Comparison of Magnetostrictive Performance Loss of Particulate Tb0.3 Dy0.7 Fe2 Epoxy Composites Prepared with Different Matrix Polymers M. Shanmugham et al.: Comparison of Magnetostrictive Performance Loss of Particulate Tb0.3 Dy0.7 Fe2 Epoxy Composites

2004 ◽  
Vol 19 (3) ◽  
pp. 795-805 ◽  
Author(s):  
Manikantan Shanmugham ◽  
Harold Bailey ◽  
William D. Armstrong
Keyword(s):  
Magnetic Field ◽  
Glass Transition ◽  
Matrix Material ◽  
Epoxy Composites ◽  
Particulate Composites ◽  
Specimen Preparation ◽  
Performance Loss ◽  
Magnetostrictive Strain ◽  
Relative Damage ◽  
Low Modulus

Particulate composites of magnetostrictive Terfenol-D were prepared with polyamine and anhydride cured epoxy polymer matrices with the presence or the absence of a strong magnetic field. These composites were studied to investigate (i) the influence of magnetic field that is applied during specimen preparation in strain output levels, (ii) performance loss at high temperatures, and (iii) the influence of matrix material in magnetostrictive strain performance. A six-way comparison is made of materials processed under magnetic field with materials processed under no magnetic field, and magnetostrictive strain performance at glass transition finish temperature with magnetostrictive strain performance at glass transition start temperature, and magnetostrictive strain performance in low modulus matrix systems with magnetostrictive strain performance in high modulus matrix systems. A four-way comparison is also made between the micrographs for strain-cycled and non-strain-cycled samples and relative damage incurred by samples prepared using high and low modulus matrix systems.

Influence of humidity on the dielectric behaviour of BaTiO3–epoxy composites

2019 ◽  
Vol 54 (13) ◽  
pp. 1639-1646 ◽  
Author(s):  
C Gonzalez Aguilar ◽  
M Reboredo ◽  
M Castro
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Water Absorption ◽  
Room Temperature ◽  
Dielectric Behavior ◽  
Epoxy Composites ◽  
Particulate Composites ◽  
Second Phase ◽  
Absorption Process ◽  
Pure Resin

Epoxy resin and their particulate composites are widely used in different industries, as aeronautical, automotive, microelectronics and coatings. The water absorption can deteriorate the properties on these materials when they are used in service. Many factors influence in water absorption process, as the quantity of hydroxyls groups, the glass transition temperature of the resin or the presence of a dispersed second phase. Thus, the objective of this work is to determine the dielectric behavior of BaTiO3–epoxy composites in different humid environments (controlled moisture of 80, 50 and 30%) and at room temperature. Results of pure resin samples show that dielectric permittivity increases with the percentage of absorbed water and that this increase is greater for the samples exposed to more humid environments. Interestingly, the addition of ceramic particles not only increases the composite dielectric properties but also reduces the water absorption in all the cases.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

Enhanced dielectric response under applied magnetic field in 0–3 particulate composites of (1−x)PbZr0.95Ti0.05O3-(x)Ni0.7Zn0.3Fe2O4

2021 ◽  
Vol 127 (8) ◽  
Author(s):  
Rahul Goel ◽  
Manoj Kumar ◽  
Shobhna Dhiman ◽  
Arun Kumar Singh ◽  
Sanjeev Kumar
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Dielectric Response ◽  
Particulate Composites

MAGNETIC RESISTIVITY IN Bi2Sr2Ca(Cu1-xCox)2Od EPITAXIAL THIN FILMS

2007 ◽  
Vol 21 (01) ◽  
pp. 127-132
Author(s):  
T. R. YANG ◽  
G. ILONCA ◽  
V. TOMA ◽  
P. BALINT ◽  
M. BODEA
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Activation Energy ◽  
Glass Transition ◽  
Effective Activation Energy ◽  
Epitaxial Thin Films ◽  
Effective Activation ◽  
High Quality ◽  
Plastic Deformations ◽  
Magnetic Resistivity

The scaling behavior of the effective activation energy of high-quality epitaxial c-oriented Bi 2 Sr 2 Ca ( Cu 1-x Co x)2 O d thin films with 0≤x ≤0.025 has been studied as a function of temperature and magnetic field. For all samples, the effective activation energy scales as U(T, μoH)=Uo(1-T/T c )mHn with exponent m=1.25±0.03, n=-1/2 and the field scaling 1/μoH and -UμoH for thick films and ultra thin films, respectively. The results are discussed taking into account of the influence of the Co substitution with a model in which U(T, H) arises from plastic deformations of the viscous flux liquid above the vortex-glass transition temperature.

Spin-glass transition in a magnetic field

1985 ◽  
Vol 51 (5) ◽  
pp. 543-556 ◽  
Author(s):  
H. Sompolinsky
Keyword(s):  
Magnetic Field ◽  
Glass Transition ◽  
Spin Glass ◽  
Spin Glass Transition

scholarly journals Epoxy Resin Composite Bilayers with Triple-Shape Memory Effect

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xixi Li ◽  
Yaofeng Zhu ◽  
Yubing Dong ◽  
Meng Liu ◽  
Qingqing Ni ◽  
...  
Keyword(s):  
Glass Transition ◽  
Electron Microscope ◽  
Shape Memory ◽  
Memory Effects ◽  
Epoxy Composites ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Shape Memory Effects ◽  
Triple Shape Memory ◽  
Nanosilica Particles

Triple-shape memory epoxy composites with bilayer structures of well-separated glass transition temperatures have been successfully prepared. The different glass transition temperatures of the epoxy composites were obtained by physically incorporating various amounts of nanosilica particles, which were introduced into the epoxy by utilizing polyethylene glycol. A scanning electron microscope and a transmission electron microscope were used to analyze the dispersibility of the nanosilica particles. The effects of nanosilica particles on the mechanical properties as well as on the dual-shape memory effects (DSME) and triple-shape memory effects (TSME) of the nanocomposites were studied. The nanosilica particles were homogenously dispersed in the matrix and well incorporated into the epoxy matrix. The resulting nanocomposites exhibited excellent TSME, and their shape fixity properties were significantly improved by nanosilica particles.

Dynamic Mechanical Analysis of Nanosilica Filled Epoxy Nanocomposites

2014 ◽  
Vol 699 ◽  
pp. 239-244 ◽  
Author(s):  
Nurhidayah R. Zamani ◽  
Aidah Jumahat ◽  
Rosnadiah Bahsan
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Polymer ◽  
Loss Modulus ◽  
Matrix Material ◽  
Mechanical Analysis ◽  
Dynamic Mechanical ◽  
Mechanical Stirring ◽  
Tan Δ

In this study, Dynamic Mechanical Analyzer (DMA) was used to study the effect of nanoparticles, which is nanosilica, on glass transition temperature (Tg) of epoxy polymer. A series of epoxy based nanosilica composite with 5-25 wt% nanosilica content was prepared using mechanical stirring method. The weight fractions of nanosilica in epoxy were 5 wt%, 13 wt% and 25 wt%. 30mm x 10mm x 3mm size specimens were tested using DMA machine from room temperature up to 180oC at 2°C/min heating rate. From the analysis of the results, dynamic modulus and glass transition temperature of pure polymer and nanosilica filled polymer were obtained. The glass transition of a polymer composite is a temperature-induced change in the matrix material from the glassy to the rubbery state during heating or cooling. Glass transition temperature Tg was determined using several method: storage modulus onset, loss modulus peak, and tan δ peak. The results showed that the presence of nanosilica reduced Tg of epoxy polymer.

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