Journal articles: 'Glass transition temperature'

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CONIGLIO, ANTONIO. "FRACTALS IN THE GLASS TRANSITION." Fractals 04, no. 03 (September 1996): 349–54. http://dx.doi.org/10.1142/s0218348x96000467.

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The static and fractal properties of the frustrated percolation model are investigated. This model, which contains frustration as an essential ingredient, displays glassy behavior at high density or low temperature and exhibits two transitions: a percolation transition at a temperature Tp with critical exponents of the ferromagnetic s=1/2 state Potts model, and a second transition at a lower temperature Tg in the same universality class of the Ising spin glass model.

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Ouyang, L. F., J. Shen, Y. Huang, Y. H. Sun, H. Y. Bai, and W. H. Wang. "Strong-to-fragile transition in a metallic-glass forming supercooled liquid associated with a liquid–liquid transition." Journal of Applied Physics 133, no. 8 (February 28, 2023): 085105. http://dx.doi.org/10.1063/5.0137847.

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Liquid–liquid transitions are present in a variety of substances. However, investigating the liquid–liquid transitions occurring in a supercooled liquid is difficult because of the interference from rapid crystallization. Here, we report a strong-to-fragile transition in a Pd32Ni52P16 metallic glass-forming supercooled liquid associated with a liquid–liquid transition. Since the liquid–liquid transition takes place at temperatures smaller than the crystallization temperature, the liquid viscosity can be acquired by creep experiments conducted at temperatures close to the glass transition temperature without interference from crystallization. The strong-to-fragile transition results in a 37% increase of the fragility index and a 56% elongation after thermal-plastic processing. An investigation on the loss-modulus peaks by a dynamic mechanical analyzer implies that the enhanced thermal plasticity is contributed by both glass transition and strong-to-fragile transition. This work highlights how liquid–liquid transition affects liquid fragility and how it may aid the thermal-plastic processing of metallic glass.

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Reis, Ana Karoline dos, Francisco Maciel Monticelli, Roberta Motta Neves, Luis Felipe de Paula Santos, Edson Cocchieri Botelho, and Heitor Luiz Ornaghi Jr. "Creep behavior of polyetherimide semipreg and epoxy prepreg composites: Structure vs. property relationship." Journal of Composite Materials 54, no. 27 (May 22, 2020): 4121–31. http://dx.doi.org/10.1177/0021998320927774.

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In the present study, the creep behavior of polyetherimide semipreg and epoxy prepreg composites was studied using dynamic mechanical analyzer and focused on structure vs. property relationships in glassy, glass transition, and elastomeric regions. The main contribution to the field is to study pre-impregnated materials concerning creep behavior, mainly based on different analytical models, and microstructure. Two different reinforcements were used (carbon fiber and glass fiber) for each matrix. Findley, Burger, and Weibull analytical models were applied with an excellent fit for the most of them. The impregnation quality, verified by C-scan and the void content by acid digestion, shows different impregnation behaviors, mainly for epoxy/CF, which also influenced molecular motion behavior. The creep behavior was mainly influenced by matrix type than reinforcement architecture and void content. In addition, the creep was higher for epoxy in the glassy region; however, in the glass transition region, higher deformation was found for polyetherimide composites. Previous behavior is mainly attributed to higher energy storage in the glassy region which plays a significant role in the dissipation (glass transition energy), resulting in the energy loss or the drop of storage modulus in a narrow temperature range – more abrupt. This behavior was corroborated by time-temperature superposition curves in which the low deformation obtained for polyetherimide composites at low temperatures is maintained only until the glass transition temperature. Epoxy composites showed a higher initial creep deformation, but the values were almost constant with temperature, even when the temperature passes by the glass transition temperature.

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Heireche, M. M., L. Heireche, and M. Belhadji. "Thermal stability and glass transition kinetics in GeTeSb glasses by using non-isothermal measurement." Chalcogenide Letters 19, no. 10 (November 3, 2022): 735–41. http://dx.doi.org/10.15251/cl.2022.1910.735.

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In this paper we have analysed the thermal properties of three different compositions of chalcogenide glasses Ge15Te85-xSbx (x=0.5, 1, 1.5). The samples have been prepared using the melt quenching technique and the characterisation is done using X-ray diffraction. The compositional dependence on properties were studied using Differential Scanning Calorimetry (DSC) analysis using non-isothermal measurement. The glassy sample crystallized by two transition temperatures Tg1 and Tg2.The dependence of glass transition temperature on heating rate has been studied by Lasocka empirical relation and the Kissinger equation. As a result, the apparent activation energy for glass transition has been determined. Thermal stability has also been determined from the temperature difference between the onset crystallization and glass transition temperature.

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ZHOU, BO, YAN-JU LIU, XIN LAN, JIN-SONG LENG, and SUNG-HO YOON. "A GLASS TRANSITION MODEL FOR SHAPE MEMORY POLYMER AND ITS COMPOSITE." International Journal of Modern Physics B 23, no. 06n07 (March 20, 2009): 1248–53. http://dx.doi.org/10.1142/s0217979209060762.

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As novel smart materials, shape memory polymer (SMP) and its composite (SMPC) have the ability to regain its original shape after undergoing significant deformation upon heating or other external stimuli such as light, chemic condition and so on. Their special behaviors much depends on the glass transitions due to the increasing of material temperature. Dynamic Mechanical Analysis (DMA) tests are performed on the styrene-based SMP and its carbon fiber fabric reinforced SMPC to investigate their glass transition behaviors. Three glass transition critical temperatures of SMP or SMPC are defined and a method to determine their values from DMA tests is supposed. A glass transition model is developed to describe the glass transition behaviors of SMP or SMPC based on the results of DMA tests. Numerical calculations illustrate the method determining the glass transition critical temperature is reasonable and the model can well predict the glass transition behaviors of SMP or SMPC.

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Su, Ming Horng, and Hung Chang Chen. "A Molecular Dynamics Investigation into the Cooling Characteristics of Ni and Cu Alloys at High Pressure." Materials Science Forum 505-507 (January 2006): 1093–98. http://dx.doi.org/10.4028/www.scientific.net/msf.505-507.1093.

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This paper studies the phase transitions of Cu and Ni alloys as they cool from melting temperature to room temperature under high-pressure conditions. The interatomic forces acting between the atoms are modeled by the tight-binding potential. Control over the environmental pressure and the cooling temperature is maintained by a canonical ensemble (N, P, T) system. The numerical results confirm that the metal phase transition is influenced significantly by the pressure conditions, even in the case of pure Cu and Ni metals. Three specific transition pathways are identified for the Cu and Ni alloys as they cool from melting temperature to room temperature, namely a transition at the melting temperature to a crystalline structure, a transition at the glass transition temperature to a glass (amorphous) structure, and finally solidification at the melting temperature followed by a subsequent transition at the glass transition temperature. The results reveal that glass transition generally occurs at lower pressures in alloys with higher Cu compositions, while glass transition following prior solidification tends to takes place at higher pressures in alloys with higher Ni compositions.

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Jin, H. J., and K. Lu. "An indirect approach to measure glass transition temperature in metallic glasses." International Journal of Materials Research 97, no. 4 (April 1, 2006): 388–94. http://dx.doi.org/10.1515/ijmr-2006-0065.

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Abstract Glass transition behavior of metallic glasses under some extraordinary conditions (such as under high pressures) remains unexplored. Conventional measurements of glass transition temperature, T g, are very difficult to perform under these extraordinary circumstances. In the present paper, we introduce an indirect approach to characterize glass transition, using enthalpy recovery experiments. With annealing deeply relaxed glassy samples and subsequent DSC measurements, a variation of enthalpy change upon heating with annealing temperature can be obtained. The variation of enthalpy change, a signature of glass transition, was found to correlate well with the directly measured DSC curves for the glass transition. This unique method was successfully applied in determining T g of several metallic glasses under hydrostatic high pressures and compression stresses.

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Verma, Arvind Kumar, Anchal Srivastava, R. K. Shukla, and K. C. Dubey. "Thermal Behavior of Chalcogenide glasses Te90Se10 and Se90Te10." SAMRIDDHI : A Journal of Physical Sciences, Engineering and Technology 7, no. 02 (December 25, 2015): 113–18. http://dx.doi.org/10.18090/samriddhi.v7i2.8636.

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In the present research work melt quenching method has been adopted to prepare the glassy Te-rich (Te90Se10) and Se-rich (Se90Te10 ) Chalcogenide at a pressure of 10-2 Torr with constant Temperature at 1000°C for 8 hours. Devitrification characteristics of the pure glassy Chalcogenide Te90Se10 and Se90Te90 were investigated by using Differential scanning Calorimetry (DSC) 4000 Perkin Elmer. All the measurements carried out at fixed heating rate 10 0C/min under non-isothermal conditions. The Glass transition temperature (Tg) and other thermal properties were examined by temperature modulated differential scanning Calorimetry at 40 oC to 445 oC. Glass transition temperature (Tg) represents the strength or rigidity of the glass structure. Tg affords valuable information on the thermal stability of the glassy state but Tg alone does not give any information on the glass forming tendency. The difference of the Peak crystallization temperature (Tp) and Glass transition temperature (Tg) is a strong indication of the thermal stability. The higher the value of Tc and Tg the greater is the thermal stability. Glass transition temperature (Tg=2160C) of Tellurium rich (Te90Se10) is more than Glass transition temperature (Tg=730C) of Selenium rich (Se90Te90) due to semi metallic nature of Tellurium. The difference of (Tp-Tg) is a strong indicator of both the thermal stability and Glass forming ability (GFA). Higher the value of (Tp-Tg), higher is the thermal stability and GFA because higher values of this difference indicate more kinetic resistance to the crystallization. Glass forming ability (GFA) and thermal stability of Te90Se10 is greater than Se90Te90. For memory and switching materials, glass thermal stability and GFA parameters are very important. Intensity of Se-rich (Se90Te10) is more than Te-rich (Te90Se10) and both samples are polycrystalline in nature.

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Luque, Patricia, and Antonio Heredia. "Glassy State in Plant Cuticles during Growth." Zeitschrift für Naturforschung C 49, no. 3-4 (April 1, 1994): 273–75. http://dx.doi.org/10.1515/znc-1994-3-419.

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The existence of a glassy state in isolated tomato fruit cuticles was investigated using differential scanning calorimetry. Tomato fruit cuticular membranes showed a glass transition temperature at -30 °C and an additional second order transition temperature near 30 °C. Changes in these temperatures during fruit growth were also studied

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KRASNOV, K. V., N. M. CHALAYA, and V. S. OSIPCHIK. "Research of technological properties of mixed compositions based on polyolefin thermoplastic elastomers." Plasticheskie massy 1, no. 1-2 (March 30, 2022): 14–15. http://dx.doi.org/10.35164/0554-2901-2022-1-2-14-15.

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Technological properties – phase transitions of mixed compositions based on polyolefin thermoplastic elastomers have been studied. The melting point and glass transition temperature of compositions were determined by DSC and DMA methods. The influence of the type of elastomer on the melting and glass transition temperatures of a mixed composite material is revealed.

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Сандитов, Д. С., В. В. Мантатов, and С. Ш. Сангадиев. "Oбобщенный кинетический критерий перехода жидкость--стекло." Физика твердого тела 62, no. 10 (2020): 1706. http://dx.doi.org/10.21883/ftt.2020.10.49925.082.

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Using the model of delocalized atoms, a substantiation and generalization of the Schmelzer glass transition criterion is proposed. In contrast to the Bartenev and Volkenstein - Ptitsyn approaches, in the generalized kinetic glass transition criterion, along with the relaxation time and the cooling rate of the melt, the glass transition temperature and an almost universal dimensionless constant appear, which is determined by the fraction of the fluctuation volume frozen at the glass transition temperature. The idea is developed that the liquid goes into a glassy state when its cooling rate q reaches a certain fraction of C_g of the characteristic cooling rate q_g=(T_g/taug), which is closely related to the relaxation time of the structure tau_g at the glass transition temperature T_g.

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12

Bartenev, G. M., and A. G. Barteneva. "Relaxation Transitions in Elastomers at Temperatures above the Glass Transition Temperature." International Polymer Science and Technology 33, no. 2 (February 2006): 9–14. http://dx.doi.org/10.1177/0307174x0603300203.

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13

Liang, Taining, Yong Yang, Dawei Guo, and Xiaozhen Yang. "Conformational transition behavior around glass transition temperature." Journal of Chemical Physics 112, no. 4 (January 22, 2000): 2016–20. http://dx.doi.org/10.1063/1.480761.

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14

Wei, Wen-Hou. "Effects of chemical composition and mean coordination number on glass transitions in Ge–Sb–Se glasses." Modern Physics Letters B 31, no. 36 (December 13, 2017): 1750342. http://dx.doi.org/10.1142/s0217984917503420.

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Glass transitions in the Ge–Sb–Se glasses were investigated by means of differential scanning calorimetry (DSC) under non-isothermal conditions. The glass transition temperature [Formula: see text], activation energy of glass transition [Formula: see text], and fragility index as functions of the mean coordination number (MCN) and atomic percent of Ge were examined. The maximum value of [Formula: see text] in each group of the glasses occurred at the chemically stoichiometric composition, suggesting a glass transition threshold. The [Formula: see text] and fragility index were calculated from the heating rate dependence of [Formula: see text]. Both [Formula: see text] and fragility index show the minima at MCN = 2.4 which can be attributed to the structural phase transition of a covalently glassy network at MCN = 2.4. The analysis of the experimental results suggests that both the chemical composition and MCN have significant effects on the glass transitions in Ge–Sb–Se glasses.

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Hanhi, K., and B. Stenberg. "Friction and the Dynamic Mechanical and Thermal Properties of Polyurethane Elastomers. 1. Solid Polyurethanes." Cellular Polymers 12, no. 6 (November 1993): 461–93. http://dx.doi.org/10.1177/026248939301200604.

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The results reported indicate that the properties of polyurethanes elastomers can be tailored to serve a wide variety of applications, for low temperature uses as well. The glass transition temperatures of the soft segments (Tgs) which control the low temperature properties of polyurethane elastomers, ranged from -79°C to -27°C (DSC onset values). The transitions observed in the range 75 to 125°C were attributed to hard segment glass transitions. The transitions at temperatures from 140 to 170°C, which were identified especially in the samples of over stoichiometric diisocyanate concentration, evidently arose from the dissociation of allophanate crosslinks and successive ordering processes. The low temperature β” and γ transitions were observed at temperatures from -70°C to -125°C. In addition to the obvious Schatzki crankshaft mechanism, allophanate crosslinking may influence these transitions. Samples that were annealed over the crystal melting temperature and subsequently quenched exhibited higher glass transition temperatures than the samples kept for a long time at room temperature. These results can be explained in terms of better phase separation in annealing and formation of small soft segment crystallites in quenching, in contrast to the formation of large crystalline and amorphous phases in the RT samples.

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Sheveleva, M. G., L. V. Taranova, and S. G. Agaev. "A dielectric investigation of structural-phase transitions in oils." Oil and Gas Studies, no. 6 (January 11, 2023): 110–25. http://dx.doi.org/10.31660/0445-0108-2022-6-110-125.

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The article deals with issues related to the mechanism of solidification of oils. The authors present the results of a dielectric investigation of structural-phase transitions in oils from the fields of Tyumen region in the temperature range -110 ÷ +20 °С. The dielectric relaxation of oils has been established, the values of the activation energy and dielectric relaxation time have been calculated. The phase transition determined by dielectric relaxation is interpreted as a transition from the glassy state to the associated state. The glass transition of oils, accompanied by the cessation of internal rotation in hydrocarbon molecules, is a sign of their true (or viscous) solidification. The glass transition temperature and the temperature region of the structural solidification of oils were determined. The glass transition temperature is considered to be the true pour point. The relationships between the physicochemical characteristics of oils and the parameters characterizing their dielectric properties were established, which were studied by the methods of correlation and regression analysis. The obtained regression equations can be used to predict the physico-chemical characteristics of oils in the technological processes of their extraction, field preparation and transportation.

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Forrest, J. A., and K. Dalnoki-Veress. "When Does a Glass Transition Temperature Not Signify a Glass Transition?" ACS Macro Letters 3, no. 4 (March 17, 2014): 310–14. http://dx.doi.org/10.1021/mz4006217.

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Wang, Wei Hua, Ping Wen, D. Q. Zhao, M. X. Pan, and Ru Ju Wang. "Relationship between glass transition temperature and Debye temperature in bulk metallic glasses." Journal of Materials Research 18, no. 12 (December 2003): 2747–51. http://dx.doi.org/10.1557/jmr.2003.0382.

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The Debye temperature and glass transition temperature of a variety of bulk metallic glasses (BMGs) were determined by acoustic measurement and differential scanning calorimetry, respectively. The relationship between the Debye temperature and glass transition temperature of these BMGs was analyzed, and their observed correlation was interpreted in terms of the characteristics of the glass transition in BMGs.

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CHAUDHARY, S., V. MODGIL, and V. S. RANGRA. "EFFECT OF COMPOSITIONAL VARIATION ON PHYSICAL PARAMETERS OF QUATERNARY CHALCOGENIDE GLASSES Se69Sn10Ge21-xSbx (6≤x≤14)." Journal of Ovonic Research 16, no. 1 (January 2020): 41–52. http://dx.doi.org/10.15251/jor.2020.161.41.

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The glassy alloysSe69Sn10Ge21-xSbx (where x= 6, 8, 10, 12, 14) are prepared by melt quench technique. The physical parameters have been studied such as average coordination number, number of constraints, floppy mode, Lone pair electron, mean bond energy and glass transition temperature etc.The chemical bond approach has been used to calculate cohesive energy of the samples. The mean bond energy and glass transition temperature has been calculated using Tichy-Ticha Approach. It has been observed from the study that with addition of Sb, the parameters such as average coordination number, mean bond energy and glass transition temperature decreases.

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Kajňaková, Marcela, Alexander Feher, Elena Fertman, Vladimir Desnenko, Anatoly Beznosov, and Sergiy Dolya. "Nanophase Separation and Magnetic Spin Glass in Nd_2/3Ca_1/3MnO₃." Solid State Phenomena 190 (June 2012): 675–78. http://dx.doi.org/10.4028/www.scientific.net/ssp.190.675.

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A study of the low temperature magnetic state of polycrystalline colossal magnetoresistance perovskite Nd2/3Ca1/3MnO3 has been carried out. The data obtained, such as strongly divergent ZFC and FC static magnetizations and frequency dependent ac susceptibility, are evident of the glassy magnetic state of the system. Well defined maxima Tmax in the in-phase linear ac susceptibility χ curves were observed, indicating a spin-glass transition. Clear frequency dependence of the cusp temperature Tmax was found. The frequency dependence of Tmax was successfully analyzed by the dynamical scaling theory of a three-dimensional spin glass. Slow relaxation process and variety of relaxation times found imply a cluster glass magnetic state of the compound at low temperatures rather than a canonical spin glass state. The cluster glass state, accompanied by the multiple magnetic transitions of Nd2/3Ca1/3MnO3, might exist due to the competing interaction between the FM clusters and the AFM matrix induced by the complex nanophase segregated state of the compound.

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Stunda, Agnese, Nina Mironova-Ulmane, Natalija Borodajenko, and Liga Berzina-Cimdina. "Phase Transition in Niobophosphate Glass-Ceramic." Advanced Materials Research 222 (April 2011): 259–62. http://dx.doi.org/10.4028/www.scientific.net/amr.222.259.

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Phase transition during crystallization of glass to glass-ceramic in system P2O5-CaO-Nb2O5-Na2O was studied. Several heating rates were compared – 1, 2, 5, 11 and 20°Cmin-1. DTA, XRD, FTIR and Raman analyses were performed. Niobophosphate glass-ceramic is found to form utterly different crystalline phases depending on maximal heating temperature, heating rate and time of maximal temperature maintenance. Crystallization temperatures of the same phases are strongly dependent on heating rate, while crystallinity of obtained phases is not. At lower temperatures poorly crystalline phosphates (Ca3(PO4)2, Ca10Na(PO4)7, Ca2P2O7) and niobates (NaNbO3 and Nb2O5) are identified. At higher temperatures a large amount of well crystalline niobophosphate (Na4(Nb8P4O32) and Ca2P2O7 forms. With increasing amount of Na4(Nb8P4O32), amount of NaNbO3 and Nb2O5 decreases.

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Elwardany, Michael D., Jean-Pascal Planche, and Jeramie J. Adams. "Determination of Binder Glass Transition and Crossover Temperatures using 4-mm Plates on a Dynamic Shear Rheometer." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 10 (May 16, 2019): 247–60. http://dx.doi.org/10.1177/0361198119849571.

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The accurate rheological characterization of asphalt binder properties, as a function of pavement service life, is crucial to improving asphalt binder specifications, modifications, and formulation methods. Bitumen streams from refineries have experienced significant changes since the development of SHRP Superpave specifications as a result of economic, technical, and environmental reasons. Binder rheological behavior is divided into three regions: near glassy region, terminal region, and an intermediate “transition” region between them. At a reference frequency, these regions are separated by two characteristic temperatures: (1) the glass transition temperature (Tg), which is the temperature between the near glassy region and the intermediate region, and (2) the crossover temperature (TG’=G”), which is the temperature between the intermediate region and the terminal region. In this study, Tg and TG’=G” of 50 binders were obtained from a dynamic shear rheometer (DSR) using 4-mm parallel plates. Glass transition temperatures from DSR were compared with those obtained from modulated differential scanning calorimetry (DSC). Tg and TG’=G” were also compared with continuous low-PG temperatures and ΔTc parameter. Results indicate that critical temperatures based on the creep stiffness and the relaxation rate can be determined from Tg and TG’=G”, respectively. Furthermore, ΔTc parameter correlates well with the intermediate region temperature range (TIR).

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Fairhurst, C. W., D. T. Hashinger, and S. W. Twiggs. "The Effect of Thermal History on Porcelain Expansion Behavior." Journal of Dental Research 68, no. 9 (September 1989): 1313–15. http://dx.doi.org/10.1177/00220345890680090401.

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Porcelain-fused-to-metal restorations are fired several hundred degrees above the glass-transition temperature and cooled rapidly through the glass-transition temperature range. Thermal expansion data from room temperature to above the glass-transition temperature range are important for the thermal expansion of the porcelain to be matched to the alloy. The effect of heating rate during measurement of thermal expansion was determined for NBS SRM 710 glass and four commercial opaque and body porcelain products. Thermal expansion data were obtained at heating rates of from 3 to 30°C/min after the porcelain was cooled at the same rate. By use of the Moynihan equation (where Tg systematically increases in temperature with an increase in cooling/heating rate), the glass-transition temperatures (Tg) derived from these data were shown to be related to the heating rate.

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Zamani, Nurhidayah R., Aidah Jumahat, and Rosnadiah Bahsan. "Dynamic Mechanical Analysis of Nanosilica Filled Epoxy Nanocomposites." Applied Mechanics and Materials 699 (November 2014): 239–44. http://dx.doi.org/10.4028/www.scientific.net/amm.699.239.

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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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da Silva, Antônio Carlos, S. C. Santos, and Sonia Regina Homem de Mello-Castanho. "Transition Metals in Glass Formation." Materials Science Forum 727-728 (August 2012): 1496–501. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.1496.

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The structure of silicate glasses gets its charge stability through SiO2, R2O3, R2+and R+groups arrangement. In these glassy structures, transition metals are usually used as dopants in small amounts. However, in soda-lime glass systems, transition metals can take part in the glassy network in larger quantities as secundary former or modifier, insted R2+groups, if the charge balance conditions are made favorable by R2O3groups additions. This paper studies transition metals (Cr, Ni, Fe, Cu, Zn, Pb, Ru) soda-lime-borosilicate glass network incorporation. This process was applied for many kinds of toxic metals containing vitrification waste. The glasses were obtaind by melt at temperature of 1300°C, and characterized by FT-IR and XRD techinics. The chemical stability was evaluated by hydrolytic attack test. The glasses showed a high chemistry and environmental stability like the soda-lime glass.Keywords: glass structure, electroplating waste, e-waste, nanowaste.

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Araki, W., T. Adachi, M. Gamou, and A. Yamaji. "Time-temperature dependence of fracture toughness for bisphenol a epoxy resin." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 216, no. 2 (April 1, 2002): 79–84. http://dx.doi.org/10.1177/146442070221600203.

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The relationship between the curing conditions and the time-temperature dependence of fracture toughness was investigated for bisphenol A epoxy resin. The glass transition temperature and Angell's fragility parameter, which are obtained from thermoviscoelasticity measurements, were used to characterize epoxy resins cured under various conditions. Examination of the fracture toughness at various temperatures and displacement rates showed that it depends on both temperature and time, and that it follows the time-temperature equivalence principle. The time-temperature dependence of the fracture toughness was greatly affected by the fragility parameter. The fracture toughness of the resin with a smaller fragility parameter increased from lower temperatures to the brittle-ductile transition temperature than that of the resin with a larger fragility parameter when their glass transition temperatures were approximately 400 K. It was also found that the brittle-ductile transition temperature did not depend on the fragility parameter. This means that epoxy resin with a smaller fragility parameter has better fracture characteristics than epoxy resin with a larger fragility parameter if their glass transition temperatures are approximately 400 K.

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Zhang, Yue, Shachi Katira, Andrew Lee, Andrew T. Lambe, Timothy B. Onasch, Wen Xu, William A. Brooks, et al. "Kinetically controlled glass transition measurement of organic aerosol thin films using broadband dielectric spectroscopy." Atmospheric Measurement Techniques 11, no. 6 (June 19, 2018): 3479–90. http://dx.doi.org/10.5194/amt-11-3479-2018.

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Abstract. Glass transitions from liquid to semi-solid and solid phase states have important implications for reactivity, growth, and cloud-forming (cloud condensation nuclei and ice nucleation) capabilities of secondary organic aerosols (SOAs). The small size and relatively low mass concentration of SOAs in the atmosphere make it difficult to measure atmospheric SOA glass transitions using conventional methods. To circumvent these difficulties, we have adapted a new technique for measuring glass-forming properties of atmospherically relevant organic aerosols. Aerosol particles to be studied are deposited in the form of a thin film onto an interdigitated electrode (IDE) using electrostatic precipitation. Dielectric spectroscopy provides dipole relaxation rates for organic aerosols as a function of temperature (373 to 233 K) that are used to calculate the glass transition temperatures for several cooling or heating rates. IDE-enabled broadband dielectric spectroscopy (BDS) was successfully used to measure the kinetically controlled glass transition temperatures of aerosols consisting of glycerol and four other compounds with selected cooling and heating rates. The glass transition results agree well with available literature data for these five compounds. The results indicate that the IDE-BDS method can provide accurate glass transition data for organic aerosols under atmospheric conditions. The BDS data obtained with the IDE-BDS technique can be used to characterize glass transitions for both simulated and ambient organic aerosols and to model their climate effects.

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Atayeva, S. U., A. I. Isayev, S. I. Mekhtiyeva, S. N. Garibova, R. I. Alekberov, and F. N. Mammadov. "Glass transition and crystallization of Se95Te5 chalcogenide glassy semiconductor." Chalcogenide Letters 21, no. 4 (May 13, 2024): 355–63. http://dx.doi.org/10.15251/cl.2024.214.355.

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The study is dedicated to the investigation of thermo-physical characteristics of Se95Te5 chalcogenide glassy semiconductor during its glass formation and crystallization processes, employing various scanning rates of 5, 10, 15 and 20 K/min in non-isothermal modes through DSC measurement. Analysis of the structural relaxation kinetics involves the Kissinger’s, Augis and Bennett's, as well as Matusita’s approaches. Experimental data yield contains the determination of crucial parameters such as glass transition (𝑇𝑇𝑔𝑔), crystallization(𝑇𝑇𝑐𝑐), and melting temperatures alongside factors like reduced temperature of glass transition (𝑇𝑇𝑟𝑟𝑟𝑟), Hruby’s parameter (𝐾𝐾𝑔𝑔𝑔𝑔), fragility index (𝐹𝐹𝑖𝑖), Avrami exponents (n, m), glass transition (140.24 kJ/mol) and crystallization (Ec = 95.11 kJ/mol) energies, respectively. The results confirm that Se95Te5 chalcogenide system as an efficient glass former. Matusita’s method reveals that the crystallization mechanism (n = 2.51, m = 1.9) corresponds to volumetric nucleation with two-dimensional growth.

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Wang, Ben, Bowen Yang, Minghai Wang, Yaohui Zheng, Xianjun Hong, and Fan Zhang. "Effect of Cutting Temperature on Bending Properties of Carbon Fibre Reinforced Plastics." Science and Engineering of Composite Materials 26, no. 1 (January 28, 2019): 394–401. http://dx.doi.org/10.1515/secm-2019-0019.

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AbstractHigh cutting temperatures are easily generated during the machining of carbon fibre reinforced plastics (CFRP) and can induce serious damage during machining such as delamination. The purpose of this paper is to study the influence of cutting temperature on the performance of CFRP after machining. CFRP specimens were heated to temperatures within the vicinity of cutting temperatures generated during machining, then air-cooled and their bending properties investigated. The results showed that temperature had significant influence on the bending stress of CFRP. With increasing temperature, bending stress decreased and was lowest when the temperature was close to the glass-transition temperature. It was concluded that the bending properties of CFRP could be seriously affected if the material temperature was close to the glass-transition temperature and maintained for a period. As a result, cutting temperature should be kept lower than the glass transition temperature during machining.

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Mishra, Surabhi, Priyanka Jaiswal, Pooja Lohia, and D. K. Dwivedi. "Annealing Effect on the Optical Properties of Multi Walled Carbon Nano Tube Doped Cu5Se75Ge10In10 Thin Films Prepared by Thermal Evaporation Method." Advanced Science, Engineering and Medicine 12, no. 1 (January 1, 2020): 78–82. http://dx.doi.org/10.1166/asem.2020.2527.

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The optical properties of as prepared and annealed [(Cu5Se75Ge10In10)99 (CNT)1] thin films deposited with thermal evaporation technique has been discussed as a function of photon energy in wavelength range 300–900 nm in present paper. The bulk sample of as prepared glassy alloys were developed using the melt quench technique. Thin films of prepared glassy alloys were deposited on a glass substrate with thermal evaporation unit at room temperature at base pressure of ∼10–5 Pa. The films were annealed at two different temperatures between glass transition temperature and crystallization temperatures. Analysis of the optical data shows that optical bandgap decreases with increasing annealing temperature while extinction coefficient, absorption coefficient and transmission shows increasing behaviour with increase in annealing temperature.

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Iwagaki, Sakiko, Hiroki Kakuta, Yasuhisa Yamamura, Hideki Saitoh, Mafumi Hishida, Kazuhiro Fukada, and Kazuya Saito. "Ordering Phase Transition with Symmetry-Breaking from Disorder over Non-Equivalent Sites: Calorimetric and Crystallographic Study of Crystalline d-Sorbose." Crystals 10, no. 5 (May 1, 2020): 361. http://dx.doi.org/10.3390/cryst10050361.

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Phase transitions in the crystalline state of chiral sorbose were examined using precise heat capacity calorimetry and X-ray crystallography. The calorimetry established heat capacity below room temperature. Besides the known transition (main transition) at 199.5 K, the calorimetry detected plural thermal anomalies assignable to new phase transitions (around 210 K) and a glass transition (at ca. 120 K). The X-ray diffraction at low temperatures established the crystal structure of the lowest temperature phase. The identification of the broken symmetry upon the main transition solves an apparent contradiction that the structural disorder reported previously does not contribute seemingly to the symmetrization.

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Yoon, Heedong, and Gregory B. McKenna. "Testing the paradigm of an ideal glass transition: Dynamics of an ultrastable polymeric glass." Science Advances 4, no. 12 (December 2018): eaau5423. http://dx.doi.org/10.1126/sciadv.aau5423.

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A major challenge to understanding glass-forming materials is obtaining equilibrium data far below the laboratory glass transition temperatureTg. The challenge arises because it takes geologic aging times to achieve the equilibrium glassy state when temperatures are well belowTg. Here, we finesse this problem through measurements on an ultrastable amorphous Teflon with fictive temperatureTfnear to its Kauzmann temperatureTK. In the window betweenTfandTg, the material has a lower molecular mobility than the equilibrium state because of its low specific volume and enthalpy. Our measurements show that the determined scaled relaxation times deviate strongly from the classical expectation of divergence of time scales at a finite temperature. The results challenge the view of an ideal glass transition at or near toTK.

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Stoev, Krassimir, and Kenji Sakurai. "X-ray reflectivity study of the glass transition temperature of thin films." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C885. http://dx.doi.org/10.1107/s2053273314091141.

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The glass transition takes place in amorphous materials (like polymers) during heating or cooling, and can be described as reversible transition from a hard and brittle state into a rubber-like state. Although physical properties of the material change significantly during the glass transition, this is not a phase transition of the material. The temperature at which the transition between the glassy and rubbery state occurs is called the glass transition temperature, and this temperature is always lower than the melting temperature. Thermodynamically, the glass transition is associated with transfer of heat between the system and its surrounding and with an abrupt volume change. Previously it was shown that the glass transition temperature of nano-films is different from that of bulk materials [1], which signifies the importance of determining this parameter for such systems. In the current work, we use quick X-ray reflectivity (qXRR) measurements to determine the glass transition temperature of polyvinyl acetate (PVAc). PVAc is rubbery synthetic polymer with the formula (C4H6O2), a density of 1.18 g/cm3, and a glass transition temperature for bulk material of 30oC [2]. Regular X-ray reflectivity measurements are based on θ/2θ scans at grazing incidence and typically require 0.5-1.5 h for a single scan. The qXRR technique is based on simultaneous measurement of the whole angular x-ray reflectivity profile and is suitable for in-situ measurement without moving the sample and/or the x-ray optics. Thus, the qXRR technique allows for very fast measurement of the x-ray reflectivity curves (duration of each scan is typically 0.1–20 sec [3]), which permits studying the time evolution of chemical, thermal, and mechanical changes at the surface and interface of different materials. X-ray reflectivity measurements give information about both density and thickness of thin films, and are suitable for studying glass transition phenomena. Nano-thickness PVAc layers on a Si substrate were examined with the qXRR technique, with x-ray reflectivity scans (each 10-seconds in duration) being recorded while temperature was changed from 20 to 50oC (total of 331 scans over 7 hours and 46 minutes). In the current paper, the experimental setup, the data-processing, and the analysis of the results from the qXRR measurements will be presented.

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Badrinarayanan, Prashanth, Wei Zheng, Qingxiu Li, and Sindee L. Simon. "The glass transition temperature versus the fictive temperature." Journal of Non-Crystalline Solids 353, no. 26 (August 2007): 2603–12. http://dx.doi.org/10.1016/j.jnoncrysol.2007.04.025.

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35

Sharifi, Soheil. "Temperature Dependence of the Activation Volume of Secondary Relaxation in Glass Formers." ISRN Materials Science 2011 (July 25, 2011): 1–5. http://dx.doi.org/10.5402/2011/460751.

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We study a nonmonotonic behavior with temperature of the activation volume ΔVβ of secondary relaxation in PPGE [Poly[(phenyl glycidyl ether)-co-formaldehyde]] and PVAc [Poly(vinyl acetate)] glass formers. Our results show that the non-monotonic behaviour of secondary relaxation does not depend on the type of the secondary relaxation. Moreover, the study of secondary relaxation under pressure at isothermal paths shows two different behaviours of ΔVβ in the glassy state (which describe two different types of glasses); for temperatures higher than the glass transition temperature (Tg), ΔVβ increases with a decrease of the temperature while at temperatures lower than Tg, ΔVβ decreases with a decrease of the temperature.

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36

Monkos, Karol. "The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin." Current Topics in Biophysics 39, no. 1 (December 1, 2016): 13–25. http://dx.doi.org/10.1515/ctb-2016-0005.

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Abstract The paper presents the results of viscosity determinations on aqueous solutions of ovalbumin at a wide range of concentrations and at temperatures ranging from 5°C to 55°C. On the basis of these measurements and three models of viscosity for glass-forming liquids: Avramov’s model, free-volume model and power-law model, the activation energy of viscous flow for solutions and ovalbumin molecules, at different temperatures, was calculated. The obtained results show that activation energy monotonically decreases with increasing temperature both for solutions and ovalbumin molecules. The influence of the energy of translational heat motion, protein-protein and protein-solvent interactions, flexibility and hydrodynamic radius of ovalbumin on the rate of decrease in activation energy with temperature has been discussed. One of the parameters in the Avramov’s equation is the glass transition temperature Tg. It turns out that the Tg of ovalbumin solutions increases with increasing concentration. To obtain the glass transition temperature of the dry ovalbumin, a modified Gordon-Taylor equation is used. Thus determined the glass transition temperature for dry ovalbumin is equal to (231.8 ± 6.1) K.

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Nabiałek, M. "Reduced Glass-Transition Temperature versus Glass-Forming Ability in FeCoB-Based Amorphous Alloys." Archives of Metallurgy and Materials 61, no. 4 (December 1, 2016): 1957–62. http://dx.doi.org/10.1515/amm-2016-0315.

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AbstractThis work presents studies concerning the relationship between reduction of glass transition temperatureTrgand the glass-forming ability of FeCoB-based alloys. On the basis of theoretical considerations, Turnbull [1] determined the reduced glass transition temperature (Tg/Tl) as being 2/3 of the Vogel–Fulcher–Tammann (VFT) temperature; since then, continuous research has been carried out, aiming to calculate the Trg parameter and describe its relationship with glass-forming ability. In the majority of research papers, the reduced glass transition temperature is calculated from the relationshipTg/Tm, proposed by Uhlmann and Davies [2, 3]. On the basis of differential scanning calorimetry (DSC) studies, undertaken in this current work, the values of the following temperatures have been found:Tg,Tx, Tmand Tl, in addition to the temperature ranges:ΔTx,ΔTmandΔTl. The correlation between:Tg/Tm,Tg/Tland the glass-forming ability also has been discussed. Finally, for the investigated alloys, it has been found that the relationship proposed by Turnbull is reliable over a wide range ofΔTm.

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Peng, Shirley, and Jude O. Iroh. "Dependence of the Dynamic Mechanical Properties and Structure of Polyurethane-Clay Nanocomposites on the Weight Fraction of Clay." Journal of Composites Science 6, no. 6 (June 14, 2022): 173. http://dx.doi.org/10.3390/jcs6060173.

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The effect of clay and chemical cross-linking on the dynamic mechanical properties of polyurethane reinforced with different concentrations of organically modified montmorillonite clay is investigated in this study. The polyurethane matrix is constituted of polytetrahydrofuran soft segment and 4,4′-methylenebis(phenyl isocyanate) hard segment. Glycerin was used as the chemical crosslinking agent, while Cloisite 30B clay was the reinforcing filler. The nanocomposites containing up to 1 wt.% clay showed a uniform dispersion of clay; however, the nanocomposites containing higher concentrations of clay showed the presence of heterogeneities. Dynamic mechanical spectroscopy, DMS revealed that the nanocomposites containing between 2 and 10 wt.% clay had two glass transition temperatures, Tg,1 and Tg,2. The higher-temperature glass transition temperature, Tg,2 increased with increasing clay concentration, while the low-temperature glass transition temperature, Tg,1 decreased with increasing clay concentration. The nanocomposites containing low clay concentrations up to 1 wt.% showed only one glass transition temperature with a narrow glass transition region. The crosslink density for the nanocomposites increased with increasing wt.% clay.

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39

El-Eskandarany, M. Sherif, Wei Zhang, and A. Inoue. "Mechanically induced solid-state reaction for synthesizing glassy Co75Ti25 soft magnet alloy powders with a wide supercooled liquid region." Journal of Materials Research 17, no. 9 (September 2002): 2447–56. http://dx.doi.org/10.1557/jmr.2002.0357.

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A single phase of glassy Co75Ti25 alloy powders was synthesized by high-energy ball milling the elemental powders at room temperature, using the mechanical alloying method. The final product of the glassy alloy, which is obtained after ball milling for 86 ks, exhibits soft magnetic properties with polarization and coercivity values of 0.67 T and 2.98 kA/m, respectively. This binary glassy alloy, in which its glass transition temperature (Tg) lies at a rather high temperature (833 K), transforms into face-centered-cubic Co3Ti (ordered phase) at 889 K through a single sharp exothermic reaction with an enthalpy change of crystallization (ΔHx) of −2.35 kJ/mol. The supercooled liquid region before crystallization ΔTx of the synthesized glassy powders shows an extraordinary high value (56 K) for a metallic binary system. The reduced glass transition temperature [ratio between Tg and liquidus temperatures, Tl (Tg/Tl)] was 0.56. We also demonstrated postannealing experiments of the mechanically deformed Co/Ti multilayered composite powders. The results show that annealing of the powders at 710 K leads to the formation of a glassy phase (thermally enhanced glass formation reaction). Its heat formation was measured directly and found to be −0.56 kJ/mol. The similarity in the crystallization and magnetization behaviors between the two classes of as-annealed and as-mechanically alloyed glassy powders implies the formation of the same glassy phase.

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Kim, Jong Sun, Kyung Hwan Yoon, and Julia A. Kornfield. "Measurement of Stress-Optical Coefficients of COC’s with Different Composition." Key Engineering Materials 326-328 (December 2006): 183–86. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.183.

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Rheo-optical and mechanical properties of Cyclic Olefin Copolymers(COC’s) with different composition have been investigated across the glass transition temperature. Accurate measurement of stress or strain-optical coefficients and elastic modulus data across the glass transition are essential for predicting optical anisotropy in many optical products like pickup lenses and waveguides in LCD backlight unit since the material of these products have both flow and thermal history from the melt to glass. To obtain stress-optic behavior in the wide frequency region including rubbery, glassy and glass transition regime, extensional bar-type device was used. A shear-sandwich tool was used in the melt region. Master curves for modulus, stress-optical and strain-optical coefficients have been obtained in wide frequency region. The stress-optical coefficients of COC’s with mol fraction of norbornene, 60 ~ 70%, showed almost constant between -8 and -9 Br at glassy region and between +920 and +1,160 Br in the melt region. Even though the glass transition temperature showed the difference of 35, the stress-optical coefficients of COC’s with different composition showed almost same extreme values

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Anantrao, JoshiHrushikesh, JangmeChandraprabhu Motichand, and BhasmeSamrudhi Narhari. "A REVIEW ON: GLASS TRANSITION TEMPERATURE." International Journal of Advanced Research 5, no. 8 (August 31, 2017): 671–81. http://dx.doi.org/10.21474/ijar01/5105.

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42

Rieger, J. "The glass transition temperature of polystyrene." Journal of Thermal Analysis 46, no. 3-4 (March 1996): 965–72. http://dx.doi.org/10.1007/bf01983614.

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43

Ding, Jianfu, Gi Xue, Qingping Dai, and Rongshi Cheng. "Glass transition temperature of polystyrene microparticles." Polymer 34, no. 15 (January 1993): 3325–27. http://dx.doi.org/10.1016/0032-3861(93)90412-4.

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Hossain, Md D., Derong Lu, Zhongfan Jia, and Michael J. Monteiro. "Glass Transition Temperature of Cyclic Stars." ACS Macro Letters 3, no. 12 (November 24, 2014): 1254–57. http://dx.doi.org/10.1021/mz500684v.

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Hutchinson, John M. "Determination of the glass transition temperature." Journal of Thermal Analysis and Calorimetry 98, no. 3 (August 28, 2009): 579–89. http://dx.doi.org/10.1007/s10973-009-0268-0.

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46

Heuer, Andreas, and Hans W. Spiess. "Universality of the glass transition temperature." Journal of Non-Crystalline Solids 176, no. 2-3 (November 1994): 294–98. http://dx.doi.org/10.1016/0022-3093(94)90090-6.

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47

Utracki, L. A. "Glass transition temperature in polymer blends." Advances in Polymer Technology 5, no. 1 (1985): 33–39. http://dx.doi.org/10.1002/adv.1985.060050105.

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Morozov, V. N., and S. G. Gevorkian. "Low-temperature glass transition in proteins." Biopolymers 24, no. 9 (September 1985): 1785–99. http://dx.doi.org/10.1002/bip.360240909.

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Avramov, I., and I. Gutzow. "Heating rate and glass transition temperature." Journal of Non-Crystalline Solids 104, no. 1 (August 1988): 148–50. http://dx.doi.org/10.1016/0022-3093(88)90194-9.

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50

Рыжов, В. А. "Универсальные особенности проявления взаимосвязи локальной и сегментальной динамики в стеклообразных полимерах на терагерцовых частотах в инфракрасных спектрах." Оптика и спектроскопия 131, no. 1 (2023): 30. http://dx.doi.org/10.21883/os.2023.01.54534.4323-22.

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Low-frequency IR- spectra of glassy polymers were obtained and analyzed at temperatures from 90 to 400K. Temperature changes in the IR- spectra in the range from 10 to 140 cm-1 show three universal features: low-temperature, corresponding to the torsional-vibrational motion of monomer units, high-temperature, due to the influence of primary relaxation (glass transition) and intermediate, caused by the activation of conformational mobility in chains at a temperature of β - transition. This versatility extends both to polymers with universal chain-to-chain interactions and to those with hydrogen bonds.

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Journal articles on the topic 'Glass transition temperature'

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