Kinetics of non-isothermal crystallization process and activation energy for crystal growth in amorphous materials

1984 ◽  
Vol 19 (1) ◽  
pp. 291-296 ◽  
Author(s):  
Kazumasa Matusita ◽  
Takayuki Komatsu ◽  
Ryosuke Yokota
Keyword(s):  
Activation Energy ◽  
Crystal Growth ◽  
Isothermal Crystallization ◽  
Amorphous Materials ◽  
Crystallization Process ◽  
Kinetics Of

scholarly journals Non-Isothermal Crystallization Kinetics of Poly(Ethylene Glycol)–Poly(l-Lactide) Diblock Copolymer and Poly(Ethylene Glycol) Homopolymer via Fast-Scan Chip-Calorimeter

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1156
Author(s):  
Dejia Chen ◽  
Lisha Lei ◽  
Meishuai Zou ◽  
Xiaodong Li
Keyword(s):  
Ethylene Glycol ◽  
Heterogeneous Nucleation ◽  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Poly Ethylene Glycol ◽  
Ozawa Method ◽  
Isothermal Crystallization Kinetics ◽  
Fast Cooling ◽  
Poly Ethylene ◽  
Kinetics Of

The non-isothermal crystallization kinetics of double-crystallizable poly(ethylene glycol)–poly(l-lactide) diblock copolymer (PEG-PLLA) and poly(ethylene glycol) homopolymer (PEG) were studied using the fast cooling rate provided by a Fast-Scan Chip-Calorimeter (FSC). The experimental data were analyzed by the Ozawa method and the Kissinger equation. Additionally, the total crystallization rate was represented by crystallization half time t1/2. The Ozawa method is a perfect success because secondary crystallization is inhibited by using fast cooling rate. The first crystallized PLLA block provides nucleation sites for the crystallization of PEG block and thus promotes the crystallization of the PEG block, which can be regarded as heterogeneous nucleation to a certain extent, while the method of the PEG block and PLLA block crystallized together corresponds to a one-dimensional growth, which reflects that there is a certain separation between the crystallization regions of the PLLA block and PEG block. Although crystallization of the PLLA block provides heterogeneous nucleation conditions for PEG block to a certain extent, it does not shorten the time of the whole crystallization process because of the complexity of the whole crystallization process including nucleation and growth.

Non-isothermal crystallization and thermal degradation kinetics of MXene/linear low-density polyethylene nanocomposites

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 373-381 ◽  
Author(s):  
Xinxin Cao ◽  
Mengqi Wu ◽  
Aiguo Zhou ◽  
You Wang ◽  
Xiaofang He ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
Isothermal Crystallization ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Kinetics Of

AbstractA novel two-dimensional material MXene was used to synthesize nanocomposites with linear low-density polyethylene (LLDPE). The influence of MXene on crystallization and thermal degradation kinetics of LLDPE was investigated. Non-isothermal crystallization kinetics was investigated by using differential scanning calorimetry (DSC). The experimental data was analyzed by Jeziorny theory and the Mo method. It is found that MXene acted as a nucleating agent during the non-isothermal crystallization process, and 2 wt% MXene incorporated in the nanocomposites could accelerate the crystallization rate. Findings from activation energy calculation for non-isothermal crystallization came to the same conclusion. Thermal gravity (TG) analysis of MXene/LLDPE nanocomposites was conducted at different heating rates, and the TG thermograms suggested the nanocomposites showed an improvement in thermal stability. Apparent activation energy (Ea) of thermal degradation was calculated by the Kissinger method, and Ea values of nanocomposites were higher than that of pure LLDPE. The existence of MXene seems to lead to better thermal stability in composites.

Morphology, Crystalline Structure and Isothermal Crystallization Kinetics of Polybutylene Terephthalate/Montmorillonite Nanocomposites

2005 ◽  
Vol 13 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Defeng Wu ◽  
Chixing Zhou ◽  
Xie Fan ◽  
Dalian Mao ◽  
Zhang Bian
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Polymer Chains ◽  
Isothermal Crystallization Kinetics ◽  
Clay Particles ◽  
Nucleation Sites ◽  
Kinetics Of ◽  
Montmorillonite Nanocomposites

The melt intercalation method was employed to prepare poly(butylene terepathalate)/montmorillonite nanocomposites, and their microstructure was characterized by wide angle X-ray diffraction and transmission electron microscopy. The XRD results showed that the crystalline plane such as (010), (111), (100) was smaller than that of pristine PBT, which indicates that the crystallite size of PBT in the nanocomposites could be diminished by adding clay. Moreover, the isothermal crystallization kinetics of PBT and PBT/MMT nanocomposites was investigated by differential scanning calorimetry (DSC). During isothermal crystallization, the development of crystallinity with time was analysed by the Avrami equation. The results show that very small amounts of clay dramatically increased the rate of crystallization and high clay concentrations reduced the rate of crystallization at the low crystallization temperatures. At low concentrations of clay, the distance between dispersed platelets was large so it was relatively easy for the additional nucleation sites to incorporate surrounding polymer, and the crystal nucleus was formatted easily. However, at high concentrations of clay, the diffusion of polymer chains to the growing crystallites was hindered by large clay particles, despite the formation of additional nucleation sites by the clay layers. At the higher crystallization temperature, the crystallization of the nanocomposites was slower than that of the pure PBT under the experimental conditions, which means that with the increase in chains mobility at the high crystallization temperature, the crystal nuclei are harder to format, and the hindering effect of clay particles on the polymer chains was stronger than the nucleating effect of the layers. In addition, the activation energies of crystallization for PBT and its nanocomposites were calculated by the Arrhenius relationship, and the results showed that the nanocomposites with a low clay content had the lower activation energy values than PBT, while high amounts of clay increased the activation energy of PBT.

Non-Isothermal Crystallization Kinetics of Mg61Zn35Ca4 Glassy Alloy

2017 ◽  
Vol 898 ◽  
pp. 657-665
Author(s):  
Dao Zhang ◽  
Wang Shu Lu ◽  
Xiao Yan Wang ◽  
Sen Yang
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Melt Spinning ◽  
Glassy Alloy ◽  
Heating Rates ◽  
Isothermal Crystallization Kinetics ◽  
Complex Process ◽  
Activation Energy Of Crystallization ◽  
Kinetics Of

The non-isothermal crystallization kinetics of Mg61Zn35Ca4 glassy alloy prepared via melt-spinning were studied by using isoconversion method. The crystalline characterization of Mg61Zn35Ca4 was examined by X-ray diffraction. Different scanning calorimeter was used to investigate the non-isothermal crystallization kinetics at different heating rates (3-60 K/min). The calculated value of Avrami exponent obtained by Matusita method indicated that the crystalline transformation for Mg61Zn35Ca4 is a complex process of nucleation and growth. The Kissinger-Akahira-Sunose method was used to investigate the activation energy. The activation energy of crystallization varies with the extent of crystallization and hence with temperature. The Sestak-Berggren model was used to describe the non-isothermal crystallization kinetics.

scholarly journals Kinetic Processes in Amorphous Materials Revealed by Thermal Analysis: Application to Glassy Selenium

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2725 ◽  
Author(s):  
Málek ◽  
Svoboda
Keyword(s):  
Activation Energy ◽  
Crystal Growth ◽  
Viscous Flow ◽  
Structural Relaxation ◽  
Amorphous Materials ◽  
Supercooled Liquid ◽  
Thermomechanical Analysis ◽  
Growth Data ◽  
Scanning Calorimetry ◽  
Kinetic Processes

It is expected that viscous flow is affecting the kinetic processes in a supercooled liquid, such as the structural relaxation and the crystallization kinetics. These processes significantly influence the behavior of glass being prepared by quenching. In this paper, the activation energy of viscous flow is discussed with respect to the activation energy of crystal growth and the structural relaxation of glassy selenium. Differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and hot-stage infrared microscopy were used. It is shown that the activation energy of structural relaxation corresponds to that of the viscous flow at the lowest value of the glass transition temperature obtained within the commonly achievable time scale. The temperature-dependent activation energy of crystal growth, data obtained by isothermal and non-isothermal DSC and TMA experiments, as well as direct microscopic measurements, follows nearly the same dependence as the activation energy of viscous flow, taking into account viscosity and crystal growth rate decoupling due to the departure from Stokes–Einstein behavior.

Kinetics of non-isothermal crystallization process in various sized Li2B4O7 glasses

2004 ◽  
Vol 131 (2) ◽  
pp. 129-133 ◽  
Author(s):  
S.J. Kim ◽  
J.E. Kim ◽  
Y.H. Rim ◽  
Y.S. Yang
Keyword(s):  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Kinetics Of

Crystal Growth in Amorphous Binary Alloys of Zr-Ni System

2007 ◽  
Vol 26-28 ◽  
pp. 675-678 ◽  
Author(s):  
Takeshi Fukami ◽  
I. Noda ◽  
M. Asada ◽  
D. Okai ◽  
T. Yamasaki
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Crystal Growth ◽  
Crystallization Process ◽  
Isothermal Annealing ◽  
Binary Alloys ◽  
Isothermal Condition ◽  
Amorphous State ◽  
Dta Curves

A crystallization process in an amorphous state under isothermal condition is examined for binary alloys ZrNi and ZrNi2 by differential thermal analysis (DTA). Time dependence of DTA curves is measured at several constant temperatures just below crystallization temperature. The fraction of crystallized volume in amorphous state and its time evolution during isothermal annealing are measured. These data are analyzed by the Johnson-Mehl–Avrami formula. The Avrami exponent is 2.4±0.1 for ZrNi and 3~4 depending on the set temperature for ZrNi2. The activation energy for crystallization of amorphous ZrNi and ZrNi2 was estimated by plots of lnt1/2 vs. 1/T.

scholarly journals EXPOENTE DE AVRAMI PELA EQUAÇÃO DE JMAK PARA MÉTODO NÃO-ISOTÉRMICO DE ANÁLISE TÉRMICA

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Salmo Moreira Sidel ◽  
Elio Idalgo ◽  
Keizo Yukimitu ◽  
João Carlos Silos Moraes ◽  
Fabio Alencar Dos Santos
Keyword(s):  
Crystal Growth ◽  
General Theory ◽  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Nucleation Process ◽  
Vitreous System ◽  
Isothermal Measurements ◽  
Dimensional Crystal

This work reports a discussion about of the general theory for phase transformations of Melh-Johnson-Avrami-Kolmogorov in process involving non-isothermal crystallization. This model allows determine as occurs the mechanism of the nucleus formation and of growth of crystalline phases during the crystallization process. To demonstrate the validity this theory, the Avrami exponent (n) of the LiO2-TeO2-WO3 vitreous system was determined from DSC non-isothermal measurements. The obtained results indicate that the nucleation process is volumetric with two-dimensional or three-dimensional crystal growth. DOI: http://dx.doi.org/10.30609/JETI.2018-2.5566

A NEW METHOD FOR SUPERSATURATION MEASUREMENT: IDEA, IMPLEMENTATION AND RESULTS

2002 ◽  
Vol 16 (01n02) ◽  
pp. 391-398 ◽  
Author(s):  
M. LÖFFELMANN ◽  
A. MERSMANN
Keyword(s):  
Crystal Growth ◽  
Physical Properties ◽  
Crystallization Process ◽  
Measurement Methods ◽  
Time Dependent ◽  
Sensor Surface ◽  
Dependent Development ◽  
Starting Time ◽  
Metastable Zone ◽  
Kinetics Of

Up to now supersaturation measurement can be generalized as using physical properties that show a dependence on concentration as measurands for supersaturation. Impurities, foreign particles or ions influence the metastable zone width as well as the kinetics of nucleation and crystal growth, but most of the existing measurement methods are not able to incorporate those disturbances in the measured supersaturation. Therefore, a supersaturation sensor considering the actual crystallization process itself has been developed. The idea of the new supersaturation sensor is to induce crystallization on the sensor surface by generating an additional supersaturation by cooling and to observe the time-dependent development of the incrustation. Assuming a constant cooling rate and constant properties of the sensor surface the starting time of the incrustation on the sensor surface depends only on the prevailing supersaturation in the process solution. Experimental results obtained for inorganic ( KNO 3) and organic (Adipicacid) crystallizing solutes proved the applicability of the new sensor.

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.

Sign in / Sign up

Export Citation Format

Share Document