scholarly journals Fabrication and Characterization of Isotropic and Anisotropic Magnetorheological Elastomers, Based on Silicone Rubber and Carbonyl Iron Microparticles

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1343 ◽  
Author(s):  
Jesús Puente-Córdova ◽  
M. Reyes-Melo ◽  
Luis Palacios-Pineda ◽  
Imperio Martínez-Perales ◽  
Oscar Martínez-Romero ◽  
...  
Keyword(s):  
Experimental Data ◽  
Silicone Rubber ◽  
Carbonyl Iron ◽  
Loss Modulus ◽  
Rubber Matrix ◽  
Zener Model ◽  
Magnetorheological Elastomers ◽  
In Series ◽  
Fractional Zener Model

This article focuses on studying the rheological behavior of isotropic and anisotropic magnetorheological elastomers (MREs), made of carbonyl iron microparticles dispersed into a silicone–rubber matrix by considering 20 and 30 wt % of microparticles. Sample sets were prepared for each composition, with and without the application of an external magnetic field. Experimental measurements of the material rheology behavior were carried out by a shear oscillatory rheometer at constant temperature, to determine both the shear storage modulus (G′) and shear loss modulus (G′′) for all characterized samples. Then, experimental data collected from the isotropic and the anisotropic material samples were used to plot the Cole-Cole diagrams to quantify the interfacial adhesion between carbonyl iron microparticles and the silicone-rubber matrix. Furthermore, the Fractional Zener Model (FZM) with two spring-pots in series is used for quantitative analysis of collected experimental data.

Performance of Magnetorheological Elastomer Based Silicone/SAIB

2018 ◽  
Vol 772 ◽  
pp. 61-65
Author(s):  
Muntaz Hana Ahmad Khairi ◽  
Saiful Amri Mazlan ◽  
Ubaidillah ◽  
Siti Aishah Abdul Aziz ◽  
Norhiwani Mohd Hapipi
Keyword(s):  
Rheological Properties ◽  
Silicone Rubber ◽  
Carbonyl Iron ◽  
Excitation Frequency ◽  
Rubber Matrix ◽  
Iron Particles ◽  
Magnetorheological Elastomer ◽  
Magnetorheological Elastomers ◽  
Mr Effect ◽  
Strain Dependent

This study introduces a sucrose acetate isobutyrate (SAIB) as an additive of magnetorheological elastomers (MREs) to be added in silicone rubber matrix and carbonyl iron particles (CIPs) as their filler. The CIPs were fixed at 60 wt% and two types of MREs sample were fabricated which are isotropic and anisotropic. Rheological properties related to shear storage modulus were measured using a rheometer (MCR 302, Anton Paar). The experimental results demonstrated that the magnetorheological (MR) effect of anisotropic MREs-based Silicone/SAIB was 126 % as compared to isotropic MREs-based Silicone/SAIB, 64%. The fabricated MREs samples were frequency and strain dependent. The relative MR effect for both samples showed decreasing trend with the increment of strain amplitude and excitation frequency.

scholarly journals Simultaneous Characterization of Relaxation, Creep, Dissipation, and Hysteresis by Fractional-Order Constitutive Models

2021 ◽  
Vol 5 (2) ◽  
pp. 36
Author(s):  
Jun-Sheng Duan ◽  
Di-Chen Hu ◽  
Yang-Quan Chen
Keyword(s):  
Constitutive Model ◽  
Storage Modulus ◽  
Loss Factor ◽  
Creep Compliance ◽  
Loss Modulus ◽  
Constitutive Models ◽  
Stationary Points ◽  
Logarithmic Scale ◽  
Zener Model ◽  
Fractional Zener Model

We considered relaxation, creep, dissipation, and hysteresis resulting from a six-parameter fractional constitutive model and its particular cases. The storage modulus, loss modulus, and loss factor, as well as their characteristics based on the thermodynamic requirements, were investigated. It was proved that for the fractional Maxwell model, the storage modulus increases monotonically, while the loss modulus has symmetrical peaks for its curve against the logarithmic scale log(ω), and for the fractional Zener model, the storage modulus monotonically increases while the loss modulus and the loss factor have symmetrical peaks for their curves against the logarithmic scale log(ω). The peak values and corresponding stationary points were analytically given. The relaxation modulus and the creep compliance for the six-parameter fractional constitutive model were given in terms of the Mittag–Leffler functions. Finally, the stress–strain hysteresis loops were simulated by making use of the derived creep compliance for the fractional Zener model. These results show that the fractional constitutive models could characterize the relaxation, creep, dissipation, and hysteresis phenomena of viscoelastic bodies, and fractional orders α and β could be used to model real-world physical properties well.

Torsional characterization of ropes used offshore

2008 ◽  
Vol 43 (2) ◽  
pp. 121-139 ◽  
Author(s):  
I M L Ridge
Keyword(s):  
Experimental Data ◽  
Torsional Response ◽  
In Series ◽  
Different Levels

The first part of this paper presents a general discussion of the various problems which must be addressed when combining different ropes in series or, in some cases, in using a rope in conditions where it is rotationally unrestrained. The paper will pay particular attention to the various classes of rope used in the offshore environment and their main torsional characteristics. In the second part, equipment is shown which is suitable for the measurement of the torsional response of various rope constructions at different levels of twist. Experimental data are presented for a variety of rope constructions at sizes comparable with those used in offshore applications. Comparison is made with data obtained in similar previous studies but with smaller‐diameter ropes.

Modeling and Verification of Relaxation Behavior for Magnetorheological Elastomers with Applied Magnetic Field

2017 ◽  
Vol 730 ◽  
pp. 527-532 ◽  
Author(s):  
Guo Jun Yu ◽  
Xiao Guo Lin ◽  
Fei Guo
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Shear Strain ◽  
Magnetic Field Strength ◽  
Relaxation Modulus ◽  
Relaxation Behavior ◽  
Rubber Matrix ◽  
Magnetorheological Elastomers ◽  
The Magnetic Field

In this paper, on the basis of the viscoelastic fractional derivative model, Mittag-Leffler function is applied to deduce the expression of stress relaxation modulus for magnetorheological elastomers according to its form and main properties. Furthermore, the relaxation modulus for polyurethane rubber matrix cured magnetorheological elastomers at different applied magnetic fields and shear strains is tested by rheometer. The results indicate that magnetorheological elastomers exhibit obvious relaxation behavior and the magnetic field strength and shear strain exert significant influence on the relaxation behavior: the relaxation modulus of magnetorheological elastomers increases with the magnetic field strength but decreases with the shear strain. Besides, the model agrees well with the experimental data which indicates that the model is suitable for characterization of relaxation behavior for magnetorheological elastomers.

scholarly journals Influence of Additives on Thermal Properties and Morphological of Magnetorheological Elastomer

2019 ◽  
Vol 7 (4.14) ◽  
pp. 529
Author(s):  
Ku Zarina Ku Ahmad ◽  
MHA Khairi ◽  
SA Mazlan
Keyword(s):  
Natural Rubber ◽  
Smart Materials ◽  
Carbonyl Iron ◽  
Magnetic Particles ◽  
Base Material ◽  
Rubber Matrix ◽  
Iron Particles ◽  
Soft Magnetic ◽  
Magnetorheological Elastomers ◽  
Roll Mill

Magnetorheological elastomers (MREs) are categorized as part of the smart materials class whose rheological properties can be altered under the influence of a magnetic field. MREs are fabricated by embedding soft magnetic particles such as carbonyl iron particles (CIPs) in a rubber matrix such as silicone and natural rubber. In this project, epoxidized natural rubber (ENR-50) is used as a base material with carbonyl iron particles. Sucrose Acetate Isobutyrate (SAIB) ester is added to the formulation to improve the viscosity and enhance the MRE properties. The isotropic MRE is fabricated using two roll mill and a compression mould. Various tests comprise mechanical, morphology, thermal and magnetic tests were conducted for MRE characterization purpose. The results showed that the addition of SAIB on the MRE had reduced 53% of viscosity in the rubber matrix compared to non-ester based MRE. Dispersion of magnetic particles is improved by the addition of ester as observed through Field Emission Scanning Electron Microscope (FESEM). Additionally, the thermal stability was also improved. Tensile strength of MRE consisting SAIB ester achieved maximum strength of 12.3 MPa and an elongation of 620% compared to non-ester based MRE.  

Self-heating and dynamic mechanical behavior of silicone rubber composite filled with carbonyl iron particles under cyclic compressive loading

2021 ◽  
pp. 002199832110370
Author(s):  
Tran Huu Nam ◽  
Iva Petríková ◽  
Bohdana Marvalová ◽  
Mohammad Yousef Hdaib
Keyword(s):  
Silicone Rubber ◽  
Carbonyl Iron ◽  
Loss Modulus ◽  
Compressive Loading ◽  
The Self ◽  
Iron Particles ◽  
Dynamic Mechanical ◽  
Self Heating ◽  
Dynamic Mechanical Behavior ◽  
Rubber Composite

Self-heating and dynamic mechanical behavior of isotropic silicone rubber composite (SRC) filled with micro-sized carbonyl iron particles (CIPs) subjected to cyclic compressive loading have been studied. Effects of pre-strains from 5 to 20%, strain amplitudes from 1 to 5%, and excitation frequencies from 10 to 50 Hz on the self-heating and dynamic mechanical response of the isotropic SRC were investigated. The self-heating temperatures were measured on the surface and at the center of cylindrical SRC specimens. The self-heating temperatures of the isotropic SRC samples showed a fast increase in an initial transient stage and the following isothermal stage. The temperature distribution in the isotropic SRC specimens was non-homogeneous and the temperature decreased from the center to sample edges. The self-heating temperatures of the isotropic SRC increased gradually with raising the strain amplitude and frequency. However, the difference between the internal and surface temperatures was slight for low strain amplitudes and frequencies, while it was significant for high strain amplitudes and frequencies. The temperatures of the isotropic SRC boosted rapidly with increasing the pre-strain to 10% and thereafter gained slightly. Although the isotropic SRC dynamic moduli reduced with the rise of the strain amplitude, they enhanced with increasing the pre-strain and frequency. Besides, the storage modulus of the isotropic SRC varied slightly with time, while the loss modulus reduced markedly especially at the initial period. The decrease in the loss modulus of the isotropic SRC under cyclic compressive loading is attributed to its self-heating temperature rise. A finite element simulation of the heat transfer in the SRC cylinder was conducted. The calculated temperatures in the SRC cylinder were in good agreement with the measured ones at different strain amplitudes and frequencies.

Comparison of Aerobic and Anoxic-Aerobic Digestion of Waste Activated Sludge

1985 ◽  
Vol 17 (8) ◽  
pp. 1475-1478 ◽  
Author(s):  
A P. C. Warner ◽  
G. A. Ekama ◽  
G v. R. Marais
Keyword(s):  
Experimental Data ◽  
Activated Sludge ◽  
Waste Activated Sludge ◽  
Activated Sludge Process ◽  
Cycle Times ◽  
Waste Sludge ◽  
Volatile Solids ◽  
In Series ◽  
Flow Through ◽  
Theoretical Simulations

The laboratory scale experimental investigation comprised a 6 day sludge age activated sludge process, the waste sludge of which was fed to a number of digesters operated as follows: single reactor flow through digesters at 4 or 6 days sludge age, under aerobic and anoxic-aerobic conditions (with 1,5 and 4 h cycle times) and 3-in-series flow through aerobic digesters each at 4 days sludge age; all digesters were fed draw-and-fill wise once per day. The general kinetic model for the aerobic activated sludge process set out by Dold et al., (1980) and extended to the anoxic-aerobic process by van Haandel et al., (1981) simulated accurately all the experimental data (Figs 1 to 4) without the need for adjusting the kinetic constants. Both theoretical simulations and experimental data indicate that (i) the rate of volatile solids destruction is not affected by the incorporation of anoxic cycles and (ii) the specific denitrification rate is independent of sludge age and is K4T = 0,046(l,029)(T-20) mgNO3-N/(mg active VSS. d) i.e. about 2/3 of that in the secondary anoxic of the single sludge activated sludge stystem. An important consequence of (i) and (ii) above is that denitrification can be integrated easily in the steady state digester model of Marais and Ekama (1976) and used for design (Warner et al., 1983).

Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

2004 ◽  
Vol 82 (8) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vanessa Renée Little ◽  
Keith Vaughan
Keyword(s):  
Free Energy ◽  
Chemical Shifts ◽  
Linear Free Energy Relationship ◽  
Piperazine Ring ◽  
Linear Free Energy ◽  
In Series ◽  
Methylene Groups ◽  
Diazonium Coupling ◽  
The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

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