2 edition of Computer modeling of non-isothermal crystallization found in the catalog.
Computer modeling of non-isothermal crystallization
|Statement||K.F. Kelton ... [et al.].|
|Series||[NASA contractor report] -- 207362, NASA contractor report -- NASA CR-207362.|
|Contributions||Kelton, K. F., United States. National Aeronautics and Space Administration.|
|The Physical Object|
(XPP) model with non-isothermal flow and with the Nakamura equation for crystallization kinetics. The aim of this paper is to verify predicting capabilities of the variational principle based Zatloukal/Vlcek film blowing model, taking non-isothermal processing conditions and non-Newtonian polymer behavior into account, on Tas’s. The isothermal and nonisothermal crystallization kinetics of monoglyceride (MAG) organogels were studied by pulsed nuclear magnetic resonance (pNMR) and differential scanning calorimetry (DSC), respectively. The Avrami equation was used to describe the isothermal crystallization kinetics and experimental data fitted the equation fairly well. Results showed Cited by: 7.
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A realistic computer model for simulating isothermal and non-isothermal phase transformations proceeding by homogeneous and heterogeneous nucleation and interface-limited growth is presented. A new treatment for particle size effects on the crystallization kinetics is developed and is incorporated into the numerical by: Non-isothermal differential scanning calorimetry (DSC) data of electroless nickel–phosphorus (EN) samples with three different phosphorus contents (9, 12 and 16 wt%) has been used in the computer modelling of crystallization kinetics based upon the Johnson–Mehl–Avrami (JMA) by: A realistic computer model for simulating isothermal and non-isothermal phase transformations proceeding by homogeneous and heterogeneous nucleation and interface-limited growth is presented.
A new treatment for particle size effects on the crystallization kinetics is developed and is incorporated into the numerical model. Non-isothermal differential scanning calorimetry (DSC) data of electroless nickel–phosphorus (EN) samples with three different phosphorus contents (9, 12 and 16 wt%) has been used in the computer.
A 3D computer modeling and simulation has been used to predict crystallization kinetics and crystal morphology in polymers under the non-isothermal condition. A parametric study is used to explore the influences of thermal conditions on the by: 7.
This paper is devoted to the study of mathematical problems arising in the modelling of nonisothermal polymer crystallization under industrial conditions.
A review of the hybrid stochastic-deterministic modelling procedure, which yields an averaged model, 5,8 is given and supplied by the study of mathematical problems arising from by: This paper is devoted to the study of mathematical problems arising in the modelling of nonisothermal polymer crystallization under industrial conditions.
A review of the hybrid. Unified isothermal and non-isothermal modelling of neat PEEK crystallization Article (PDF Available) in Journal of Thermal Analysis and Calorimetry (2) February with Reads. A numerical model able to simulate polymer crystallization under nonisothermal flows is developed.
It is based on the assumption that the trace of the extra-stress tensor, calculated according to a. Summary. Recently, Burger and Capasso [M 3 AS 11 () –] derived a coupled system of partial differential equations to describe non-isothermal crystallization of polymers.
The system is based on a spatial averaging of the underlying stochastic birth-and-growth process describing the Computer modeling of non-isothermal crystallization book and growth of single by: 2. This paper is devoted to the study of mathematical problems arising in the modelling of nonisothermal polymer crystallization under industrial conditions.
A review of the hybrid stochastic-deterministic modelling procedure, which yields an averaged model 5;8, is given and supplied by the study of mathematical problems arising from it. A differential generalized Avrami’s law is used to model crystallization kinetic of PEEK in considering that PEEK crystallization results from the contribution of two distinct mechanisms.
The form of this equation allows to predict with good accuracy both isothermal and non-isothermal crystallization kinetics.
Nevertheless, isothermal model parameters are not Cited by: 9. This chapter discusses recent experimental and model developments concerning the influence of industrially relevant cooling rates and pressures on the non-isothermal crystallization of both an isotactic polypropylene and a linear low-density polyethylene by: 1.
Non Isothermal Global Model and Operating Maps 79 Stochastic Global Model 80 PBM comparison 87 Operational Map 93 Solvent-Antisolvent Interactions and Hydrogen Bonding Chapter 6. Conclusions and Future Research Conclusions Future Research Appendix A.
Nomenclature References Non-isothermal crystallization during cooling The main focus of this report is the analysis of heating curves after defined crystallization. But for a better comparison we first mention here additional experimental results measured from cooling at various cooling by: An equation expressing the volume fraction,x, of crystals precipitating in a glass heated at a constant rate, α, was derived.
When crystal particles grow m-dimensionally,x is expressed as In [- ln(1 -x)] = -n (nα - mE/RT + Constant whereE is the activation energy for crystal growth andn is a numerical factor depending on the nucleation process.
When the Cited by: A computer model that al- lows a realistic analysis of these non-isothermal DTA data and an exploration of finite size effects is presented in a companion paper .
Conclusions Acknowledgements In summary, we have demonstrated that glasses heated through a temperature range where there is significant nucleation can develop widely different.
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Modeling of non-isothermal annealing: Interaction of recrystallization, recovery, and precipitation Article in Acta Materialia 59(17) October with 56. Two nonisothermal crystallization models, the Ozawa model and the modified Avrami model, have been evaluated using computer simulation data of nonisothermal crystallization .
In this short communication, the Kissinger model is evaluated using the nonisothermal crystallization data derived from computer simulation. The only comprehensive reference on polymer crystallization, Handbook of Polymer Crystallization provides readers with a broad, in-depth guide on the subject, covering the numerous problems encountered during crystallization as well as solutions to resolve those problems to achieve the desired result.
Edited by leading authorities in the field. isothermal crystallization, is based on rapidly cooling the sample from the melt to the crystallization temperature and then measuring the heat evolved while the sample is held isothermal. The model most often applied to isothermal crystallization data is the Avrami model.
This model, while possessing physically significant parameters, is somewhatFile Size: KB. (Fe40Ni40B19Cu1)97Nb3 magnetic amorphous alloys have been prepared by a melt-spun method, and their crystallization behavior and kinetics have been investigated.
The results showed that under non-isothermal conditions, the growth process is easier than the nucleation process for both precipitated phases ((Fe,Ni)23B6 and γ(Fe,Ni)), and the activation energy Author: Zhe Chen, Qianke Zhu, Kewei Zhang, Yong Jiang.
The isoconversional method, a model-free analysis of the kinetics of liquid−solid transformations, was used to determine the effective activation energy of the nonisothermal crystallization of melts of pure and complex systems of triacylglycerols (TAGs).
The method was applied to data from differential scanning calorimetry (DSC) measurements of the heat of crystallization Cited by: Researchers have sought to study the non-isothermal crystallization of polymers because actual processing conditions in this process are closer to non-isothermal cycles than to isothermal cycles.
Based on Avrami’s model, Jeziorny [ 13 ] established a model that may be applied in the crystallization behavior of polymers at a constant cooling : Jianqiang Fang, Minghua Lang, Xuchu Ye, Wei Zhang, Kongjun Zhu. Isothermal and Non-Isothermal Crystallization Kinetics of Conductive Polyvinylidene Fluoride/Poly(Ethylene Terephthalate) Based Composites.
Nafaa Athmouni, Jianbin Song, Frej Mighri, Saïd Elkoun. Materials Sciences and Applications Vol.7 No Full-Text HTML XML Pub. Date: Janu Nonisothermal crystallization behaviors of nanocomposites prepared by in situ polymerization of high-density polyethylene on tungsten oxide particles.
Macromolecular Research23, DOI: /s Freddy A. Cited by: A non-isothermal Taylor vortex fluid motion was applied for effective control of the crystal size distribution (CSD) in batch cooling crystallization without seed crystals. The non-isothermal Taylor vortex fluid motion was generated using different cylinder temperatures, i.e., a hot inner cylinder and cold outer cylinder, in a Couette–Taylor (CT) by: 1.
Equation  should be a straight line if this model is valid, Z t and n can be determined from the antilogarithmic value of the y-intercept and from the slope, should be noted that Z t and n do not have the same physical meaning as in the original Avrami analysis for isothermal crystallization, because the temperature changes instantly in the non-isothermal process.
A numerical model simulating the crystallization of polymers under nonisothermal flow conditions is presented. Crystallization is described as a spherulitical nucleation and growth process. Two distinct nucleation rates are considered.
The modified Avrami model was found to accurately predict the induction time, maximum phase volume and dimensionality of crystal growth for stearic acid containing molecules when the experimental method employed measures as a function of phase volume.
Four methods were examined to validate the model includinCited by: The crystallization of a model compound, sucrose, from the amorphous solid state has been studied non-isothermally using differential scanning calorimetry to determine crystallization temperature, Tc, and isothermally at 30°C by subjecting samples to % relative humidity and gravimetrically monitoring water vapor uptake and subsequent loss with time due to by: The isothermal and nonisothermal crystallization kinetics of monoglyceride (MAG) organogels were studied by pulsed nuclear magnetic resonance (pNMR) and differential scanning calorimetry (DSC), Avrami equation was used to describe the isothermal crystallization kinetics and experimental data fitted the equation fairly by: 7.
Poly(l-lactic acid) (PLLA) intercalated nanocomposite films containing 1, 2, 5, and 10% organically modified montmorillonite (OMMT) have been synthesized by the solvent casting approach. The thermal characteristics, isothermal cold crystallization kinetics, and structural changes of neat PLLA and its nanocomposites during annealing were studied by using Cited by: The top of crystallization zone is cooling strongly than the bottom, because the intensive heat exchange with air.
Numerical modeling shows that cooling rate is a function of laser power and has a size of order 10 3 - 10 4 K/s. The warmer crystallization zone begins to cool rapidly (cooling rate rises).Author: V. Niziev, F. Mirzade, V. Panchenko, M. Khomenko, R. Grishaev, S.
Pityana, C. Some aspects of nonisothermal crystallization of polymers. Relationship between crystallization temperature, crystallinity, and cooling conditions Jun Zou, Isothermal and non-isothermal crystallization kinetics and predictive modeling in the solidification of poly Jean-Loup Chenot, Jean-Marc Haudin, Semianalytical models to predict Cited by: The crystallization of a glass upon heating can be performed in several ways.
In caloimetric measurements, two basic methods can be used, isothermal and non-isothermal. However, the results of crystallization process can be interpreted in terms of several theoretical models File Size: KB.
The non-isothermal crystallization of the biodegradable poly(4-hydroxybutyrate) (P4HB) has been studied by means of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). In the first case, Avrami, Ozawa, Mo, Cazé, and Friedman methodologies were applied.
The isoconversional approach developed by Vyazovkin allowed also the Author: Ina Keridou, Luis J. del Valle, Lutz Funk, Pau Turon, Lourdes Franco, Jordi Puiggalí.
Jeziorny, A. () Parameters Characterizing the Kinetics of the Non-Isothermal Crystallization of Poly(Ethylene Terephthalate) Determined by DSC. Polymer, 19, The non-isothermal crystallizing data were analyzed with the Avrami, Ozawa and Mo et al.
models and the crystallization parameters of the samples were obtained. It is demonstrated that the combination of the Avrami and Ozawa models developed by Mo et al. was successful in describing the non-isothermal crystallization process for pure PLA and Cited by: 9.
Many solid state transformations follow the Johnson-Mehl-Avrami kinetic equation, particularly crystallization of polymers, glasses and amorphous metals. The value of the Avrami exponent in this relationship, important for understanding the reaction mechanism, is normally determined by isothermal differential scanning calorimetry.
A computer model has been Cited by: The fully implicit finite-difference method is used to solve the continuity, momentum, and energy equations for flow within a gas pipeline.
This methodology (1) incorporates the convective inertia term in the conservation of momentum equation, (2) treats the compressibility factor as a function of temperature and pressure, and (3) considers the friction Cited by: Secondary Nucleation Constant from Non-Isothermal Crystallization.
DSC calorimetric data from non-isothermal crystallization experiments can also be employed to known crystal growth parameters as, for example, the secondary nucleation constant. The Lauritzen–Hoffman model is usually accepted to determine the crystal growth rate, : Ina Keridou, Luis J.
del Valle, Lutz Funk, Pau Turon, Lourdes Franco, Jordi Puiggalí.