Porosity and the Effect of Structural Changes on the Mechanical Glass Transition Temperature

2007 ◽  
Vol 55 (6) ◽  
pp. 2459-2466 ◽  
Author(s):  
Stefan Kasapis ◽  
Shyam S. Sablani ◽  
M. Shafiur Rahman ◽  
Insaf M. Al-Marhoobi ◽  
Issa S. Al-Amri
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Changes

Thermo-mechanical properties and thermal conductivity of CdS-trans-polyisoprene, polymer nanocomposite

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Mahesh Baboo ◽  
Manasvi Dixit ◽  
Dinesh Patidar ◽  
Kananbala Sharma ◽  
Narendra Sahai Saxena
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Modulus ◽  
Structural Changes ◽  
Polymer Nanocomposite ◽  
Cds Nanoparticles ◽  
Chemical Route

Abstract This paper focuses on the comparative evaluation of the glass transition temperature (Tg), storage modulus and thermal conductivity of trans-polyisoprene (TPI) and CdS-TPI nanocomposite. The CdS nanoparticles synthesized by chemical route are dispersed into TPI using ultrasonic vibrations. Particle size of nanocrystals is obtained from X-ray diffraction and found to be 1.84 nm. Thermo-mechanical properties (Tg and storage modulus) are measured by dynamic mechanical analyzer (DMA), while thermal conductivity is a measured using the transient plane source (TPS) technique. It is observed that glass transition temperature and thermal conductivity are higher while storage modulus and mechanical properties are lower for CdS-TPI nanocomposites than for pure TPI. This has been explained on the basis of structural changes occurring due to introduction of CdS as filler into the TPI.

Ultrasonic Properties of a Ti47.4Zr5.3Ni5.3Cu42 Glassy Alloy during Progressive Devitrification

2007 ◽  
Vol 561-565 ◽  
pp. 1371-1374 ◽  
Author(s):  
Ichiro Seki ◽  
Mikio Fukuhara ◽  
Akihisa Inoue
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Relaxation ◽  
Structural Changes ◽  
Poisson Ratio ◽  
Glassy Alloy ◽  
Acoustic Characteristics ◽  
Ultrasonic Properties ◽  
Devitrification Process

Although a Ti47.4Zr5.3Ni5.3Cu42 glassy alloy does not occur precipitation of crystalline in annealing of prolonged time below glass transition temperature, it shows slightly embrittlement during passing through devitrification process. The embrittlment behavior may be connected to structural relaxation. Using ultrasonic, in this study, acoustic characteristics of the glassy alloy during progressive devitrification were examined in terms of structural relaxation. The structural changes are characterized by decreases in specific volume, bulk modulus, Lamè parameter and Poisson ratio, accompanied by structural relaxation.

Structural changes in amorphous arsenic triselenide below the glass-transition temperature

1993 ◽  
Vol 164-166 ◽  
pp. 1239-1242 ◽  
Author(s):  
Hiroyoshi Naito ◽  
Hitoshi Amii ◽  
Masahiro Okuda ◽  
Tatsuhiko Matsushita
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Changes ◽  
Arsenic Triselenide

Effects of Polar Solvent on the Structure and Properties of M-Aramid Fibers

2012 ◽  
Vol 441 ◽  
pp. 169-173 ◽  
Author(s):  
Hua Peng Zhang ◽  
Xin Xing Feng ◽  
Hai Lin Zhu ◽  
Jian Yong Chen
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Changes ◽  
Polar Solvent ◽  
Fiber Structure ◽  
Aramid Fibers ◽  
Solvent Treatment ◽  
Dimensional Changes ◽  
Dyeing Process

The effects of polar solvent on the surface morphology, glass transition temperature, crystalline structure, dimensional changes and dye uptakes of m-aramid fibers were characterized by SEM, DSC, XRD, FTIR and dyeing process after dimethyl sulfoxide (DMSO) solvent treatment under different conditions. After DMSO solvent treatment, the surface of the fiber is roughened, the diameter of the fiber increases, and the specific surface area is increased. The crystallite size shows a little increase, but the glass transition temperature of the fiber drops sharply. Electron diffraction shows that effects of DMSO on the fiber structure is non-uniform, and the obvious structural changes lie on the outer surface of the fiber. Dye uptake increase has been achieved through the DMSO induced structural changes. The results have been used to improve the dyeability of meta-aramid fiber.

Thermal Relaxations of Polymers Revealed by Reversing and Non-Reversing Coefficient of Thermal Expansion

2010 ◽  
Vol 123-125 ◽  
pp. 451-454
Author(s):  
Robert A. Shanks
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Expansion Coefficient ◽  
Structural Changes ◽  
Coefficient Of Thermal Expansion ◽  
Modulated Temperature ◽  
Heating And Cooling ◽  
Modulated Temperature Dsc

Reversible and irreversible events can be resolved) using modulated temperature DSC and TMA. Each technique has advantages, those for TMA include longer times and slower scan rates that allow greater approach to material equilibrium. The thermal expansion coefficient and glass transition temperature can be isolated from relaxations and structural changes. Modulated temperature thermomechanometry (mT-TM) is used to characterize amorphous thermoplastics including PS, PMMA, PC and PPO, and the results including annealing, heating and cooling.

A Possible Mechanism For Atomic Transport in Amorphous Metals

1997 ◽  
Vol 481 ◽  
Author(s):  
Leon D. Van Ee ◽  
Barend J. Tthijsse ◽  
Jilt Sietsma
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Diffusion Process ◽  
Structural Changes ◽  
Low Frequency ◽  
Vibrational Modes ◽  
Atomic Transport ◽  
Localized Vibrational Modes ◽  
Irreversible Nature

ABSTRACTThe diffusion process at a temperature just below the glass-transition temperature is studied in a computer model of amorphous Ni81B19. The observed diffusion events cause structural changes that are highly localized and are correlated with low-frequency localized vibrational modes. The excitation of such a mode can result in a “jump”, which is identical to the diffusion event. The jump has a cooperative character involving some tens of atoms and can be of a reversible or of an irreversible nature.

Structural and Optical Properties of Li2O–NaF–ZnO–P2O5:(CdO + S) Glass System

2017 ◽  
Vol 6 (1) ◽  
pp. 108-115 ◽  
Author(s):  
Mohammed A. Algradee ◽  
A. A. Higazy ◽  
S. Wageh
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Molar Volume ◽  
Absorption Spectra ◽  
Spectral Range ◽  
Glass Matrix ◽  
Structural Changes ◽  
Quenching Method ◽  
The Fourier Transform

Glasses having composition 5Li2O-33NaF-7ZnO-55P2O5: x wt% (CdO + S) where x = 0.0, 1.0, 2.0, 3.0 and 4.0 wt%, were prepared by the melt quenching method and their amorphous nature was confirmed by X-ray diffraction technique. Variations in density (ρ), molar volume (Vm) and glass transition temperature (Tg) have been correlated with structural changes in the glass matrix. The optical absorption spectra of the polished samples were recorded in spectral range from 200 to 1000 nm at room temperature. The optical band gap (Eopt.) and Urbach energy (ΔE) were determined from the absorption spectra. These parameters (Eopt., ΔE) were found to vary depending on the composition of the glasses. The Fourier-transform Infrared (FTIR) spectra have been recorded in the spectral range from 400 to 4000 cm–1. The FTIR reveals that the addition of Cd2+ ions provide ionic cross-linking between the non-bridging oxygen of different chains and increasing the bond strength of this ionic cross-link which confirmed by decrease in the molar volume and increase in the glass transition temperature when (CdO + S) content is increased. The compositional dependences of the above properties are discussed and correlated with the structural changes in glass matrix.

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