scholarly journals Preparation and Improved Physical Characteristics of Propylene Oxide Rubber Composites

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2150 ◽  
Author(s):  
Natalia Petrova ◽  
Viktoriya Portnyagina ◽  
Vasilii Mukhin ◽  
Ee Shim ◽  
Jin-Ho Cho
Keyword(s):  
Wear Resistance ◽  
Propylene Oxide ◽  
Xrd Analysis ◽  
Low Molecular Weight ◽  
Relaxation Strength ◽  
Rubber Composites ◽  
Positive Effects ◽  
Compression Set ◽  
Siberian Arctic ◽  
Rubber Composite

Sealing rubbers employed in cold climates such as the Siberian Arctic must be able to withstand temperatures as low as −50 °C while still exhibiting specific relaxation, strength, tribological characteristics, and a resistance to aggressive media. Previous investigations of propylene oxide rubber (SKPO, Tg = −73 °C) modified with polytetrafluoroethylene (PTFE) have revealed that, while the rubber composite materials exhibit double the wear resistance compared to unmodified polypropylene oxide rubber, they have poor frost resistance. In the present study, we developed materials based on SKPO and ultrafine PTFE (UPTFE), which can be characterized by its smaller particle size, low molecular weight, high tribo-technical characteristics, and resistance to aggressive media. The properties of the rubber composites were evaluated using the standard methods. The structures of the materials were investigated by electron microscopy and XRD analysis. It was shown that the materials have excellent wear resistance, resistance to aggressive media, compression set, and low-temperature resistance. The addition of UPTFE is preferable to the addition of PTFE because the desired positive effects can be attained with only 0.5–1 parts per hundred parts of rubber (phr) UPTFE while 20 phr PTFE would be necessary.

Fatigue of Unidirectional Cord-Rubber Composites

1999 ◽  
Vol 27 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Y. Liu ◽  
Z. Wan ◽  
Z. Tian ◽  
X. Du ◽  
J. Jiang ◽  
...  
Keyword(s):  
Damage Accumulation ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Constant Load ◽  
Testing System ◽  
Rubber Composites ◽  
Cycle Frequency ◽  
Periodic Loading ◽  
Fatigue Damage Accumulation ◽  
Rubber Composite

Abstract A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out. Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value. The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency. A method for evaluating the fatigue behavior of tires is proposed.

Orthogonal Experiment Analysis of Mechanical Thermal Conductivity on Multi-Component Fillers

2013 ◽  
Vol 753-755 ◽  
pp. 2379-2382
Author(s):  
Shi Meng Xu ◽  
Run Bo Ma ◽  
Jian Hua Du ◽  
Jun Hong Liu ◽  
Qi Jin
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Carbon Black ◽  
Orthogonal Experiment ◽  
Experiment Design ◽  
Rubber Composites ◽  
Orthogonal Experiment Design ◽  
Rubber Composite ◽  
Al Powder ◽  
Experiment Analysis

Filled the N330 carbon black, silica T80 carbon black and Al powder and Fe2O3 magnetic nanoparticles, the rubber composites on multi-component electromagnetic fillers were prepared according to orthogonal experiment analysis, and the preliminary experiment conclusions of the filler prescription designs were given; Based on the experiment design, the mechanical properties and thermal conductivity of the rubber composite were tested, and the testing results were analyzed by using variance analysis. Thus, the paper shows that the effects of N330 on rubber mechanical properties are significant, and the effects of Al powder on the rubber thermal conductivity are significant. Moreover, it is highly emphasized in this paper that the orthogonal experiment design must be carefully explored before the tests are executed.

Modern aspects of the use of drugs of microbial origin

2021 ◽  
Author(s):  
I. O. Pasichna ◽  
V. I. Vdovychenko
Keyword(s):  
Intestinal Microflora ◽  
Antibacterial Properties ◽  
Low Molecular Weight ◽  
Positive Effects ◽  
Microbial Origin ◽  
Transient Nature ◽  
Immunological Effects ◽  
Positive Effect ◽  
Intestinal Microbiocenosis

The recent scientific researches provide evidence of the important role of microbiota for human health. The microbiome is a very complex system, that exists in an equilibrium state and performs multiple functions. The intestinal microflora is disturbed under the influence of iatrogenic factors, and products of microbial origin are used to correct this. The first group of such drugs include probiotics. Their positive effect is associated with immunological and non‑immunological effects. The results of many studies proved the positive effects of probiotics in clinical practice, however publications of recent years outline their low effectiveness and transient nature of the effect, even with prolonged use. Another group of preparations refers to prebiotics, which selectively stimulate the growth of colon microflora. A combination of probiotics and prebiotics, called synbiotics, also in use. Currently, much attention is paid to metabiotics. This group includes various low molecular weight molecules with various chemical manifestations. The components of metabiotics are cellular elements, metabolites and signaling molecules of probiotic cultures. Metabiotics provide the optimal conditions of homeostasis in the contact zone, which are necessary for the normal interaction of the epithelium and microflora, as well as directly affect the physiological functions and biochemical reactions of the macroorganism. The antibacterial properties of metabiotics allow to fight pathogenic and opportunistic flora, without affecting the beneficial microorganisms of the intestine. Creation of targeted metabiotics is a novel promising direction in this area. The possibility of creating a programmed metabiotic drug is considered, depending on the type of disorders of the intestinal microbiocenosis and the peculiarities of the life of specific pathogenic or opportunistic strains.

Effects of Cryogenic Treatment on the Microstructure and Mechanical Properties of High-alloyed Tool Steels

2020 ◽  
Vol 75 (5) ◽  
pp. 73-93
Author(s):  
Alwin Schulz ◽  
Chengsong Cui ◽  
Matthias Steinbacher ◽  
Tuncer Ümit ◽  
Martin Wunde ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Retained Austenite ◽  
Cryogenic Treatment ◽  
Homogeneous Distribution ◽  
Tool Steels ◽  
Positive Effects ◽  
Heat Treated ◽  
Primary Carbides ◽  
Complete Transformation

Abstract In this work, the influence of a cryogenic treatment on the microstructure, mechanical properties and wear resistance of the high-alloyed tool steels X38CrMoV5-3, X153CrMoV12 and ~X190CrVMo20-4 were investigated. Based on tempering curves of the steels, the heat treatment parameters were determined for the mechanical and wear specimens so that the conventionally heat-treated steels and the cryogenically treated steels featured similar hardness. The investigations showed that an almost complete transformation of retained austenite and a more homogeneous distribution of secondary carbides in the microstructure could be achieved by incorporating a cryogenic treatment. However, the cryogenic treatment does not show significantly positive effects on the investigated mechanical properties and wear resistance of the tool steels. The wear resistance of the samples was dominated by primary carbides. The cryogenic treatment would have a positive effect on large tool components with large wall thicknesses in terms of uniform and complete transformation of retained austenite throughout the entire components.

Graft modification in bamboo cellulose nanofibrils: An effective option to improve compatibility and tunable surface energy

2021 ◽  
Author(s):  
Carlos Alejandro Rodríguez-Ramírez ◽  
Alain Dufresne ◽  
Norma Beatriz D'Accorso ◽  
Nancy Garcia
Keyword(s):  
Molecular Weight ◽  
Thermal Properties ◽  
Cellulose Nanofibrils ◽  
Value Added ◽  
Xrd Analysis ◽  
Low Molecular Weight ◽  
Mechanical And Thermal Properties ◽  
Graft Modification ◽  
Effective Option ◽  
20 Nm

Abstract In this work, from an endemic and non-significant value-added bamboo argentine, nanofibrils (CNFs) of 20 nm in width were obtained. These nanofibrils were chemical modified in surface with three simple steps using a noncommercial low molecular weight polylactic acid. The success of modification was confirmed by FTIR, TGA, DSC and XRD analysis. The modified nanofibrils were taken up for changing surface properties in films based on commercial PLA. The results show that dispersive (γ D/S) component of films increase of 34.7 mN/m to 36.1 mN/m after the addition of modified nanofibrils from 2 to 5% in formulation of the films, comparing with a physical blend. Interesting others result in physical, mechanical, and thermal properties of the nanocomposites, were reported.

Surface Modification of Starch and its Application in Rubber Composite with Low Heat Generation and High Fatigue Resistant

2011 ◽  
Vol 194-196 ◽  
pp. 2409-2414
Author(s):  
Qing Hong Fang ◽  
Tian Yu Li ◽  
Na Wang ◽  
Li Jun Jin ◽  
Yue Liang
Keyword(s):  
Surface Modification ◽  
Corn Starch ◽  
Modified Starch ◽  
Organic Solution ◽  
Rubber Composites ◽  
Grafting Reaction ◽  
Rubber Composite ◽  
High Fatigue ◽  
Ether Ester ◽  
Reinforcing Filler

The surface modification of corn starch and the use of modified starch as reinforcing filler partly replaced carbon black in rubber composites were studied. The surface of starch was modified with 3, 4-2H-dihydropyran and maleic anhydride by grafting reaction in organic solution, that is, the process of etherification and the esterification of the starch. The structure of the ether ester starch was investigated by FTIR, SEM. Based on the results of the mechanical and heat building up properties of composite, it is showed that using modified starch as reinforcement filler filled into the rubber partly replaced CB, the characteristics of high flex life and low heat building up for composite can be obtained.

scholarly journals The Preparation and Research on the Electromagnetic Shielding Effectiveness of T-ZnO@Ag/Silicone Rubber Composites

2019 ◽  
Vol 26 (2) ◽  
pp. 205-209 ◽  
Author(s):  
Jingkai NIE ◽  
Guangke WANG ◽  
Dong HOU ◽  
Fu GUO ◽  
Yu HAN
Keyword(s):  
Coating Layer ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Rubber Composites ◽  
Chemical Plating ◽  
Agno3 Solution ◽  
Rubber Composite ◽  
The Matrix ◽  
Micro Structures ◽  
Electromagnetic Shielding Effectiveness

This study first conducted surface modification of Ag-plated Tetrapod-like zinc oxide (T-ZnO) whiskers with the use of dopamine and prepared Ag-plated T-ZnO whiskers (T-ZnO@Ag) by means of chemical plating, in which AgNO3 solutions with different concentrations were used during the preparation. Micro-structures of the prepared T-ZnO@Ag powders were examined to evaluate the effect of AgNO3 concentration on Ag plating performance. Subsequently, conductive Si rubber samples were prepared, the T-ZnO@Ag powders were used as fillers, and the effectiveness of the related electromagnetic shielding was investigated in detail. The results showed that using AgNO3 solution with a concentration of 20 g/L, a continuous Ag coating-layer was observed on the surface of T-ZnO whiskers. It was evident that, when used as fillers, T-ZnO@Ag has a conductive threshold and when the mass fraction of the fillers exceeded 50 %, the T-ZnO@Ag whiskers that were uniformly dispersed in the matrix formed interconnected conductive paths. In this condition, the electromagnetic shielding effectiveness of the prepared T-ZnO@Ag/Si rubber composite reached up 90 dB.

Effects of Micro-Eggshells Filler on Tracking and Erosion Resistance of Silicone Rubber Composites

2020 ◽  
Vol 846 ◽  
pp. 37-41
Author(s):  
Pattarabordee Khaigunha ◽  
Tanakorn Wongwuttanasatian ◽  
Amnart Suksri
Keyword(s):  
Thermal Stability ◽  
Heat Resistance ◽  
Silicone Rubber ◽  
Erosion Resistance ◽  
Rubber Composites ◽  
Surface Tracking ◽  
Rubber Composite ◽  
The Matrix ◽  
Thermal Stability Of ◽  
Inclined Plane Test

This study investigates the effects of micron-sized eggshells filler on resistance to tracking and erosion of silicone rubber composite. Eggshells with particle size from 44 to 53 microns were filled into liquid room temperature vulcanizing (RTV) silicone rubber with 0, 5, 15, 25, and 30 part per hundred of rubber (phr). IEC-60587 inclined plane test (IPT) was employed to appraise the surface tracking resistance. Thermogravimetric analysis was conducted to evaluate its thermal stability. Experimental results revealed an improvement of tracking and erosion resistance due to an addition of eggshells particles. Furthermore, the thermal stability of the composites showed variation in the increasing amount of the filler. The filler indicated that higher thermal stability of eggshells influences the heat resistance of the matrix. An increase of the heat resistance resulted in the ability to slow down tracking growth and erosion in the discharge region.

Toughening, Thermal Stability, Flame Retardancy, and Scratch–Wear Resistance of Polymer–Clay Nanocomposites

2007 ◽  
Vol 60 (7) ◽  
pp. 496 ◽  
Author(s):  
Aravind Dasari ◽  
Szu-Hui Lim ◽  
Zhong-Zhen Yu ◽  
Yiu-Wing Mai
Keyword(s):  
Thermal Stability ◽  
Wear Resistance ◽  
Flame Retardancy ◽  
Interfacial Area ◽  
Barrier Properties ◽  
Clay Nanocomposites ◽  
Positive Effects ◽  
Large Numbers ◽  
Mechanical And Physical Properties ◽  
Wear Response

Addition of a small percent of clay to polymers improves their stiffness, strength, dimensional stability, and thermal, optical, and barrier properties. Improvements are often attributed to the availability of large numbers of clay nanolayers with tremendous interfacial area. Despite the positive effects from the addition of clay, there are unresolved issues, such as embrittlement, thermal stability, flame retardancy, scratch–wear response of the resultant nanocomposites, and/or achieving a balance between different mechanical and physical properties. In this review, we discuss these issues and the approaches that have been adopted in the expectation of resolving and understanding them, with particular emphasis on our recent and current research.

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