Bridging and caging in mixed suspensions of microsphere and adsorptive microgel

Soft Matter ◽  
2014 ◽  
Vol 10 (44) ◽  
pp. 8905-8912 ◽  
Author(s):  
Chuanzhuang Zhao ◽  
Guangcui Yuan ◽  
Charles C. Han
Keyword(s):  
Glass Transition ◽  
Volume Fraction ◽  
Mixing Ratio ◽  
Mixed Suspension

Gelation and glass transition in a mixed suspension of polystyrene (PS) microsphere and poly(N-isopropylacrylamide) (PNIPAM) microgel were studied as a function of the total colloid volume fraction and mixing ratio of these two components.

scholarly journals The effective complex permittivity stability in filled polymer nanocomposites studied above the glass transition temperature

2018 ◽  
Vol 149 ◽  
pp. 01080 ◽  
Author(s):  
F. Elhaouzi ◽  
A. Mdarhri ◽  
M. Zaghrioui ◽  
C. Honstettre ◽  
I. El Aboudi ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Complex Permittivity ◽  
Dielectric Response ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Low Frequencies ◽  
Neat Polymer

The temperature effecton the dielectric response of nanocomposite at low frequencies range is reported. The investigated samples are formed by a semi-crystalline ethylene-co-butyl acrylate (EBA) polymer filled with three concentrations of the dispersed conducting carbon black (CB) nanoparticles. The temperature dependence of the complex permittivity has been analyzedabove the glass transition temperature of the neat polymer matrix Tg=-75°C. For all CB concentrations, the dielectric spectra follow a same trend in frequency range 100-106Hz. More interestingly, the stability of the effective complex permittivity ɛ=ɛ' -iɛ'' with the temperature range of 10-70°C is explored. While the imaginary part of the complex permittivity ɛ'' exhibits a slight decreasewith temperature, the real part ɛ' shows a significant reduction especially for high loading samples. The observed dielectric response may be related to the breakup of the three-dimensional structurenetwork formed by the aggregation of CB particles causing change at the interfaceEBA-CB.This interface is estimated bythe volume fraction of constrained polymer chain according to loss tangent data of dynamic mechanical analysis.

APPLICATION OF REED-VIBRATION MECHANICAL SPECTROSCOPY FOR LIQUIDS IN STUDYING LIQUID CRYSTALLIZATION

2013 ◽  
Vol 27 (21) ◽  
pp. 1350080 ◽  
Author(s):  
HENG-WEI ZHOU ◽  
LI-NA WANG ◽  
LI-LI ZHANG ◽  
YI-NENG HUANG
Keyword(s):  
Glass Transition ◽  
Room Temperature ◽  
Crystallization Process ◽  
Volume Fraction ◽  
Supercooled Liquid ◽  
Avrami Exponent ◽  
Dimethyl Phthalate ◽  
Mechanical Spectroscopy ◽  
Crystal Volume ◽  
Complex Young’S Modulus

By using the reed-vibration mechanical spectroscopy for liquids (RMS-L), we measured the complex Young's modulus of dimethyl phthalate (DP) during a cooling and heating circulation starting from room temperature at about 2 KHz. The results show that there is no crystallization in the cooling supercooled liquid (CSL) of DP, but a crystallization process in the heating supercooled liquid (HSL) after the reverse glass transition. Based on the measured modulus, crystal volume fraction (v) during the HSL crystallization was calculated. Moreover, the Avrami exponent (n) was obtained according to the JJMA equation and v data. In view of n versus temperature and v, the nucleation dynamics was analyzed, and especially, there has already existed saturate nuclei in DP HSL before the crystallization. Furthermore, the authors inferred that the nuclei are induced by the random frozen stress in the glass, but there is no nucleus in CSL. The above results indicated that RMS-L might provide a new way to measure and analyze the crystallization of liquids.

Homogeneous flow of bulk metallic glass composites with a high volume fraction of reinforcement

2007 ◽  
Vol 22 (6) ◽  
pp. 1564-1573 ◽  
Author(s):  
X.L. Fu ◽  
Y. Li ◽  
C.A. Schuh
Keyword(s):  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Volume Fraction ◽  
High Volume ◽  
Strain Rate Range ◽  
Homogeneous Deformation ◽  
Deformation Analysis ◽  
Glass Composites ◽  
Glass Matrix Composites

We present a systematic study of homogeneous deformation in a La-based bulk metallic glass and two in situ composites based on the same glass. In contrast to prior investigations, which focused on relatively dilute composites, in this work the reinforcement volume percentages were more concentrated at 37% and 52%—near or above the percolation threshold (35–40%). Hot uniaxial compressive testing was conducted over a wide strain rate range from 10−2to 10−5s−1at a temperature near the glass transition. For such concentrated composites, the homogeneous deformation behavior appeared to be dominated by the properties of the reinforcement phase; in the present case the La reinforcements deformed by glide-controlled creep. Post-deformation analysis suggested that bulk metallic glass matrix composites were susceptible to microstructural evolution, which appeared to be enhanced by deformation, in contrast with a stress-free anneal. Consequently, unreinforced bulk metallic glass appeared to be more structurally stable than its composites during deformation near the glass transition.

Dynamic Mechanical Analysis of Fly Ash Filled Polyurea Elastomer

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Jing Qiao ◽  
Alireza V. Amirkhizi ◽  
Kristin Schaaf ◽  
Sia Nemat-Nasser
Keyword(s):  
Glass Transition ◽  
Fly Ash ◽  
Dynamic Mechanical Analysis ◽  
Volume Fraction ◽  
Loss Modulus ◽  
Mechanical Analysis ◽  
Temperature Dependent ◽  
Dynamic Mechanical ◽  
Storage And Loss Moduli ◽  
Temperature Superposition

In this work, the material properties of a series of fly ash/polyurea composites were studied. Dynamic mechanical analysis was conducted to study the effect of the fly ash volume fraction on the composite’s mechanical properties, i.e., on the material’s frequency- and temperature-dependent storage and loss moduli. It was found that the storage and loss moduli of the composite both increase as the fly ash volume fraction is increased. The storage and loss moduli of the composites relative to those of pure polyurea initially increase significantly with temperature and then slightly decrease or stay flat, attaining peak values around the glass transition region. The glass transition temperature (measured as the temperature at the maximum value of the loss modulus) shifted toward higher temperatures as the fly ash volume fraction increased. Additionally, we present the storage and loss moduli master curves for these materials obtained through application of the time-temperature superposition on measurements taken at a series of temperatures.

A Model for Irradiation-Induced Amorphization

1997 ◽  
Vol 504 ◽  
Author(s):  
S. X. Wang ◽  
L. M. Wang ◽  
R. C. Ewing
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Dependence ◽  
Dose Rate ◽  
Volume Fraction ◽  
Ion Irradiation ◽  
Crystallization Rate ◽  
Single Equation ◽  
Sigmoidal Functions

ABSTRACTA model based on cascade melting and recrystallization is derived to describe ion irradiation-induced amorphization. The accumulation of amorphous volume fraction during irradiation is represented in a single equation. Depending on the extent of recrystallization of a subcascade, the amorphous volume accumulation can be described by a set of curves that change from exponential to sigmoidal functions. The parameters (including temperature, cascade size, crystallization rate, glass transition temperature, dose rate) that affect the extent of recrystallization are included in the model. The model also describes the temperature dependence of critical dose for amorphization.

Effect of layering pattern and fiber hybridization on viscoelastic properties of PALF/COIR hybrid epoxy composites

2021 ◽  
Vol 15 (1) ◽  
pp. 7894-7906
Author(s):  
Mohit Mittal ◽  
Rajiv Chaudhary
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Properties ◽  
Volume Fraction ◽  
Interfacial Region ◽  
Damping Factor ◽  
Structural Applications ◽  
Fiber Matrix ◽  
Hybrid Biocomposite

To design and develop a hybrid biocomposite material for structural applications, it becomes necessary to determine the optimum fibers layering pattern. Therefore, in this research work, the different layered hybrid biocomposite boards i.e. bilayer pineapple/coir (P/C), trilayer (PCP, CPC), and intimately mixed (IM) were developed and characterized for viscoelastic properties. The composites were made by hand lay-up method, keeping the volume ratio of PALF and COIR 1:1 and the total fiber volume fraction is 0.40 volume of composite. Dynamic mechanical thermal analysis test was employed to characterize the viscoelastic behavior in terms of storage modulus, loss modulus, loss damping factor, and the glass transition temperature. Amongst all the different layered hybrid composites, the trilayer CPC has lowest value (0.635) of effectiveness coefficient with highest stiffness and activation energy (40.54 kJ/mole). It confirms the better fiber-matrix interaction at the interfacial region. The glass transition temperature of CF-EP and PF-EP was increased by 8.74% and 13.15% respectively by the synergistic hybridization of cellulosic fibers. The PCP layered composite possesses lowest value of phase transition energy (9.17 kJ/mole) and this was because of the poor fiber-matrix interfacial adhesion.

Synthesis and Properties of Bulk Amorphous/Nanocrystalline Aluminum Alloy Composites

2006 ◽  
Vol 510-511 ◽  
pp. 830-833 ◽  
Author(s):  
Si Joon Noh ◽  
Taek Kyun Jung ◽  
Dong Suk Lee ◽  
Mok Soon Kim ◽  
Sung Yi
Keyword(s):  
Volume Fraction ◽  
Grain Structure ◽  
Full Density ◽  
Mixing Ratio ◽  
Forging Process ◽  
High Maximum ◽  
Nanocrystalline Aluminum ◽  
Maximum Compressive Strength ◽  
Rapidly Solidified ◽  
Equiaxed Grain

The rod-shaped bulk composites consisting of Al-10Ni-6Ce and Al-4Fe-0.6Mo-1.1V- 0.3Zr alloy (mixing ratio; 0.7:0.3, 0.5:0.5 and 0.3:0.7) and corresponding monolithic alloys were produced to a full density via powder forging process. The process involved pre-compaction of rapidly solidified alloy powders and subsequent isothermal forging at 673K. The forged Al-10Ni- 6Ce alloy exhibited nano-scaled crystalline particles, such as fcc-Al, Al3Ni, Al4Ce and Al11Ce3 phase, coexisting with an amorphous phase. In the case of the forged Al-4Fe-0.6Mo-1.1V-0.3Zr alloy, an equiaxed grain structure was observed to exist with uniformly distributed nano-scaled Al- Fe based intermetallics. The monolithic Al-10Ni-6Ce alloy had a considerably high maximum compressive strength (MCS) of 1.35 GPa without showing any compressive plastic strain (CPS). In contrast, the monolithic Al-4Fe-0.6Mo-1.1V-0.3Zr alloy possessed noticeably high CPS of 25% with the MCS of 0.71GPa. The composites acquired the CPS varying from 1 to 5.8 % and the MCS from 1.26 to 0.74 GPa, with increment of the volume fraction of Al-4Fe-0.6Mo-1.1V-0.3Zr alloy from 0.3 to 0.7.

Characterizing and Modeling the Free Recovery and Constrained Recovery Behavior of a Polyurethane Shape Memory Polymer

2010 ◽  
Author(s):  
Brent L. Volk ◽  
Dimitris C. Lagoudas ◽  
Duncan J. Maitland
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Tensile Tests ◽  
Stress Recovery ◽  
Shear Moduli ◽  
Recovery Experiment

In this work, tensile tests are performed on a polyurethane shape memory polymer for both free recovery (extension recovery at zero load) and constrained recovery (stress recovery at constant extension) conditions. The experimental characterization is conducted on an electromechanical screw driven test frame, and a laser extensometer is used in conjunction with the electromechanical frame to provide a non-contact technique for measuring the deformation of the material. The specimens are deformed, above the glass transition temperature, to 10% extension. The SMP is then cooled, at a constant value of extension, to below the glass transition temperature to ‘lock’ the temporary shape. The extension recovery at zero load as well as the stress recovery at a constant value of extension is measured during the first shape memory cycle as the SMP is heated to above its glass transition temperature. The material is observed to recover 93% of the applied deformation when heated at zero load. In addition, a stress recovery of 1.5 MPa is observed when heated while holding a constant value of deformation (10% extension). After performing the experiments, the Chen and Lagoudas model, implemented in 1-D by Volk, et al., is used to simulate and predict the experimental results. The material properties used in the model — namely the coefficients of thermal expansion, shear moduli, and frozen volume fraction — are calibrated from a single free recovery experiment. The calibrated model is then used to simulate the material response for the free recovery tests as well as predict the response for the constrained recovery condition. The model simulations agree well with the free recovery experimental data but predict a larger compressive stress than what is observed during the constrained recovery experiment.

Viscosities of Oxynitride Glass and the Effects on High Temperature Behaviour of Silicon Nitride-Based Ceramics

2005 ◽  
Vol 287 ◽  
pp. 259-264 ◽  
Author(s):  
Stuart Hampshire ◽  
Michael J. Pomeroy
Keyword(s):  
Glass Transition ◽  
Rare Earth ◽  
High Temperature ◽  
Silicon Nitride ◽  
Volume Fraction ◽  
Temperature Behaviour ◽  
Rare Earth Cation ◽  
Intergranular Films ◽  
Oxynitride Glass ◽  
Earth Cation

M-Si-Al-O-N glasses (where M = Y or rare earth cation) are intergranular phases in silicon nitride based ceramics in which the composition and volume fraction of these oxynitride glass phases determine the properties of the material, in particular, high temperature mechanical behaviour. Investigations on oxynitride glass formation and properties have shown that nitrogen increases the glass transition and softening temperatures, viscosity, elastic modulus and hardness. By changing the cation ratios or the type of rare earth cation incorporated, properties such as viscosity can be increased further. This paper provides an overview of oxynitride glasses and outlines the effect of composition on properties such as glass transition temperature and viscosity. These effects have important implications for silicon nitride based ceramics where amorphous intergranular films control high temperature properties such as creep resistance.

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