Non-isothermal crystallization kinetic studies on amorphous chalcogenide semiconductors

1982 ◽  
Vol 54 (2) ◽  
pp. 163-168 ◽  
Author(s):  
M.F. Kotkata ◽  
E.A. Mahmoud
Keyword(s):  
Isothermal Crystallization ◽  
Crystallization Kinetic ◽  
Kinetic Studies ◽  
Amorphous Chalcogenide ◽  
Chalcogenide Semiconductors

Non-isothermal crystallization kinetic studies on MgO–Al2O3–SiO2–TiO2 glass

2007 ◽  
Vol 353 (24-25) ◽  
pp. 2383-2391 ◽  
Author(s):  
A. Goel ◽  
E.R. Shaaban ◽  
F.C.L. Melo ◽  
M.J. Ribeiro ◽  
J.M.F. Ferreira
Keyword(s):  
Isothermal Crystallization ◽  
Crystallization Kinetic ◽  
Kinetic Studies

scholarly journals Non-Isothermal Crystallization Kinetic of Polyethylene/Carbon Nanotubes Nanocomposites Using an Isoconversional Method

2019 ◽  
Vol 3 (1) ◽  
pp. 21 ◽  
Author(s):  
Beatriz Menezes ◽  
Tiago Campos ◽  
Thais Montanheiro ◽  
Renata Ribas ◽  
Luciana Cividanes ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Kinetic Parameters ◽  
Isothermal Crystallization ◽  
Crystallization Kinetic ◽  
Model Fitting ◽  
Kinetic Studies ◽  
Isoconversional Method ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Crystallite Sizes

Behavior studies of thermoplastic polymers during non-isothermal crystallization are extremely important since most of their properties are influenced by degree of crystallinity and the crystallization process. In general, an approach based on a model-fitting method is used to perform crystallization kinetic studies. Due to their inability to uniquely determine the reaction mode, many studies have used the isoconversional method, where it is not necessary to assume a crystallization model to obtain the kinetic parameters. Therefore, in this work, the influence of acid and octadecylamine functionalized carbon nanotubes (CNTs) in the crystallization kinetic of polyethylene (PE) was studied using an isoconversional method with differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The kinetic parameters and the crystallization model were determined. The incorporation of functionalized and non-functionalized CNTs into PE did not change the Johnson-Mehl-Avrami crystallization model. However, the CNTs increased the crystallization temperature and reduced the activation energy for crystallization. In addition, the Avrami coefficient values were lower for the nanocomposites when compared to pure PE. The incorporation of CNTs accelerated the crystallization of PE, reducing the crystallite sizes and modifying their morphology.

Study on Non-Isothermal Crystallization Kinetic of Tundish Covering Fluxes

2011 ◽  
Vol 266 ◽  
pp. 102-105
Author(s):  
Li Feng Sun ◽  
Hong Po Wang ◽  
Chun Lai Liu ◽  
Yong Zou ◽  
Mao Fa Jiang
Keyword(s):  
Isothermal Crystallization ◽  
Heat Insulation ◽  
Crystallization Kinetic ◽  
Avrami Equation ◽  
Crystallization Time ◽  
Resistance Furnace ◽  
Crystallization Behaviors ◽  
Good Heat ◽  
Casting Production ◽  
Electrical Resistance Furnace

Basic tundish covering flux is widely used in continuous casting production of high quality steel because of good heat insulation function and the properties of absorbing inclusions. However, there is a serious problem of incrustation caused by basic tundish covering flux in process of pouring and it could be dramatically influenced by the crystallization behaviors of covering flux. In the paper, the crystallization time and ratio of basic tundish covering fluxes were investigated by high temperature electrical resistance furnace and single hot thermocouple apparatus. Based on the crystallization kinetic knowledge and experimental results, Avrami equation was modified, the non-isothermal crystallization equation that could quantitatively describe the crystallization behaviors of basic tundish covering fluxes was established.

scholarly journals The effect of hydroxyapatite nanoparticles on crystallization and thermomechanical properties of PLLA matrix

2017 ◽  
Vol 89 (1) ◽  
pp. 125-140 ◽  
Author(s):  
Ioanna-Georgia I. Athanasoulia ◽  
Maximos N. Christoforidis ◽  
Dimitrios M. Korres ◽  
Petroula A. Tarantili
Keyword(s):  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Crystallization Kinetic ◽  
Crystallization Rate ◽  
Melting Behavior ◽  
Thermomechanical Properties ◽  
Cold Crystallization ◽  
Crystallization Experiments ◽  
Twin Screw

AbstractIn this study, hydroxyapatite (HA) was incorporated in a poly(L-lactic acid) (PLLA) matrix and the thermal properties and crystallization behavior of the derived composites were investigated. The nanocomposites, containing 0–20 wt% HA, were prepared by melt extrusion employing a twin-screw extruder. XRD experiments verified an increase in the intensity of the characteristic diffraction peak of the α-form crystalline phase of PLLA with increasing HA content. By DSC experiments it was observed that the presence of HA increased the crystallinity during cold crystallization, leading to a shift of cold-crystallization temperature to lower values and to an increase in the melting temperature of the PLLA phase. Isothermal crystallization experiments at 100, 110, 115 and 120°C, revealed a maximum in crystallization kinetic around 100°C after the addition of HA compared to 115°C for pure PLLA. The crystallization rate of PLLA matrix in the nanocomposites decreased with increasing crystallization temperature. By using the Avrami and Lauritzen-Hoffman equations the exponent n was calculated in the range 2–3 and a theoretical approach verified that the HA/PLLA systems belong to Regime II of crystallization behavior. The investigated melting behavior of PLLA was attributed to better organized crystalline structure with increasing isothermal crystallization temperatures and might be related with the longer time necessary for the completion of crystallization.

Crystallization kinetic studies: A means to evaluate time-temperature-transformation curves. Application to metallic glasses

1991 ◽  
Vol 37 (6) ◽  
pp. 1261-1268 ◽  
Author(s):  
M. T. Clavaguera-Mora ◽  
S. Suriñach ◽  
M. D. Baró ◽  
S. Bordas ◽  
N. Clavaguera
Keyword(s):  
Metallic Glasses ◽  
Crystallization Kinetic ◽  
Kinetic Studies ◽  
Temperature Transformation

Non-isothermal crystallization behavior of polypropylene/zinc oxide composites

2016 ◽  
Vol 23 (5) ◽  
pp. 505-510 ◽  
Author(s):  
Jianqiang Fang ◽  
Minghua Lang ◽  
Xuchu Ye ◽  
Wei Zhang ◽  
Kongjun Zhu
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Crystallization Kinetic ◽  
Exothermic Peak ◽  
Crystallization Time ◽  
Scanning Calorimetry ◽  
Relative Crystallinity ◽  
Oxide Composites

AbstractThe non-isothermal crystallization behavior of polypropylene (PP)/zinc oxide composites with various mass ratios was investigated by differential scanning calorimetry. The Jeziorny and Mo models were applied to calculate the non-isothermal crystallization kinetic parameters of the composites. During non-isothermal crystallization, the width of the exothermic peak increased from 7°C to 12°C with increasing cooling rate. The exothermic peak position at 10°C shifted to a lower temperature, and the half crystallization time t1/2 decreased from 2.86 min to 0.51 min. The Friedman model was used to determine the variation of activation energy at each stage of crystallization. The crystallization activation energies obtained varied significantly at each stage of crystallization. The crystallization activation energy of PP was -126.8 kJ/mol at 70% relative crystallinity but reached -232.8 kJ/mol at 10% relative crystallinity.

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