scholarly journals The Influence of Nanohydroxyapatite on the Thermal, Mechanical, and Tribological Properties of Polyoxymethylene Nanocomposites

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Kinga Pielichowska ◽  
Dariusz Bieliński ◽  
Michał Dworak ◽  
Ewelina Kilian ◽  
Beata Macherzyńska ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Glass Transition ◽  
Indentation Test ◽  
Degree Of Crystallinity ◽  
Test Results ◽  
Mechanical And Tribological Properties ◽  
Ultrasonic Methods ◽  
Lower Temperature Range ◽  
Lower Temperature

The influence of nanohydroxyapatite on the glass transition region and its activation energy, as well as on the tribological and mechanical properties of polyoxymethylene nanocomposites, was investigated using DMA, TOPEM DSC, nanoindentation, and nondestructive ultrasonic methods. It was found that the glass transition for unmodified POM was in the lower temperature range than in POM/HAp nanocomposites. Moreover,ΔCpand activation energy were larger for POM/HAp nanocomposites. Friction coefficient was higher for POM/HAp nanocomposites in comparison to both POM homopolymer and POM copolymer. Simultaneously, the indentation test results show that microhardness is also higher for POM/HAp nanocomposites than for POM. From ultrasonic investigations it was found that the highest values of both longitudinal and transverse propagation waves and Young’s and shear modulus for POM homopolymer (DH) and POM copolymer T2H and their nanocomposites can be attributed to their higher degree of crystallinity in comparison to UH copolymer. Moreover, for POM/HAp nanocomposites with 5% of HAp, ultrasonic longitudinal wave velocity was almost constant even after 1000000 mechanical loading cycles, evidencing an enhancement of mechanical properties by HAp nanoparticles.

Microstructure, Mechanical and Tribological Properties of the Rapidly Solidified NiAl/Cr(Mo,Dy) Hypoeutectic Alloy

2016 ◽  
Vol 849 ◽  
pp. 590-596 ◽  
Author(s):  
Li Yuan Sheng
Keyword(s):  
Mechanical Properties ◽  
Wear Rate ◽  
Rapid Solidification ◽  
Tribological Properties ◽  
Hypoeutectic Alloy ◽  
Test Results ◽  
Mechanical And Tribological Properties ◽  
Different Temperatures ◽  
Sliding Test ◽  
Rapidly Solidified

The NiAl/Cr (Mo,Dy) hypoeutectic alloy was fabricated by rapid solidification. The microstructure and mechanical properties as well as tribological properties for the alloy at different temperatures were investigated. The results revealed that the rapidly solidified NiAl/Cr (Mo,Dy) hypoeutectic alloy was composed of primary NiAl, fine NiAl/Cr (Mo) eutectic lamella, Ni5Dy phase and Cr7Ni3 precipitate. The compression test showed that the rapid solidification improved the mechanical properties of the NiAl/Cr (Mo,Dy) hypoeutectic alloy obviously. The dry sliding test results showed that alloy had excellent tribological properties at about 1073 K, which obtained wear rate of 4.9 10-14m3/m·N and friction coefficient of 0.16 μ. The excellent tribological properties at high temperature may be attributed to the continuous and intact protecting lubricant film which was composed of amorphous, Cr2O3 and Al2O3 nanoparticles. Between 700 K to 900 K, the alloy demonstrated bad tribological properties, especially the high wear rate, which may be ascribed to the softening of NiAl and Cr (Mo) phases.

CONNECTION BETWEEN STRUCTURAL CHANGES OF IRRIADIATED POLYETHER ETHER KETONE AND MECHANICAL PROPERTIES

Tribologia ◽  
2018 ◽  
Vol 278 (2) ◽  
pp. 95-101
Author(s):  
Aneta NIEMIEC
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Structural Changes ◽  
Radiation Energy ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polyether Ether Ketone ◽  
Ether Ketone ◽  
The Impact ◽  
The Degree Of Crystallinity

The article presents the results of research on the impact of structural changes in polyether ether ketone (PEEK) on its mechanical properties. The polymer was exposed to gamma radiation at a dose of 50 and 150 kGy, and the radiation energy was 4 MeV. Changes in the degree of crystallinity and the related changes in the glass transition and melting temperature for the polymer were determined by differential scanning calorimetry (DSC). Mechanical properties were determined using the micro-mentoring method. The tests showed a change in the degree of crystallinity in the range of several degrees and a significant increase in the glass transition temperature. In terms of mechanical properties, the reduction of hardness and Young’s modulus was observed. Observed changes, especially in terms of changes in the structure of the polymer under the influence of radiation, are difficult to explain, which requires conducting further research, especially in the range of irradiation parameters used. Further research is important because PEEK is used in many fields, especially in conditions conducive to corrosion and the influence of radiation.

Tribological properties of bismaleimide reinforced with Si-containing benzoxazine monomer

2021 ◽  
pp. 095400832199079
Author(s):  
Ju-xiang Yang ◽  
Yuan Jia ◽  
Pengna Li ◽  
Ping Sun
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Glass Transition ◽  
Thermal Properties ◽  
Tribological Properties ◽  
Silane Coupling Agent ◽  
Mechanical Performance ◽  
The Novel ◽  
Mechanical And Tribological Properties ◽  
Silane Coupling

To improve the mechanical and tribological properties of bismaleimide (BMI) resin, a novel Si-containing benzoxazine (Si-BOZ) monomer was synthesized using a solvent process and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane as a silane coupling agent. The novel Si-BOZ monomer was subsequently blended with BMI to prepare Si-BOZ/BMI polymer alloys. Furthermore, the effect of Si-BOZ content on the mechanical, tribological, and thermal properties of Si-BOZ/BMI alloys was investigated. The results revealed that the addition of Si-BOZ to BMI improved the mechanical properties and wear resistance of Si-BOZ/BMI; moreover, the glass transition temperature of cured Si-BOZ/BMI alloys was lower than that of pure BMI resin. These results confirmed that the increase in wear resistance of Si-BOZ/BMI alloys can be attributed to the increase in thermal resistance and improvement in mechanical performance owing to the addition of Si-BOZ.

scholarly journals Influence of inert gases on the catalytic oxidation of SO2

1970 ◽  
Vol 48 (8) ◽  
pp. 1175-1182 ◽  
Author(s):  
A. A. Yeramian ◽  
P. L. Silveston ◽  
R. R. Hudgins
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Sulfur Dioxide ◽  
Gas Phase ◽  
Reaction Rate ◽  
Independent Study ◽  
Inert Gases ◽  
Momentum Exchange ◽  
Lower Temperature Range ◽  
Lower Temperature

A study was made of the influence of diluent gases on the reaction rate and activation energy of the oxidation of sulfur dioxide over vanadium pentoxide catalyst, an effect noted by Baron, Manning, and Johnstone in 1952. Results confirmed the occurrence of the effect in a still lower temperature range (350–470 °C). Using non-adsorbing gases, helium and argon, the effect was demonstrated to be free from chemisorption of the diluents.Data on activation energy vs. molecular weight of the gas phase, using helium and argon, were in qualitative agreement with predictions based on a momentum-exchange model of Baron etal. However, comparison of rates obtained with argon (monatomic) and nitrogen (diatomic) as diluents, combined with independent study of the rate controlling steps, casts doubt on the adequacy of the explanation offered by Baron etal.

scholarly journals The effect of flame straightening on the microstructure and mechanical properties of different strength steels

2021 ◽  
Author(s):  
László Gyura ◽  
Marcell Gáspár ◽  
András Balogh
Keyword(s):  
Mechanical Properties ◽  
High Sensitivity ◽  
High Strength ◽  
Water Cooling ◽  
Experimental Conditions ◽  
Physical Simulations ◽  
Lower Temperature Range ◽  
Lower Temperature ◽  
Subcritical Temperature ◽  
Supercritical Temperature

AbstractIn many cases, flame straightening is unavoidable after welding for the reduction of deformation. Due to the not very concentrated heat source, the process can cause significant changes in the microstructure, especially in high strength and wear-resistant steels. Due to their different physical properties, the effects vary depending on the flammable gases (acetylene, propane). The situation is complicated by the fact that the manual technology carries a risk of overheating, which can have detrimental effects on the mechanical properties. During our experiments, three steels are investigated (S355J2 + N, XAR400, S960QL). The thermal cycles for the physical simulations were determined by thermocouple measurement during real experimental conditions. Three peak temperatures (1000 °C, 800 °C and 675 °C) and two types of industrial cooling conditions (air and water cooling) were studied. The samples were examined by optical microscopy tests, hardness testing and Charpy V-notch impact tests. During straightening the XAR400 showed high sensitivity to softening even in the lower temperature range, while hardening occurred in the S960QL steel at a higher peak temperature values during water cooling. The inter- and supercritical temperature should be avoided in all steels; however, the subcritical temperature can be beneficial to the toughness properties of the S960QL and XAR400.

Autothermal Reforming of Propane over Hydrotalcite-Like Catalysts Containing Promotor

2007 ◽  
Vol 7 (11) ◽  
pp. 4009-4012 ◽  
Author(s):  
You-Soon Lim ◽  
Dong-Ju Moon ◽  
Nam-Cook Park ◽  
Jae-Soon Shin ◽  
Jong-Ho Kim ◽  
...  
Keyword(s):  
Noble Metals ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
Test Results ◽  
Low Carbon ◽  
Temperature Range ◽  
Reaction Test ◽  
Lower Temperature Range ◽  
Lower Temperature ◽  
Co Precipitation

Hydrotalcite-like catalysts were synthesized by co-precipitation and then these were promoted by the addition of noble metals, alkaline earth metals and ceria. Reaction tests were conducted using a feed of H2O/C/O2 = 3/1/0.37 at a temperature range from 300 °C to 700 °C. Catalysts were characterized by XRD, TEM, FESEM, TPR, and BET. Reaction test results confirmed an enhancement of the catalytic activity of the promotor-modified catalysts due to low carbon deposition. Among the alkaline earth metals tested, those with larger atomic number exhibited higher activity at a lower temperature range.

scholarly journals Study of Raw and Recycled Polyethylene Terephthalate by Meaning of TGA and Computer Simulation

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Bouzid Latifa ◽  
Fouddad Fatma Zohra ◽  
Hiadsi Said
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Computer Simulation ◽  
Glass Transition ◽  
Polyethylene Terephthalate ◽  
Heating Rates ◽  
Distributed Activation Energy Model ◽  
Pyrolysis Method ◽  
Recycled Polyethylene ◽  
Mathematical Equations

The pyrolysis method of both raw and recycled polyethylene terephthalate was studied using the nonisothermal thermogravimetric analysis (TGA) at different five heating rates (10, 15, 20, 25, and 30 K/min) for each element. Without using any mathematical equations, the kinetic parameters of polyethylene terephthalate pyrolysis were obtained by applying the modified distributed activation energy model (DAEM). Furthermore, the glass transition temperature (Tg) of polyethylene terephthalate was simulated using the computer simulation with different methods. The effect of energy in the Tg process was enhanced. The mechanical properties of polyethylene terephthalate were computed. Our simulated values were compared with available data in literature.

scholarly journals INFLUENCE OF SURFACE CHEMISTRY OF THE FILLER AND THERMAL MODIFICATION OF BNKS-40 / PVC COMPOSITIONS ON THE VIBRO-ABSORBING PROPERTIES OF THE MATERIAL

2019 ◽  
Vol 62 (9) ◽  
pp. 66-72
Author(s):  
Irina A. Mansurova ◽  
Ivan B. Shilov ◽  
Andrey A. Burkov ◽  
Ilya Yu. Koshkin ◽  
Yuri V. Yurkin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Surface Chemistry ◽  
Mechanical Analysis ◽  
Thermal Modification ◽  
Transition Range ◽  
Vibration Absorption ◽  
Temperature Range ◽  
Rise Rate ◽  
Lower Temperature Range ◽  
Lower Temperature

The study looks into the effect of a silicic acid filler's (SAF) surface chemistry and thermal modification of BNKS-40/PVC-based (80:20) compounds upon material's vibration-absorbing properties. The thermal analysis (TGA and DTA, Shimadzu analyzer, the temperature rise rate - 10 ° С/min), IR spectroscopy (Infralume FT-08, MFTIR) demonstrated, that adsorption of organosilane bis(3triethoxysilylpropyl)disulfide (TESPD) and the following silanization of Newsil 1165МР (145 ° С, 5 min) occur more readily on the surface of the SAF, dried in mild conditions (70 ° С) in advance. Dehydration of the SAF surface contributes to an increase in the proportion of organosilane physically associated with its surface (2.4 times), rather than chemically (1.1 times). SAF silanization results in the decrease in the compounds' Mooney viscosity (MB 1+4, 100 ° С, CU) and the higher content of free TESPD, the more pronounced the decrease is. The dynamic mechanical analysis (Netzsch DMA 242, in the temperature range from -60 to +60 °С and the frequency range from 0.1 to 10 Hz) demonstrated that, free TESPD plasticized the polymer matrix, increasing TanD as well as shifting the peak of mechanical losses into the lower temperature range. In this case, the effective temperature range of vibration absorption (ETRVA, where TanD ≥ 0.3) is somewhat narrowed in comparison with the compound containing the initial SAF. Thermal modification of BNKS-40/PVC compounds (120 ° С, 4 h) is accompanied by ETRVA expansion in the elastomer glass transition range, as well as in the glass transition temperature of the elastomer-thermoplast transition range.  This fact is due to the diffusion of polymers in the filler-elastomer/thermoplast- and the elastomer-thermoplast inter-phase zones. Thermal modification is effective with compounds containing silanized filler with the least amount of free TESPD.

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