Structural effects on glass stability and crystallization

CrystEngComm ◽  
2018 ◽  
Vol 20 (16) ◽  
pp. 2278-2283 ◽  
Author(s):  
A. M. Rodrigues ◽  
L. D. Silva ◽  
R. Zhang ◽  
V. O. Soares
Keyword(s):  
Activation Energy ◽  
Glass Structure ◽  
Structural Effects ◽  
Crystallization Activation Energy ◽  
Glass Stability

We report the correlation between glass stability, crystallization activation energy and the glass structure to one pure devitrite glass (Na2Ca3Si6O16), and two other glasses in which 4 mol% and 8 mol% of devitrite glass were replaced with TiO2 (Dev, 4Ti and 8Ti, respectively).

Structure, Glass Stability and Crystallization Activation Energy of SrO-CaO-B2O3-SiO2 glasses doped with TiO2

2021 ◽  
Vol 554 ◽  
pp. 120605
Author(s):  
Maria V.S. Alencar ◽  
Glauco V.P. Bezerra ◽  
Laís D. Silva ◽  
José F. Schneider ◽  
M. Jesus Pascual ◽  
...  
Keyword(s):  
Activation Energy ◽  
Crystallization Activation Energy ◽  
Glass Stability

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

Freestanding FeCrAl-Y2O3 Amorphous/Crystalline Composite Coating Fabricated by Electron-Beam Physical Vapor Deposition

2014 ◽  
Vol 788 ◽  
pp. 652-656
Author(s):  
Xiu Lin ◽  
Guang Ping Song ◽  
Hua Song Gou ◽  
Yi Jie Zhao ◽  
Yang Chen ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electron Beam ◽  
Substrate Temperature ◽  
Composite Coating ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Room Temperature ◽  
Crystallization Activation Energy ◽  
Substrate Side ◽  
Columnar Grains

Freestanding FeCrAl-Y2O3 amorphous/crystalline composite coating with a thickness of about 200μm has been produced from electron-beam physical vapor deposition of FeCrAl and yttria materials with a substrate temperature of 500 oC around. The microstructure was composed of columnar grains near the substrate side and an amorphous top layer. Local crystallization occurred during room temperature preservation. It is inferred that the crystallization activation energy of the material is very low.

Crystallization Behavior and Microstructure of B2O3-Al2O3-SiO2 Glass-Ceramics

2008 ◽  
Vol 51 ◽  
pp. 149-154
Author(s):  
Han Ning Xiao ◽  
Tao Sun ◽  
Hua Bin Liu ◽  
Yin Cheng
Keyword(s):  
Activation Energy ◽  
Metal Oxides ◽  
Crystalline Phase ◽  
Crystallization Behavior ◽  
Glass Ceramics ◽  
Earth Metal ◽  
Crystallization Activation Energy ◽  
Alkali Earth Metal ◽  
Alkali Earth ◽  
Bulk Crystallization

The influences of B2O3/SiO2 ratio and different alkali earth metal oxides MO (M= Ba, Mg, Ca) on the crystallization behavior of B2O3-Al2O3-SiO2 (BAS) glass were investigated by means of DSC, XRD and SEM. With the reduction of B2O3/SiO2 ratio, the crystallization activation energy increases at first and then decreases, reaching the minimum value of 375.4 kJ·mol-1 when the B2O3/SiO2 ratio is 2.2. The crystalline indices (n) are all more than 4, which indicates that the glass is in bulk crystallization. When the glass was heated to 800°C, the primary precipitated crystalline phase was Al4B2O9. With the increase of temperature up to 1100°C, Al18B4O33 and Al5BO9 appeared and became the major crystalline phases in BAS glass-ceramics.

scholarly journals Isothermal and Non-Isothermal Crystallization Kinetics of PVDF and PVDF/PMMA Blends

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Jianbin SONG ◽  
Yuan CAI ◽  
Bin ZHANG ◽  
Lixin TANG ◽  
Rongrong SHI ◽  
...  
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Crystallization Rate ◽  
Crystallization Activation Energy ◽  
Nonisothermal Crystallization ◽  
Ozawa Equation ◽  
Nonisothermal Crystallization Kinetics ◽  
Kinetics Of ◽  
Pmma Blends ◽  
Pure Pvdf

Background: poly(vinylidene fluoride) PVDF and PVDF/PMMA blends have been investigated with a focus on the crystal structure, immiscibility and mechanical properties. However, few reports were found on the crystallization behaviors of PVDF and PVDF/PMMA blends, especially on crystallization kinetics. The article is to report the research on isothermal and nonisothermal crystallization kinetics for PVDF and PVDF/PMMA blends using differential scanning calorimetry (DSC). Results: Besides crystallization temperature and isothermal crystallization activation energy, the Avrami equation exponent of PVDF in blends decreased compared with pure PVDF. The nonisothermal crystallization kinetics of PVDF and PVDF/PMMA (70:30) blends were investigated by Ozawa equation, Jeziorny method and crystallization rate constant (CRC) in detail. The nonisothermal crystallization energy of pure PVDF and its blends were determined by the Kissinger and Vyazovkin’s method. Conclusion: The nucleation and growth mechanism of PVDF in blends changed compared with pure PVDF. The Ozawa equation is not applicable in nonisothermal crystallization kinetics of PVDF and PVDF/PMMA blends. The decreasing of crystallization ability of PVDF in blends were found and confirmed by CRC and the decline of crystallization rate constant in Jeziorny method. Such is opposite to the results of Kissinger’s and Vyazovkin’s method, chances are that these two methods were not used to calculate the nonisothermal crystallization activation energy where the nucleation process was influenced.

scholarly journals Диэлектрическая релаксация в тонких слоях стеклообразной системы Ge-=SUB=-28.5-=/SUB=-Рb-=SUB=-15-=/SUB=-S-=SUB=-56.5-=/SUB=-

2018 ◽  
Vol 52 (8) ◽  
pp. 912
Author(s):  
Р.А. Кастро ◽  
Н.И. Анисимова ◽  
А.А. Кононов
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Structural Parameters ◽  
Glass Structure ◽  
Relaxation Processes ◽  
Glassy System ◽  
Debye Relaxation ◽  
Molecular Dipole ◽  
Cole Model ◽  
Charged Defects

AbstractThe results of studying dielectric relaxation processes in the Ge_28.5Pb_15S_56.5 glassy system are presented. The existence of the non-Debye relaxation process caused by the distribution of relaxors over the relaxation time according to the Cole–Cole model is revealed. The energy and structural parameters are calculated: the activation energy E _ p = 0.40 eV and the molecular dipole moment μ = 1.08 D. The detected features are explained within the model according to which the chalcogenide-glass structure is a set of dipoles formed by charged defects such as D ^+ and D ^–.

Effect of Hyperbranched Polymer on Crystallization Kinetics of Isotactic Polypropylene

2012 ◽  
Vol 535-537 ◽  
pp. 1142-1145
Author(s):  
Guang Tian Liu ◽  
Jing Lei
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Isotactic Polypropylene ◽  
Isothermal Crystallization ◽  
Hyperbranched Polymer ◽  
Crystallization Rate ◽  
Crystallization Activation Energy ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

In this paper, the isothermal crystallization kinetics of isotactic polypropylene (iPP) and iPP with 5% hyperbranched polymer (HBP) added had been investigated by differential scanning calorimetry (DSC). The results show that a small addition of HBP affects the crystallization behavior of iPP. During isothermal crystallization, the crystallization rate of the blend is higher than those of iPP remarkably. An increase in the Avrami exponent may be attributed to the fractal structure of hyperbranched polymer. The crystallization activation energy is estimated by the Friedman equation, the results show that the activation energy decreases remarkably by addition of HBP and the crystallization rate of the blend is more sensitive to temperature than that of iPP.

Characteristics of non-isothermal crystallization of polypropylene with and without talc

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Carmen Albano ◽  
José Papa ◽  
Miren Ichazo ◽  
Jeanette González ◽  
Carmen Ustariz
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Kinetic Equation ◽  
Crystallization Temperature ◽  
Crystallization Process ◽  
Crystallization Rate ◽  
Crystallization Activation Energy ◽  
Scanning Calorimetry ◽  
Homogeneous Crystallization ◽  
Temperature Crystallization

Abstract The non-isothermal behaviour of crystallization of polypropylene (PP) and its talc-filled composites was investigated by means of differential scanning calorimetry. Different analytical methods were used to describe the crystallization process. According to the behaviour of crystallization temperature, crystallization activation energy and crystallization parameters and coefficient, talc results in an increase in PP crystallization rate and in a decrease in total energy opposing to homogeneous crystallization. Velisaris-Seferis’ kinetic equation was found to describe reasonably well the non-isothermal behaviour of crystallization of PP and its filled composites.

A Reliable Technique for Experimental Evaluation of Crystallization Activation Energy in PCMs

2008 ◽  
Vol 29 (1) ◽  
pp. 41-43 ◽  
Author(s):  
A. Redaelli ◽  
A. Pirovano ◽  
I. Tortorelli ◽  
D. Ielmini ◽  
A. L. Lacaita
Keyword(s):  
Activation Energy ◽  
Experimental Evaluation ◽  
Crystallization Activation Energy ◽  
Reliable Technique
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