Effect of the nucleation mechanism on complex poly(L-lactide) nonisothermal crystallization process. Part 1: Thermal and structural characterization

2011 ◽  
Vol 121 (6) ◽  
pp. 3368-3376 ◽  
Author(s):  
Andrea Martinelli ◽  
Massimo Calì ◽  
Lucio D'Ilario ◽  
Iolanda Francolini ◽  
Antonella Piozzi
Keyword(s):  
Structural Characterization ◽  
Crystallization Process ◽  
Nucleation Mechanism ◽  
Nonisothermal Crystallization

scholarly journals Mechanism and Modelling of Reactive Crystallization Process of Lithium Carbonate

Processes ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 248 ◽  
Author(s):  
Shaolei Zhao ◽  
Jie Gao ◽  
Siyang Ma ◽  
Chao Li ◽  
Yiming Ma ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Induction Time ◽  
Crystallization Process ◽  
Dominant Role ◽  
Lithium Carbonate ◽  
Nucleation Mechanism ◽  
Lithium Sulfate ◽  
Laser Method ◽  
Reactive Crystallization

The reactive crystallization of lithium carbonate (Li2CO3) from lithium sulfate (Li2SO4) and sodium carbonate (Na2CO3) solutions is a key process in harvesting solid lithium, whether from ores, brines, or clays. However, the process kinetics and mechanism remain poorly understood and the modelling of the reactive crystallization of Li2CO3 is not available. Hence, this work aims to determine the kinetics and mechanisms of the nucleation and growth of Li2CO3 reactive crystallization by induction time measurements and to model and optimize the crystallization process using response surface methodology. Induction time measurements were carried out as functions of initial supersaturation and temperature using a laser method. It was found that the primary nucleation mechanism of Li2CO3 varies with solution supersaturations, in which, expectedly, the heterogenous nucleation mechanism dominates at low supersaturations while the homogeneous nucleation mode governs at high supersaturations. The transition point between heterogenous and homogenous nucleation was found to vary with temperatures. Growth modes of Li2CO3 crystals were investigated by relating induction time data with various growth mechanisms, revealing a two-dimensional nucleation-mediated growth mechanism. The modelling and optimization of a complex reactive crystallization were performed by response surface methodology (RSM), and the effects of various crystallization parameters on product and process performances were examined. Solution concentration was found to be the critical factor determining the yield of crystallization, while stirring speed was found to play a dominant role in the particle size of Li2CO3 crystals. Our findings may provide a better understanding of the reactive crystallization process of Li2CO3 and are critical in relation to the crystallization design and control of Li2CO3 production from lithium sulfate sources.

Study on the nonisothermal crystallization process of mLLDPE/EVA blends using FTIR micro-spectroscopy

2005 ◽  
Vol 96 (2) ◽  
pp. 261-267 ◽  
Author(s):  
Tong Wu ◽  
Ying Li ◽  
Qiang Wu ◽  
Gang Wu ◽  
Hui-Min Tan
Keyword(s):  
Crystallization Process ◽  
Nonisothermal Crystallization

Study on Non-Isothermal Crystallization Kinetics of PBT with High Melt Flow Index

2012 ◽  
Vol 487 ◽  
pp. 58-63 ◽  
Author(s):  
Qing Yan Xu ◽  
Lin Wang ◽  
Yuan Liu ◽  
Zhi Hong Guo ◽  
Pei Jie Lin ◽  
...  
Keyword(s):  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Melt Flow Index ◽  
Flow Index ◽  
Melt Flow ◽  
Nonisothermal Crystallization ◽  
Isothermal Crystallization Kinetics ◽  
Avrami Index ◽  
Ozawa Equation ◽  
Kinetics Of

The non-isothermal crystallization process of PBT with high melt flow index has been investigated by DSC, and the nonisothermal crystallization process of PBT with high melt flow index was studied by Ozawa equation and Jeziorny equation respectively. It was found that Ozawa equation, rather than Jeziorny equation, could appropriately be applied to study the non-isothermal crystallization process of PBT with high melt flow index. The Avrami index, obtained by Ozawa equation, varied between 1.06-1.80 with the change in temperature.

scholarly journals Effects of Soybean Oil Modified Cellulose Fibril and Organosilane Modified Cellulose Fibril on Crystallization of Polypropylene

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Sarit Thanomchat ◽  
Kawee Srikulkit
Keyword(s):  
Soybean Oil ◽  
Crystallization Process ◽  
Optical Microscope ◽  
Particle Dispersion ◽  
Melt Mixing ◽  
Nonisothermal Crystallization ◽  
Cellulose Fibril ◽  
Crystallization Study ◽  
Modified Cellulose ◽  
Composite Samples

Soybean oil modified cellulose fibril (Oil-g-CF) and organosilane modified cellulose fibril (Silane-g-CF) were prepared using maleinized soybean oil and hexadecyltrimethoxysilane, respectively. Thus obtained modified cellulose fibril was added to polypropylene by a simple melt mixing on a hotplate. PP/modified CF composites with 4.0 wt% filler content were prepared. The composites were subject to a polarized optical microscope to investigate particle dispersion, supramolecular morphology, and crystallization behavior. It was found that Silane-g-CF exhibited smaller particle sizes with better particle distribution when compared to Oil-g-CF. In addition, the etched composite samples unveiled an increase in a number of spherulite crystals as well as a decrease in the spherulite size. The nonisothermal crystallization study of composites revealed that both Oil-g-CF and Silane-g-CF were capable of nucleating PP by facilitating faster crystallization process and raising the number of spherulites. The DSC results indicated that Silane-g-CF was able to perform a more effective nucleation than Oil-g-CF, judged by a higher crystallization temperature. Moreover, PP composites containing Oil-g-CF and Silane-g-CF had higher crystallinity by 7% and 10%, for the first and the latter, respectively, when compared to neat PP.

Nonisothermal crystallization kinetics of polybutene-1 containing nucleating agent with acid amides structure

2014 ◽  
Vol 34 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Yongxian Zhao ◽  
Junyi Chen ◽  
Lei Han ◽  
Le Zhao
Keyword(s):  
Crystallization Process ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Mass Ratio ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Nucleation Effect ◽  
Activation Energy Of Crystallization ◽  
Nonisothermal Crystallization Kinetics ◽  
Kinetics Of

Abstract The nonisothermal crystallization behaviors of virgin isotactic polybutene-1 (iPB-1) and iPBn (iPB-1 containing a nucleating agent that owns acid amides structure; iPB/Mult920=100/0.5, mass ratio) were studied by means of differential scanning calorimetry (DSC). Modified Avrami theories (Ozawa method) and Mo method were used to analyze the DSC date. The results show that both methods are suitable to describe the crystallization process of iPB-1 and iPBn. Addition of 0.5% (mass ratio) nucleating agent can give rise to the nucleation effect, which increases the crystallization temperature (Tc) and the rate of crystallization of iPB-1, decreases the activation energy of crystallization (ΔE), and increases the crystallization rate of iPB-1 under the actual conditions.

Phase behavior of cationic and anionic surfactants at low concentrations

1992 ◽  
Vol 50 (1) ◽  
pp. 694-695
Author(s):  
E. Naranjo
Keyword(s):  
Phase Behavior ◽  
Structural Characterization ◽  
Dynamic Systems ◽  
Anionic Surfactants ◽  
Intermolecular Forces ◽  
Stable Form ◽  
Surfactant Mixtures ◽  
Low Concentrations ◽  
Cationic And Anionic Surfactants ◽  
General Method

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.

New ultrastructural findings about Borrelia burgdorferi by cryofixation, negative staining, thin sectioning and scanning techniques

1990 ◽  
Vol 48 (3) ◽  
pp. 582-583
Author(s):  
S. F. Hayes ◽  
M. D. Corwin ◽  
T. G. Schwan ◽  
D. W. Dorward ◽  
W. Burgdorfer
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Structural Characterization ◽  
Negative Staining ◽  
Low Speed ◽  
Thin Sectioning ◽  
Ultrastructural Findings

Characterization of Borrelia burgdorferi strains by means of negative staining EM has become an integral part of many studies related to the biology of the Lyme disease organism. However, relying solely upon negative staining to compare new isolates with prototype B31 or other borreliae is often unsatisfactory. To obtain more satisfactory results, we have relied upon a correlative approach encompassing a variety EM techniques, i.e., scanning for topographical features and cryotomy, negative staining and thin sectioning to provide a more complete structural characterization of B. burgdorferi.For characterization, isolates of B. burgdorferi were cultured in BSK II media from which they were removed by low speed centrifugation. The sedimented borrelia were carefully resuspended in stabilizing buffer so as to preserve their features for scanning and negative staining. Alternatively, others were prepared for conventional thin sectioning and for cryotomy using modified procedures. For thin sectioning, the fixative described by Ito, et al.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

Raman scattering studies on slow crystallization process from amorphous PbTiO3

1983 ◽  
Vol 44 (11) ◽  
pp. 313-318 ◽  
Author(s):  
Masaaki Takashige ◽  
Terutaro Nakamura ◽  
Yutaka Aikawa
Keyword(s):  
Raman Scattering ◽  
Crystallization Process
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