use. Laboratory and field test procedures and apparatus are described. A discussion on the application of test data to selection of pipeline coatings is included. 2.1.2

Improved wear properties of high energy ion-implanted polycarbonate

1995 ◽  
Vol 10 (1) ◽  
pp. 190-201 ◽  
Author(s):  
G.R. Rao ◽  
E.H. Lee ◽  
R. Bhattacharya ◽  
A.W. McCormick
Keyword(s):  
Energy Transfer ◽  
Lower Energy ◽  
Sliding Wear ◽  
Ion Irradiation ◽  
Surface Hardness ◽  
High Energy ◽  
Cross Linking ◽  
Wear Properties ◽  
Hardness Values ◽  
Wear Tests

Polycarbonate (LexanTM) (PC) was implanted with 2 MeV B+ and O+ ions separately to fluences of 5 × 1017, 1 × 1018, and 5 × 1018 ions/m2, and characterized for changes in surface hardness and tribological properties. Results of tests showed that hardness values of all implanted specimens increased over those of the unirradiated material, and the O+ implantation was more effective in improving hardness for a given fluence than the B+ implantation. Reciprocating sliding wear tests using a nylon ball counterface yielded significant improvements for all implanted specimens except for the 5 × 1017 ions/m2 B+-implanted PC. Wear tests conducted with a 52100 steel ball yielded significant improvements for the highest fluence of 5 × 1018 ions/m2 for both ions, but not for the two lower fluences. The improvements in properties were related to Linear Energy Transfer (LET) mechanisms, where it was shown that the O+ implantation caused greater ionization, thereby greater cross-linking at the surface corresponding to much better improvements in properties. The results were also compared with a previous study on PC using 200 keV B+ ions. The present study indicates that high energy ion irradiation produces thicker, more cross-linked, harder, and more wear-resistant surfaces on polymers and thereby improves properties to a greater extent and more efficiently than lower energy ion implantation.

scholarly journals IMMUNE THERAPY INFLUENCE ON a-DEFENSIN LEVEL IN PERIPHERAL BLOOD NEUTROPHILES IN PYODERMIA PATIENTS

2010 ◽  
Vol 7 (6) ◽  
pp. 25-30
Author(s):  
E A Tsyvkina ◽  
E S Fedenko ◽  
A S Budikhina ◽  
B V Pinegin
Keyword(s):  
Peripheral Blood ◽  
Immune Therapy ◽  
Muramyl Dipeptide ◽  
Complex Treatment ◽  
Treatment Results ◽  
Level Increase ◽  
Healthy Donors ◽  
Laboratory Results ◽  
Definition Of ◽  
Selection Of

Background. The purpose was to investigate a-defensin levels in neutrophiles of pyodermia patients in comparison with healthy donors, to estimate clinical efficiency of glucosaminyl muramyl dipeptide (Licopid) and its influence on a-defensin levels. Materials and method. 31 patients with pyodermia and 17 healthy donors were investigated. Intracellular a-defensin levels in neutrophiles in the peripheral blood were estimated by flow cytometry with mouse anti-NPantibodies (Hy cult biotechnology). All patients with pyodermia were treated with Licopid 10 mg once a day within 10 days. Clinical and laboratory results were measured after 7-0 days course of treatment and one month after treatment. Results. The a-defensin level in patients with pyodermia was reduced in comparison with healthy donors. Immune therapy with licopid 10 mg once a day as a complex treatment lead to a-defensin level increase in leukocytes of peripheral blood. Conclusion. The treatment with licopid 10 mg a day lead to prolonged remission and to increase of endocellular a-defensin level. Definition of a-defensin levels can be useful for advisability and for selection of immune therapy in pyodermia patients. Thus, a decrease of a-defensin levels in pyodermia patients, possibly, is a marker of the chronic bacterial inflammation.

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