Origin of Morphology Change and Effect of Crystallization Time and Si/Al Ratio during Synthesis of Zeolite ZSM‐5

The shear-induced and cellulose-nanofiber nucleated crystallization of two novel aliphatic–aromatic copolyesters is outlined due to its significance for the in situ generation of biodegradable nanocomposites, which require the crystallization of nanofibrous sheared inclusions at higher temperatures. The shear-induced non-isothermal crystallization of two copolyesters, namely, poly(butylene adipate-co-succinate-co-glutarate-co-terephthalate) (PBASGT) and poly(butylene adipate-co-terephthalate) (PBAT), was studied following a light depolarization technique. To have a deep insight into the process, the effects of the shear rate, shear time, shearing temperature and cooling rate on the initiation, kinetics, growth and termination of crystals were investigated. Films of 60 μm were subjected to various shear rates (100–800 s−1) for different time intervals during cooling. The effects of the shearing time and increasing the shear rate were found to be an elevated crystallization temperature, increased nucleation density, reduced growth size of lamella stacks and decreased crystallization time. Due to the boosted nucleation sites, the nuclei impinged with each other quickly and growth was hindered. The effect of the cooling rate was more significant at lower shear rates. Shearing the samples at lower temperatures, but still above the nominal melting point, further shifted the non-isothermal crystallization to higher temperatures. As a result of cellulose nanofibers’ presence, the crystallization of PBAT, analyzed by DSC, was shifted to higher temperatures.

Download Full-text

Synthesis and characterization of analcime (ANA) zeolite using a kaolinitic rock

Scientific Reports ◽

10.1038/s41598-021-92862-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Daniela Novembre ◽

Domingo Gimeno

Keyword(s):

Ambient Pressure ◽

Added Value ◽

Emission Spectrometry ◽

Quantitative Phase Analysis ◽

Crystallization Time ◽

Experimental Protocol ◽

Economic Point ◽

Cell Parameters ◽

Synthesis Protocol

AbstractAnalcime is nowadays an important component in dental porcelain systems, in heterogeneous catalysis, in the nanoelectronic field, in selective adsorption and in stomatology (dental filling and prosthesis). Analcime synthesis from an impure, silica-rich kaolinite rock coming from Romana (Sassari, Italy) is here presented. A synthesis protocol is proposed that aims to make an improvement of synthesis conditions compared to the past. The hydrothermal treatment is in fact here achieved without aging times and without the use of sodium silicate or other additional silica source reported in the literature. Lower calcination temperature, synthesis temperature and crystallization time are verified in this work. The kaolin is subjected to calcination at the temperature of 650 °C and then mixed with NaOH. The experiment is performed at ambient pressure and 170 ± 0.1 °C. The degree of purity of analcime is calculated in 97.57% at 10 h. Analcime is characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry and thermal analysis. Density is also calculated. Cell parameters and the amount of amorphous phase in the synthesis powders is estimated with quantitative phase analysis using the combined Rietveld and reference intensity ratio methods. The experimental conditions make the synthesis protocol particularly attractive from an economic point of view. Also this work does not use a commercial kaolin but silica-rich impure kaolinitic rock from a disused quarry. This further reduces the costs of the experimental protocol. It also gives the protocol an added value, as the synthesis of a useful mineral is obtained through the valorization of an otherwise unused georesource. Both chemical and physical characterization of analcime is satisfactory making the experimental protocol very promising for an industrial transfer.

Download Full-text

Study on Non-Isothermal Crystallization Kinetic of Tundish Covering Fluxes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.266.102 ◽

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.

Download Full-text

Beach Morphology Change Caused by Overwash on Yokosuka Coast

PROCEEDINGS OF COASTAL ENGINEERING JSCE ◽

10.2208/proce1989.54.681 ◽

2007 ◽

Vol 54 ◽

pp. 681-685

Author(s):

Xuan Tinh NGUYEN ◽

Hitoshi TANAKA

Keyword(s):

Beach Morphology ◽

Morphology Change

Download Full-text

A designed mutant of the enzyme glutathione reductase shortens the crystallization time by a factor of forty

Acta Crystallographica Section D Biological Crystallography ◽

10.1107/s090744499300993x ◽

1994 ◽

Vol 50 (2) ◽

pp. 228-231 ◽

Cited By ~ 7

Author(s):

P. R. E. Mittl ◽

A. Berry ◽

N. S. Scrutton ◽

R. N. Perham ◽

G. E. Schulz

Keyword(s):

Glutathione Reductase ◽

Crystallization Time

Download Full-text

First-principle atomistic thermodynamic study on the early-stage corrosion of NiCr alloy under fluoride salt environment

Physical Chemistry Chemical Physics ◽

10.1039/c8cp05045g ◽

2018 ◽

Vol 20 (45) ◽

pp. 28832-28839 ◽

Cited By ~ 2

Author(s):

Ya-Ru Yin ◽

Cui-Lan Ren ◽

Han Han ◽

Jian-Xing Dai ◽

Hao Wang ◽

...

Keyword(s):

Ab Initio ◽

Early Stage ◽

Thermodynamic Study ◽

Thermodynamic Method ◽

Alloy Surface ◽

First Principle ◽

Fluoride Salt ◽

Nicr Alloy ◽

Morphology Change

The atomic morphology change in the NiCr alloy surface induced by fluorine-chemisorption was investigated by the ab initio atomistic thermodynamic method to elucidate early-stage corrosion processes of nickel-based alloys in strong oxidizing environment.

Download Full-text

Kinetics of crystallization for polypropylene/polyethylene/halloysite nanotube nanocomposites

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705718807953 ◽

2018 ◽

Vol 33 (4) ◽

pp. 451-463 ◽

Cited By ~ 6

Author(s):

MY Ong ◽

WS Chow

Keyword(s):

Crystallization Rate ◽

Avrami Equation ◽

Crystallization Time ◽

Halloysite Nanotube ◽

Kissinger Equation ◽

Polyethylene Blends ◽

Instantaneous Nucleation ◽

Half Crystallization Time ◽

T Values ◽

Kinetics Of

The aim of this study is to investigate the kinetics of non-isothermal crystallization of polypropylene/high-density polyethylene/halloysite nanotube (PP/HDPE/HNT) nanocomposites using three methods, that is, Avrami equation, combined Ozawa–Avrami method (hereafter called Mo model), and Kissinger equation. The Avrami exponent ( n) is in the range of 1–2 for all the PP/HDPE/HNT nanocomposites indicating instantaneous nucleation while the crystallization rate constant ( Zt) values of PP/HDPE increased with the addition of HNT. This proved that addition of HNT increases the crystallization rate. The reduction of half crystallization time ( t 1/2) for PP/HDPE as the increasing HNT loading indicates faster crystallization rate. In the Mo model, the cooling rate chosen at unit crystallization time F( T) values for PP/HDPE decreases with the addition of HNT. Kissinger equation showed that the activation energy ( E a) of crystallization for the PP/HDPE decreases with the addition of HNT. All the results demonstrated that HNT can accelerate the crystallization rate for the PP/polyethylene blends.

Download Full-text

Melt Crystallization Behavior and Crystalline Morphology of Polylactide/Poly(ε-caprolactone) Blends Compatibilized by Lactide-Caprolactone Copolymer

Polymers ◽

10.3390/polym10111181 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1181 ◽

Cited By ~ 7

Author(s):

Chunmei Zhang ◽

Qiaofeng Lan ◽

Tianliang Zhai ◽

Shengqiang Nie ◽

Jun Luo ◽

...

Keyword(s):

Crystallization Behavior ◽

Crystallization Time ◽

Half Time ◽

Melt Crystallization ◽

Crystalline Morphology ◽

Casting Method ◽

Three Samples ◽

Significant Difference ◽

Compatibilization Effect ◽

Kinetics Of

Lactide-Caprolactone copolymer (LACL) was added to a Polylactide/Poly(ε-caprolactone) (PLA/PCL) blend as a compatibilizer through solution mixing and the casting method. The melt crystallization behavior and crystalline morphology of PLA, PLA/PCL, and PLA/PCL/LACL were investigated using differential scanning calorimeter (DSC) and polarized optical microscopy (POM), respectively. The temperature of the shortest crystallization time for the samples was observed at 105 °C. The overall isothermal melt crystallization kinetics of the three samples were further studied using the Avrami theory. Neat PLA showed a higher half-time of crystallization than that of the PLA/PCL and PLA/PCL/LACL blends, whereas the half-time of crystallization of PLA/PCL and PLA/PCL/LACL showed no significant difference. The addition of PCL decreased the spherulite size of crystallized PLA, and the nuclei density in the PLA/PCL/LACL blend was much higher than that of the PLA and PLA/PCL samples, indicating that LACL had a compatibilization effect on the immiscible PLA/PCL blend, thereby promoting the nucleation of PLA. The spherulites in the PLA/PCL and PLA/PCL/LACL blend exhibited a smeared and rough morphology, which can be attributed to the fact that PCL molecules migrated to the PLA spherulitic surface during the crystallization of PLA.

Download Full-text