Journal articles: 'Cooling crystallization process'

1

Ettouney, R. S., and M. A. El-Rifai. "Indirect Cooling Crystallization Process Analysis." Chemical Engineering Research and Design 85, no. 11 (January 2007): 1476–84. http://dx.doi.org/10.1205/cherd07052.

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Bosq, Nicolas, Nathanaël Guigo, and Nicolas Sbirrazzuoli. "Crystallization Behaviour of Polytetrafluoroethylene over very Large Cooling Rate Domains." Advanced Materials Research 747 (August 2013): 201–4. http://dx.doi.org/10.4028/www.scientific.net/amr.747.201.

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Polytetrafluoroethylene (PTFE) is a semi-crystalline polymer that demonstrates a very fast crystallization process on cooling. This study investigates the nonisothermal PTFE ultra-fast crystallization over a wide range of cooling rates via conventional Differential Scanning Calorimetry (DSC), Fast Scanning Calorimetry (FSC) and Ultra-Fast Scanning Calorimetry (UFSC). A new knowledge about crystallization kinetics of PTFE is obtained from the data obtained under very fast cooling rates. The shift of the melting peak to lower temperature shows that the crystals formed under fast cooling rates are slightly less stable than those produced under slower cooling rates. SEM analysis allows to observe these differences in crystal morphologies. According to the results, the crystallization is still present even for the fastest cooling rate employed and in consequences it is impossible to reach a metastable glassy state. The effective activation energy (Eα) displays a variation with the relative extent of crystallization (α) that is characteristic of a transition of PTFE crystallization from regime II to regime III around 312°C. Following the Hoffman-Lauritzen theory the Eα dependency obtained from the crystallizations under the different cooling rates was fitted in order to study the theoretical dependence of the growth rate.

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Hou, Jianfeng, Kefeng Pan, and Xihan Tan. "Preparation of 6N,7N High-Purity Gallium by Crystallization: Process Optimization." Materials 12, no. 16 (August 10, 2019): 2549. http://dx.doi.org/10.3390/ma12162549.

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In this study, radial crystallization purification method under induction was proposed for preparing 6N,7N ultra-high purity gallium crystal seed. The effect of cooling temperature on the morphology of the crystal seed, as well as the cooling water temperature, flow rate, and the addition amount of crystal seed on the crystallization process was explored, and the best purification process parameters were obtained as follows: temperature of the crystal seed preparation, 278 K; temperature and flow rate of the cooling water, 293 K and 40 L·h−1, respectively; and number of added crystal seed, six. The effects of temperature and flow rate of the cooling water on the crystallization rate were investigated. The crystallization rate decreased linearly with increasing cooling water temperature, but increased exponentially with increasing cooling water flow. The governing equation of the crystallization rate was experimentally determined, and three purification schemes were proposed. When 4N crude gallium was purified by Scheme I, 6N high-purity gallium was obtained, and 7N high-purity gallium was obtained by Schemes II and III. The purity of high-purity gallium prepared by the three Schemes I, II, and III was 99.999987%, 99.9999958%, and 99.9999958%, respectively.

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Dai, Guangming, Lihua Zhan, Chenglong Guan, and Minghui Huang. "The effect of cooling rate on crystallization behavior and tensile properties of CF/PEEK composites." Journal of Polymer Engineering 41, no. 6 (April 14, 2021): 423–30. http://dx.doi.org/10.1515/polyeng-2020-0356.

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Abstract In this study, the differential scanning calorimetry (DSC) tests were performed to measure the nonisothermal crystallization behavior of carbon fiber reinforced polyether ether ketone (CF/PEEK) composites under different cooling rates. The characteristic parameters of crystallization were obtained, and the nonisothermal crystallization model was established. The crystallization temperature range of the material at different cooling rates was predicted by the model. The unidirectional laminates were fabricated at different cooling rates in the crystallization temperature range. The results showed that the crystallization temperature range shifted to a lower temperature with the increase of cooling rate, the established nonisothermal crystallization model was consistent with the DSC test results. It is feasible to shorten the cooling control range from the whole process to the crystallization range. The crystallinity and transverse tensile strength declined significantly with the increase of the cooling rate in the crystallization temperature range. The research results provided theoretical support for the selection of cooling conditions and temperature control range, which could be applied to the thermoforming process of semi-crystalline polymer matrixed composites to improve the manufacturing efficiency.

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Mursalin, Mursalin. "Crystallization Kinetics Of Coconut Oil Based On Gompertz Model." Indonesian Food Science and Technology Journal 1, no. 1 (May 17, 2018): 1–7. http://dx.doi.org/10.22437/ifstj.v1i1.4269.

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The cooling rate and temperature of crystallization has been proven to be very influential on the rate of crystal formation oil. Oil crystallization kinetics can be measured by monitoring changes in the solid fat content(SFC) of oil during cooling process. In this study, SFC measuredusing pulsed Nuclear Magnetic Resonance (pNMR). Four levels of cooling rates and temperature crystallization studied. Crystallization kinetics parameters were measured by applying the model of Gompertz. Gompertz model used to explain the induction time, the increase in the maximum rate of crystallization and the crystalline polymorphic. Crystallization was done by heating the oil at a temperature of 70°C for 10 minutes prior to rapid cooling to 29°C. Then, rate of cooling from 29°C to the crystallization temperature (critical cooling rate) was set below 2°C/minutes. During the process, the oil was stirred at 15 rpm. Solid fraction was measured periodically since the crystallization temperature was reached until maximum solid fraction was achieved. The results showed that the Gompertzmodel able to quantitatively describe the crystallization kinetics of coconut oil. Lower critical cooling rate reduces the induction time of crystallization but accelerate the maximum increase rate of crystallization. Crystallization temperature has a negative correlation with the induction time and the maximum increase rate of crystallization. In the crystallization of coconut oil, critical cooling rate and crystallization temperature are only influence on the thermodynamics and kinetics of crystallization but not on its polymorphic formation.

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Lang, Yi-dong, Arturo M. Cervantes, and Lorenz T. Biegler. "Dynamic Optimization of a Batch Cooling Crystallization Process." Industrial & Engineering Chemistry Research 38, no. 4 (April 1999): 1469–77. http://dx.doi.org/10.1021/ie980585u.

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Qin, Hong Wu, Xiao Xue Xing, and Xian Zhang. "The Analysis for Crystallization of Sn-Pb Alloys Using Acoustic Emission Testing about Wind Turbine Root Materials." Applied Mechanics and Materials 668-669 (October 2014): 83–86. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.83.

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Regular researches of system Sn-Pb alloys with use AE are carried out in various crystallization conditions. In the given researches the technique has been used, which allow to divide the signals radiated with plastic deformation and crack's formation and development from each process. In the metals and alloys majority radiation of AE signals begins in the middle of crystallization's area and comes to an end at the moment of the crystallization termination However in a number of materials AE signals have been registered below an excess point on a cooling curve in a firm condition. Essential influence of small impurity on AE feature and is revealed at crystallization AE character with crystallization of pure metals is defined by a kind of a crystal lattice. Linear dependence total AE from cooling rate is established Influence of superfluous and low residual pressure on AE character established with crystallization.

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Samsuri, Shafirah, Nurul Aini Amran, Loh Jia Zheng, and Muhammad Muhaimin Mohd Bakri. "Effect of coolant temperature and cooling time on fractional crystallization of biodiesel and glycerol." Malaysian Journal of Fundamental and Applied Sciences 13, no. 4 (December 26, 2017): 676–79. http://dx.doi.org/10.11113/mjfas.v13n4.925.

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In the middle of the era of technology and fast-growing industry nowadays, biodiesel (methyl ester) has been identified as a sustainable fuel to replace petroleum. Hence, the separation and purification of the methyl ester after the trans-esterification process is essential since the purification of methyl ester is compulsory for the fuel industry in order to fulfill the strict global standard particulars for methyl ester. One of the current method used for separation and purification of methyl ester is called wet washing technology. However, this technology has its own drawbacks such as huge amount of water consumption as well as high cost for the wastewater treatment process. Due to these drawbacks, fractional crystallization process is proposed in order to save water and minimize the time consumed for the process of separation and purification of methyl ester. Fractional crystallization is a process that involved a solid-liquid separation where the process takes place in a crystallizer. In this process, methyl ester was separated from the glycerol based on their differences in term of melting point of the components. By observing the layer formation of the components, the effect of cooling time and coolant temperature on the performance of separation and purification of methyl ester by fractional crystallization process were studied. The purified methyl ester obtained was placed in a gas chromatographer in order to test the purity of methyl ester and to evaluate the efficiency of the process based on two parameters that has been investigated which are effective partition constant (K) and concentration efficiency (Eff). It was found that to achieve highest effectiveness of fractional crystallization system and highest concentration efficiency where K and Eff are 0.51 and 47.71%, respectively, the fractional crystallization must operate at coolant temperature range of -10 to -12ºC and cooling time range of 30 to 35 minutes.

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Spoerer, Yvonne, Regine Boldt, René Androsch, and Ines Kuehnert. "Pressure- and Temperature-Dependent Crystallization Kinetics of Isotactic Polypropylene under Process Relevant Conditions." Crystals 11, no. 9 (September 18, 2021): 1138. http://dx.doi.org/10.3390/cryst11091138.

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In this study, a non-nucleated homopolymer (HP) and random copolymer (RACO), as well as a nucleated HP and heterophasic copolymer (HECO) were investigated regarding their crystallization kinetics. Using pvT-measurements and fast scanning chip calorimetry (FSC), the crystallization behavior was analyzed as a function of pressure, cooling rate and temperature. It is shown that pressure and cooling rate have an opposite influence on the crystallization temperature of the materials. Furthermore, the addition of nucleating agents to the material has a significant effect on the maximum cooling rate at which the formation of α-crystals is still possible. The non-nucleated HP and RACO materials show significant differences that can be related to the sterically hindering effect of the comonomer units of RACO on crystallization, while the nucleated materials HP and HECO show similar crystallization kinetics despite their different structures. The pressure-dependent shift factor of the crystallization temperature is independent of the material. The results contribute to the description of the relationship between the crystallization kinetics of the material and the process parameters influencing the injection-molding induced morphology. This is required to realize process control in injection molding in order to produce pre-defined morphologies and to design material properties.

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Kang, Yue, Chao Liu, Yuzhu Zhang, and Hongwei Xing. "Influence of Crystallization Behavior of Gas Quenching Blast Furnace Slag on the Preparation of Amorphous Slag Beads." Crystals 10, no. 1 (January 10, 2020): 30. http://dx.doi.org/10.3390/cryst10010030.

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Slag beads with different crystal content could be obtained through the gas quenching blast furnace slag (BFS) process. In order to increase the additional value of the slag beads as much as possible, it was necessary to restrain the crystallization of the slag beads as much as possible. In this paper, the mineral types and crystallization temperatures of BFS with different basicities and cooling rates were studied by using Factsage thermodynamic software, XRD, and differential scanning calorimeter (DSC) experiments, which obtained the gas quenching temperature and the cooling rate needed to restrain crystallization behavior in the gas quenching process; The crystallization mechanism was studied by calculating crystallization activation energy (Ec) using the DSC experiment, at the same time, the thermodynamic results were verified. The proper basicity and cooling rate of BFS were found to be conducive to the preparation of amorphous slag beads. The results showed that the initial crystallization temperature decreased with decreasing the basicity and increasing the cooling rate, which could increase the amorphous content of slag beads in the gas quenching process. The crystallization activation energy (Ec) increased with decreasing basicity, which increased the crystallization barrier.

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Hu, Yeyuan, Yang Liao, Yanyan Zheng, Kosuke Ikeda, Ryoji Okabe, Ruifen Wu, Ryota Ozaki, Jun Xu, and Qingyan Xu. "Influence of Cooling Rate on Crystallization Behavior of Semi-Crystalline Polypropylene: Experiments and Mathematical Modeling." Polymers 14, no. 17 (September 2, 2022): 3646. http://dx.doi.org/10.3390/polym14173646.

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As crystallization behavior has a great effect on the injection molding process, the flash differential scanning calorimetry (FSC) method was employed to study the influence of cooling rate on the crystallization behavior of a semi-crystalline polypropylene (PP). As the experimental results show, crystallization temperatures (onset crystallization temperature and maximum crystallization temperature) and crystallinity decrease as the cooling rate increases. In addition, the corresponding mathematical models were established to describe the relationship between the crystallization temperatures/crystallinity and the cooling rate. A revised Tait equation was also carried out based on the mathematical models.

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Biglione, Jordan, Yves Bereaux, J. Y. Charmeau, Renaud G. Rinaldi, Jean Balcaen, and Sambor Chhay. "Injection Blow Moulding Single Stage Process – Approach of the Material Behaviour in Process Conditions and Numerical Simulation." Key Engineering Materials 651-653 (July 2015): 805–11. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.805.

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Single stage injection blow moulding process, without preform storage and reheat, could be run on a standard injection moulding machine, with the aim of producing short series of specific hollow parts. In this process, the preform is being blow moulded after a short cooling time. Polypropylene (Random copolymer) is a suitable material for this type of process. The preform has to remain sufficiently melted to be blown. This single stage process introduces temperature gradients, molecular orientation, high stretch rates and high cooling rates. These constraints lead to a small processing window, and in practice, the process takes place between the melting temperature and the crystallization temperature. To investigates the mechanical behaviour in conditions as close to the process as possible, we ran a series of experiments: First, Dynamical Mechanical Analysis was performed starting from the solid state at room temperature and ending in the vicinity of the melting temperature. Conversely, oscillatory rheometry was also performed starting this time from the molten state at 200°C and decreasing the temperature down to the vicinity of the crystallization temperature. The influence of the shear rate and of the cooling kinetics on the enhancement of the mechanical properties when starting from the melt is discussed. This enhancement is attributed to the crystallization of the material. The question of the crystallization occurring at such high stretch rates and high cooling rates is open. A viscous Cross model has been proved to be relevant to the problem. Thermal dependence is assumed by an Arrhenius law. The process is simulated through a finite element code (POLYFLOW software) in the Ansys Workbench framework. Thickness measurements using image analysis are performed and comparison with the simulation results is satisfactory.

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Władysiak, R., A. Kozuń, K. Dębowska, and T. Pacyniak. "Analysis of Crystallization Process of Intensive Cooled AlSi20CuNiCoMg Alloy." Archives of Foundry Engineering 17, no. 2 (June 27, 2017): 137–44. http://dx.doi.org/10.1515/afe-2017-0065.

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Abstract The work is a continuation of research concerning the influence of intensive cooling of permanent mold in order to increase the casting efficiency of aluminium alloys using the multipoint water mist cooling system. The paper presents results of investigation of crystallization process and microstructure of multicomponent synthetic hypereutectic alloy AlSi20CuNiCoMg. The study was conducted for unmodified silumin on the research station allowing the cooling of the special permanent sampler using a program of computer control. Furthermore, the study used a thermal imaging camera to analyze the solidification process of multicomponent alloy. The study demonstrated that the use of mold cooled with water mist stream allows in wide range to form the microstructure of hypereutectic multicomponent silumin. It leads to higher homogeneity of microstructure and refinement of crystallizing phases of casting.

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Liutyi, Rostyslav, Ivan Petryk, Volodymyr Mogylatenko, Vasyl Popovych, and Halyna Shatska. "Research Thermal Fields in the Crystallization Process of Steel Cast Parts." Advances in Materials Science and Engineering 2022 (December 5, 2022): 1–9. http://dx.doi.org/10.1155/2022/7331866.

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In foundry production, the duration of metal crystallization of the cast part, as well as the distribution of the thermal field, are described by systems of analytical equations. There are a number of methods for modeling these processes, but their theoretical basis was formed at the end of the twentieth century, and it needs to be updated and clarified. Therefore, the aim of our work is to develop a new analytical method for researching the distribution of thermal fields in cast parts during crystallization. For the first time, on the basis of own analytical and thermophysical developments, it developed the analytical method for researching the thermal field of the casting during crystallization and cooling, which is based on establishing the kinetics of cooling of the casting surface in the foundry mold, the advancement of the crystallization front from the surface to the center of the casting, and the distribution of temperatures in the solid and liquid parts of the casting. The method is expressed in a number of analytical formulas, each of which describes the specific thermal process that occurs in the casting. The developed analytical method was used to research the crystallization of the casting in a one-time sand mold, using the example of researching the thermal field of the cast part made of carbon steel with 0.25% C, hollow cylindrical shape, with the wall thickness of 100 mm. The developed analytical method for researching the thermal fields of cast parts is the analytical basis for the refinement of applied computer programs for modeling crystallization and cooling processes in foundry production.

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Li, Xiaopeng, Zeyu Zhang, Yi Yang, Jikang Fan, Jian Kong, and Kehong Wang. "The Crystallization Mechanism of Zr-Based Bulk Metallic Glass during Electron Beam Remelting." Materials 13, no. 16 (August 7, 2020): 3488. http://dx.doi.org/10.3390/ma13163488.

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Bulk metallic glasses (BMGs) are promising for multifunctional and structural application in different industries. However, the limited size of BMGs hinders their further application. The welding of BMGs has shown the possibility of getting rid of the casting size limitation. The heat-affected zone (HAZ) and fusion zone (FZ) often undergo severe crystallization during the welding process. It is still unclear whether the crystallization occurs during the heating process or the cooling process. To figure out the crystallization mechanisms of Zr-based BMGs during the electron beam welding process, the Zr-based BMGs with the composition of Zr41.2Ti13.8Cu12.5Ni10Be22.5 were remelted by electron beam. The microstructures of the HAZ and the remelting zone (RZ) were analyzed. The thermal field of the electron beam welding was obtained by the finite element method (FEM). The critical conditions for crystallization during the heating and cooling processes were obtained by differential scanning calorimetry (DSC) and the Kissinger equation. The results show that the Zr41.2Ti13.8Cu12.5Ni10Be22.5 in the HAZ undergoes severe crystallization, while the Zr41.2Ti13.8Cu12.5Ni10Be22.5 in RZ keeps amorphous state after the remelting process. The low cooling rate in the HAZ is responsible for its crystallization.

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Zhang, Caiduan, Feng Liu, Fengjia Wang, Haotian Li, Fang Zeng, Yongliang Ma, and Lidong Wang. "Crystallization process and nucleation kinetics of Mg2+//SO42−, NO3−-H2O system." Water Science and Technology 80, no. 5 (September 1, 2019): 950–60. http://dx.doi.org/10.2166/wst.2019.341.

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Abstract In order to achieve efficient recovery of ions from the simultaneous desulfurization and denitrification wastewater, the effects of various factors (i.e. the saturation temperature, the cooling termination temperature, the stirring rate and the cooling rate) on crystallization yield, metastable zone width and crystal morphology were investigated to determine the optimal crystallization conditions of Mg2+//SO42−, NO3–-H2O system. According to the results of experiments, the nucleation kinetics were also speculated by Nývlt self-consistent equation and classical 3D nucleation theory. Also, the crystallization products were characterized by X-ray diffraction and scanning electron microscopy. Under the determined optimal conditions, the yield of the crystal can reach 78%, and the crystal products were verified as pure MgSO4· 7H2O, whose morphology is complete without defects.

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Yang, Xu, Yusheng Wu, Laishi Li, Yuzheng Wang, and Mingchun Li. "Crystallization mechanism of ammonium aluminum sulfate during cooling process." Journal of Crystal Growth 560-561 (April 2021): 126064. http://dx.doi.org/10.1016/j.jcrysgro.2021.126064.

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Prlic Kardum, J., M. Hrkovac, and M. Leskovac. "Adjustment of Process Conditions in Seeded Batch Cooling Crystallization." Chemical Engineering & Technology 36, no. 8 (July 4, 2013): 1347–54. http://dx.doi.org/10.1002/ceat.201300221.

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Suljkanovic, Midhat, Milovan Jotanovic, Elvis Ahmetovic, and Nidret Ibric. "Multivariant simulator for vacuum cooling processes of three component electrolyte systems." Chemical Industry 64, no. 1 (2010): 21–33. http://dx.doi.org/10.2298/hemind1001021s.

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In this paper, a computer aided analysis and synthesis of the crystallization processes from multicomponent electrolyte systems were studied. In addition, the vacuum crystallization processes with adiabatic cooling of the system are presented. The cooling process of a multicomponent electrolyte system can be considered as a process with the concentration of the system and/or the crystallization of the solid phase from the system. Requirements for multivariant options of the process simulator are the result of practical needs in the design of new processes or the improvement of exploitation processes. According to this, there are needs for a simulation of a simple flashing of the system as well as for the vacuum cooling crystallization processes with the cyclic structure. The possibilities of the created process simulator are illustrated on three component electrolyte systems. Application of the process simulator for any other electrolyte systems requires only an update of the thermodynamic model, and physico-chemical properties related to electrolyte system.

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Suljkanovic, Midhat, Milovan Jotanovic, Elvis Ahmetovic, Goran Tadic, and Nidret Ibric. "Formalized methodology for the separation of three component electrolytic systems: Partial separation of the system." Chemical Industry 67, no. 4 (2013): 569–83. http://dx.doi.org/10.2298/hemind120808099s.

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This work presents a formalized methodology for salt's separation from three component electrolytic systems. The methodology is based on the multi-variant modelling block of a generalized crystallization process, with options for simulating the boundary conditions of feasible equilibrium processes and the elements of crystallization techniques. The following techniques are considered: cooling crystallization, adiabatic evaporative-cooling crystallization, salt-out crystallization, isothermal crystallization, and a combination of the mentioned techniques. The multi-variant options of the crystallization module are based on different variable sets with assigned values for solving mathematical models of generalized crystallization processes. The first level of the methodology begins with the determination of salt crystallization paths from a hypothetical electrolytic AX-BX-H2O system, following by an examination of salt-cooling crystallization possibilities. The second level determines feasible processes by the communication of a feed-system with the environment through a stream of evaporated water, or introduced water with introduced crystallized BX salt. The third level determines the value intervals of the variables for feasible processes. The methodological logic and possibilities for the created process simulator are demonstrated on examples of sodium sulphate separation from the NaCl-Na2SO4-H2O system, using different salt concentrations within the feed system.

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Huang, Yaohui, Ling Zhou, Wenchao Yang, Yang Li, Yongfan Yang, Zaixiang Zhang, Chang Wang, Xia Zhang, and Qiuxiang Yin. "Preparation of Theophylline-Benzoic Acid Cocrystal and On-Line Monitoring of Cocrystallization Process in Solution by Raman Spectroscopy." Crystals 9, no. 7 (June 27, 2019): 329. http://dx.doi.org/10.3390/cryst9070329.

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Pure theophylline-benzoic acid cocrystal was prepared via slurry and cooling crystallization in solution to overcome the disadvantages of existing preparation methods. The target cocrystal was characterized by powder X-ray diffraction (PXRD), thermalgravimetric analysis (TGA), differential scanning calorimetry (DSC) and Raman spectroscopy. The slurry and cooling cocrystallization process in solution was monitored via on-line Raman spectroscopy. The results obtained from on-line Raman monitoring can exhibit the transformation process from raw materials (theophylline and benzoic acid) to cocrystal and show the cocrystal formation rate. Comparing each transformation process under different conditions in slurry crystallization, we found that suspension density of raw materials and temperature both have an impact on the theophylline-benzoic acid cocrystal formation rate. It could be concluded that the cocrystal formation rate increased with the increase of suspension density of raw materials. Further under the same suspension density, higher temperature will accelerate theophylline-benzoic acid cocrystal formation. Meanwhile, various data from the cocrystallization process in cooling crystallization, including nucleation time, nucleation temperature and suitable cooling ending point can be gained from results of on-line Raman monitoring.

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Shiau, Lie-Ding. "Chiral Separation of the Phenylglycinol Enantiomers by Stripping Crystallization." Molecules 23, no. 11 (November 7, 2018): 2901. http://dx.doi.org/10.3390/molecules23112901.

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Stripping crystallization (SC) is introduced in this work for chiral purification of R-phenylglycinol from the enantiomer mixture with an initial concentration ranging from 0.90 to 0.97. As opposed to the solid–liquid transformation in melt crystallization, the three-phase transformation occurs in SC at low pressures during the cooling process. SC combines melt crystallization and vaporization to produce a crystalline product and mixture vapor from a mixture melt due to the three-phase transformation. Thermodynamic calculations were applied to determine the operating pressure for the three-phase transformation during the cooling process in the SC experiments. To consider the possible deviations between the calculated and the actual three-phase transformation conditions, the product purity and the recovery ratio of R-phenylglycinol were investigated within a range of operating pressures during the cooling process.

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Lv, Yunlong, and Chunlei Ruan. "Molecular dynamics simulation of nonisothermal crystallization of a single polyethylene chain and short polyethylene chains based on OPLS force field." e-Polymers 22, no. 1 (January 1, 2022): 136–46. http://dx.doi.org/10.1515/epoly-2022-0019.

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Abstract Molecular dynamics simulations on the nonisothermal crystallization of a single polyethylene chain and short polyethylene chains based on the all-atom model and optimized potentials for liquid simulations-all atom (OPLS-AA) force field are conducted in this article. Four all-atom single chain models with different chain lengths (C1000, C2000, C3000, and C4000) and four all-atom short chain models with the same chain length and different number of chains (2C500, 4C500, 6C500, and 8C500) are constructed. The collapse process at a high temperature of 600 K and the nonisothermal crystallization process with different cooling rates at the temperature range of 600–300 K are simulated. Roles of chain length, number of chains, cooling rate on the potential energy, van der Waals (V dw) energy, radius of gyration, root mean square deviation, and crystallinity are explored. By comparing with the existing results obtained by the united atom model, the validity and accuracy of this study are proved. Results show that in the collapse process, the chain length is the major factor, whereas the cooling rate has the greatest influence during the nonisothermal crystallization process. As the cooling rate decreases, a “platform” appeared in the V dw energy curve, which has a profound impact on the crystallization.

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Zhang, Ai Qun, and Yan Fei Wang. "A Novel Design of Heat Exchanger for Epsom Salt Cooling Crystallization." Advanced Materials Research 881-883 (January 2014): 1505–8. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1505.

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We introduced a design of a novel cooling heat exchanger for crystallization process of MgSO4.7H2O, and described the concepts of primary nucleation and secondary nucleation. To avoid the primary nucleation during crystallization process, the super-cooling degree limit of the salt lake brine was measured to define the supersaturation limit to MgSO4.7H2O, and the result is 1.32°C at-1°C. In this design, a primary circulation of solution is employed with a large enough flow rate to control the super-cooling degree of solution not to exceed 0.7 °C. A secondary circulation of cooling media is designed to add to this system, instead of the coldest cooling media being fed to shell directly, it is fed to the circulation pipe of the shell. It will help to prevent the supersaturation of solution exceeding the metastable zone width, thus to gurantee no primary nucleation during the Epsom salt crysatllization process.

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Wang, Liangyong, and Yaolong Zhu. "Neural-Network-Based Nonlinear Model PredictiveControl of Multiscale Crystallization Process." Processes 10, no. 11 (November 12, 2022): 2374. http://dx.doi.org/10.3390/pr10112374.

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The purpose of this study was to develop an integrated control strategyfor multiscale crystallization processes. An image analysis method using a deep learning neural network is used to measure the fine-scale information of the crystallization process, and the mathematical statistical method is adopted to obtain the mean size of the crystal population. A feedforward neural network is subsequently trained and employed in a nonlinear model predictive control formulation to obtain the optimal profile of the manipulated variable. The effectiveness of the proposed nonlinear model predictive control method is evaluated using alum cooling crystallization experiments. Experimental results demonstrate benefits of the proposed combination of feedforward neural network and nonlinear model predictive control method for the multiscale crystallization process.

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Huang, Hao, Yan-Hua Zhang, Li-Sha Zhao, Guang-Ming Luo, and Yan-Hua Cai. "Insight into the Role of a Isophthalic Dihydrazide Derivative Containing Piperonylic Acid in Poly(L-lactide) Nucleation: Thermal Performances and Mechanical Properties." Materiale Plastice 57, no. 3 (September 30, 2020): 28–40. http://dx.doi.org/10.37358/mp.20.3.5377.

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This work was aimed at synthesizing the N, N -isophthalic bis(piperonylic acid) dihydrazide (PAID) to be as a new crystallization accelerator for poly(L-lactide) (PLLA), and a detailed investigations of the non-isothermal crystallization, melting behavior, thermal decomposition behavior and mechanical properties of PLLA nucleated by PAID were performed applying differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and electronic tensile tester. The melt-crystallization proved that the PAID could act as a heterogeneous nucleating agent to significantly promote the crystallization in cooling, even the crystallization was still able to be accelerated upon the fast cooling at 50 oC/min. The final melt temperature was another crucial factor for PLLA�s melt crystallization, and when the final melt temperature was 170 oC, the onset crystallization temperature and melt-crystallization enthalpy was almost up to 150 oC and 56.8 J/g upon cooling of 1 oC/min, respectively. Furthermore, the chemical nucleation was proposed to be the nucleation mechanism of PAID for PLLA via the preliminary theoretical calculation. For the cold-crystallization, the addition of PAID exhibited an inhibition for the crystallization of PLLA, but the total crystallization process depended on the heating rate and PAID concentration. The single melting peak after cooling of 1 oC/min indicated that the crystallization had been thoroughly completed in cooling. Additionally, the single melting peak with different locations after full crystallization resulted from the different crystallization temperatures. A comparison in the onset decomposition temperature implied that the presence of PAID only slightly decreased the thermal stability of PLLA. The mechanical testing showed that, in contrast with the elongation at break, the existence of PAID enhanced the tensile strength of PLLA.

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Wang, Lei, and Min Su. "The Agglomeration of Niacin Crystals in the Cooling Crystallization Process." Crystal Research and Technology 56, no. 6 (March 22, 2021): 2000209. http://dx.doi.org/10.1002/crat.202000209.

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Ukrainczyk, Marko, B. Kieran Hodnett, and Åke C. Rasmuson. "Process Parameters in the Purification of Curcumin by Cooling Crystallization." Organic Process Research & Development 20, no. 9 (August 30, 2016): 1593–602. http://dx.doi.org/10.1021/acs.oprd.6b00153.

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Lindenberg, Christian, Martin Krättli, Jeroen Cornel, Marco Mazzotti, and Jörg Brozio. "Design and Optimization of a Combined Cooling/Antisolvent Crystallization Process." Crystal Growth & Design 9, no. 2 (February 4, 2009): 1124–36. http://dx.doi.org/10.1021/cg800934h.

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Kim, Do Yeon, Michaella Paul, Jens-Uwe Rapke, Günter Wozny, and Dae Ryook Yang. "Modelling of crystallization process and optimization of the cooling strategy." Korean Journal of Chemical Engineering 26, no. 5 (September 2009): 1220–25. http://dx.doi.org/10.1007/s11814-009-0207-6.

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Huang, Hao, Yanhua Cai, and Lisha Zhao. "Thermal properties and processability of modified poly(L-lactide): the role of phenylacetic acid hydrazide derivative." Polimery 67, no. 9 (September 20, 2022): 423–32. http://dx.doi.org/10.14314/polimery.2022.9.3.

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The influence of phenylacetic acid hydrazide (NAPAH) derivative content, melt temperature (170−200°C) and cooling rate (1−20°C/min) on poly (L-lactide) (PLLA) nucleation were investigated. Increasing the content of NAPAH (0.5−3.0 wt.%) had a positive effect on PLLA crystallization, while an increase in the cooling rate and heating temperature had a negative effect. In the case of isothermal crystallization carried out for a long time (180 min), the melting process depended only on the crystallization temperature. NAPAH also influenced the cold crystallization temperature, reduced thermal stability and improved PLLA processability (MFR).

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Kawakami, Kohsaku. "Crystallization Tendency of Pharmaceutical Glasses: Relevance to Compound Properties, Impact of Formulation Process, and Implications for Design of Amorphous Solid Dispersions." Pharmaceutics 11, no. 5 (May 1, 2019): 202. http://dx.doi.org/10.3390/pharmaceutics11050202.

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Amorphous solid dispersions (ASDs) are important formulation strategies for improving the dissolution process and oral bioavailability of poorly soluble drugs. Physical stability of a candidate drug must be clearly understood to design ASDs with superior properties. The crystallization tendency of small organics is frequently estimated by applying rapid cooling or a cooling/reheating cycle to their melt using differential scanning calorimetry. The crystallization tendency determined in this way does not directly correlate with the physical stability during isothermal storage, which is of great interest to pharmaceutical researchers. Nevertheless, it provides important insights into strategy for the formulation design and the crystallization mechanism of the drug molecules. The initiation time for isothermal crystallization can be explained using the ratio of the glass transition and storage temperatures (Tg/T). Although some formulation processes such as milling and compaction can enhance nucleation, the Tg/T ratio still works for roughly predicting the crystallization behavior. Thus, design of accelerated physical stability test may be possible for ASDs. The crystallization tendency during the formulation process and the supersaturation ability of ASDs may also be related to the crystallization tendency determined by thermal analysis. In this review, the assessment of the crystallization tendency of pharmaceutical glasses and its relevance to developmental studies of ASDs are discussed.

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Chen, Dejia, Lisha Lei, Meishuai Zou, and Xiaodong Li. "Non-Isothermal Crystallization Kinetics of Poly(Ethylene Glycol)–Poly(l-Lactide) Diblock Copolymer and Poly(Ethylene Glycol) Homopolymer via Fast-Scan Chip-Calorimeter." Polymers 13, no. 7 (April 4, 2021): 1156. http://dx.doi.org/10.3390/polym13071156.

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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.

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Jasiurkowska-Delaporte, Małgorzata, Tomasz Rozwadowski, and Ewa Juszyńska-Gałązka. "Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy." Crystals 9, no. 4 (April 12, 2019): 205. http://dx.doi.org/10.3390/cryst9040205.

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The kinetics of the non-isothermal and isothermal crystallization of the crystalline smectic B phase (soft crystal B, SmBcr) in 4-n-butyloxybenzylidene-4′-n′-octylaniline (BBOA) was studied by a combination of differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS) and polarized optical microscopy (POM). On cooling, part of the SmBcr phase undergoes conversion to a crystalline phase and the remainder forms a glassy state; after the glass softens, crystallization is completed during subsequent heating. By analyzing the area of the crystal growing in the texture of SmBcr as a function of time, the evolution of degree of crystallinity, D(t), was estimated. It was demonstrated that upon heating, D(t) follows the same Avrami curve as the crystallization during cooling. Non-isothermal crystallization observed during slow cooling rates (3K/min ≤ ϕ ≤ 5K/min) is a thermodynamically-controlled process with the energy barrier Ea ≈ 175 kJ/mol; however, the crystallization occurring during fast cooling (5 K/min > ϕ ≥ 30K/min) is driven by a diffusion mechanism, and is characterized by Ea ≈ 305 kJ/mol. The isothermal crystallization taking place in the temperature range 274 K and 281 K is determined by nucleus formation.

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Hu, Lei, Bin Yang, Ru Xia, Ji Bin Miao, Fei Xue Lu, Ming Cao, Jia Sheng Qian, and Yu Chuan Zhang. "Study on Solidification Kinetics and Crystallization Analysis of Dynamically-Vulcanized PP/EPDM Blends." Advanced Materials Research 1078 (December 2014): 8–11. http://dx.doi.org/10.4028/www.scientific.net/amr.1078.8.

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PP/EPDM blends were prepared by dynamic vulcanization technology within a HAAKE torque rheometer. The effect of different plastic/rubber ratios of PP/EPDM blends on the curing behavior and crystallization kinetics were investigated. The obtained results showed that the plastic/rubber ratios played an important part in the solidification process as well as the crystallization kinetics. With increasing EPDM content, the cooling rate of PP/EPDM blends was significantly larger than that of neat PP. When PP content was 20 wt%, the crystallinity of PP was obviously larger than that of neat PP. Compared with neat PP, the crystallization temperature of the blends were remarkably shifted to the lower temperature. EPDM particles showed active effect on the nucleation process of PP during the cooling crystallization of the PP/EPDM blends.

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Miao, Qingdong, Ming Li, Guanjin Gao, Wenbo Zhang, Jie Zhang, and Baijun Yan. "Improved Process for Separating TiO2 from an Oxalic-Acid Hydrothermal Leachate of Vanadium Slag." Metals 13, no. 1 (December 22, 2022): 20. http://dx.doi.org/10.3390/met13010020.

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In the present study, a process of separating high-quality TiO2 from an oxalic-acid leachate of vanadium slag was proposed. It consists of two steps; oxalic acid was firstly recovered from the leachate by the cooling-crystallization method, and subsequently TiO2 was separated from the oxalic-acid recovered leachate by the hydrothermal precipitation method. The experimental results indicate that oxalic acid can be recovered from the leachate by cooling crystallization at 5 °C, and after the recovery of oxalic acid, the purity of final TiO2 product can also be improved. For example, when the leachate was cooled directly at 5 °C for 5 h, about 7% of oxalic acid was recovered, and the purity of final TiO2 product improved from 95.7% to 96.6%. Furthermore, it was found that when some HCl solution was added to the leachate, both the recovery percentage of oxalic acid and the purity of TiO2 product increased. For instance, when 15 vol% of HCl solution relative to pregnant leachate was added, about 35% oxalic acid was recovered by cooling crystallization at 5 °C for 3 h, and the anatase TiO2 product with a purity of 99.2% was obtained by hydrothermal precipitation at 140 °C for 2.5 h.

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Fan, Helin, Dengfu Chen, Tao Liu, Huamei Duan, Yunwei Huang, Mujun Long, and Wenjie He. "Crystallization Behaviors of Anosovite and Silicate Crystals in High CaO and MgO Titanium Slag." Metals 8, no. 10 (September 24, 2018): 754. http://dx.doi.org/10.3390/met8100754.

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Electric-furnace smelting has become the dominant process for the production of the titanium slag from ilmenite in China. The crystallization behaviors of anosovite and silicate crystals in the high CaO and MgO titanium slag were studied to insure smooth operation of the smelting process and the efficient separation of titanium slag and metallic iron. The crystallization behaviors were studied by a mathematical model established in this work. Results show that the crystallization order of anosovite and silicate crystals in high CaO and MgO titanium slag during cooling is: Al2TiO5 > Ti3O5 > MgTi2O5 > MgSiO3 > CaSiO3 > FeTi2O5 > Mn2SiO4 > Fe2SiO4. Al2TiO5 and Ti3O5 have higher crystallization priority and should be responsible for the sharp increase in viscosity of titanium slag during cooling. The total crystallization rates of anosovite and silicate crystals are mainly controlled by Al2TiO5 and MgSiO3, respectively. The mass ratio of Ti2O3/ΣTiO2 has a prominent influence on the total crystallization rate of anosovite crystals while the mass ratio of MgO/FeO has a slight influence on the total crystallization rate of anosovite crystals.

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CAI, Yan-Hua, and Li-Sha ZHAO. "Heterogeneous Nucleation Effect of N, N'-Adipic Bis(4-phenylbutyric Acid) Dihydrazide on Crystallization Process of Poly(L-lactic Acid)." Materials Science 25, no. 4 (June 27, 2019): 446–54. http://dx.doi.org/10.5755/j01.ms.25.4.20603.

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Enhancing crystallization ability is a fundamental challenges in Poly(L-lactic acid) (PLLA) industry, therefore, the goal of this work was to synthesis a new organic nucleating agent N, N'-adipic bis(4-phenylbutyric acid) dihydrazide (APAD), and investigate its effect on non-isothermal crystallization, isothermal crystallization, melting behavior, thermal stability, and optical property of PLLA. Non-isothermal melt crystallization results showed that APAD acted as more effective nucleating and accelerating agent for the crystallization of PLLA, as a result, upon cooling at 1 °C/min, PLLA/0.5 %APAD had the highest onset crystallization temperature 136.4 °C and the crystallization peak temperature 132.0 °C, as well as the largest non-isothermal crystallization enthalpy 48.1 J/g. However, with increasing of APAD concentration from 0.5 wt.% to 3 wt.%, the crystallization peak shifted to the lower temperature. In contrast, for the non-isothermal cold crystallization process, the effect of APAD concentration on the crystallization behavior of PLLA was negligible. Additionally, the non-isothermal crystallization process was also depended on the cooling rates and the final melting temperature. In isothermal crystallization section, to compare with the primary PLLA, the crystallization half-time of PLLA/APAD could decrease from 254.3 s to the minimum value 29.4 s, with 0.5 wt.% APAD contents at 125 °C. Melting behavior of PLLA/APAD samples under different conditions further confirmed the heterogeneous nucleation effect of APAD for PLLA, and the appearance of the double melting peaks was attributed to the melting-recrystallization. Finally, the addition of APAD decreased the thermal stability to some extent, although APAD could not change the thermal decomposition profile of PLLA. And a drop of PLLA/APAD samples in light transmittance resulted from the double influence of the enhancement of crystallization and the opaqueness of APAD.

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Cai, Yan-Hua, and Li-Sha Zhao. "Study on Thermal Performance of Composites Prepared Using Poly(L-Lactic Acid) and Melamine." Open Materials Science Journal 10, no. 1 (April 30, 2016): 2–7. http://dx.doi.org/10.2174/1874088x01610010002.

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The goal of this work was to study the non isothermal and isothermal crystallization behavior of Poly(L-lactic acid) (PLLA) with melamine (TP) through differential scanning calorimeter and optical depolarizer. The study of the crystallization behavior of PLLA/TP composites indicated that TP could promote the crystallization of PLLA. The half time of overall crystallization of PLLA with 1.5 wt% TP, compared with the neat PLLA, gave rise to a decrease from 3999.44 s to the minimum value 228 s at 100 °C. In addition, the cooling rate also affected significantly the crystallization behavior of PLLA. The melting behavior of PLLA/TP composites exhibited a complicated and different melting process after cooling crystallization, and the increasing of TP content made melt mass flow rate of PLLA firstly decrease, then increases.

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Feng, Yaoguang, Hongxun Hao, Yiqing Chen, Na Wang, Ting Wang, and Xin Huang. "Enhancement of Crystallization Process of the Organic Pharmaceutical Molecules through High Pressure." Crystals 12, no. 3 (March 20, 2022): 432. http://dx.doi.org/10.3390/cryst12030432.

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The enhancement of the crystallization process through high pressures was studied by using ribavirin (RVB) as a model compound. The effects of high pressure on crystallization thermodynamics, nucleation kinetics, and process yield were evaluated and discussed. The solubility of ribavirin in three pure solvents was measured at different pressures from 283.15 to 323.15 K. The results indicate that the solubility data of ribavirin decreased slightly when pressure was increased. The induction time of the cooling crystallization of ribavirin under different pressures was measured. The results show that high pressure could significantly reduce the nucleation induction period. Furthermore, the nucleation kinetic parameters under different pressures were calculated according to the classical nucleation theory. The effect of high pressure on the anti-solvent crystallization of ribavirin was also studied.

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Höving, Stefan, Bastian Oldach, and Norbert Kockmann. "Cooling Crystallization with Complex Temperature Profiles on a Quasi-Continuous and Modular Plant." Processes 10, no. 6 (May 24, 2022): 1047. http://dx.doi.org/10.3390/pr10061047.

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Volatile markets and increasing demands for quality and fast availability of specialty chemical products have motivated the rise of small-scale, integrated, and modular continuous processing plants. As a significant unit operation used for product isolation and purification, cooling crystallization is part of this trend. Here, the small-scale and integrated quasi-continuous filter belt crystallizer (QCFBC) combines cooling crystallization, solid-liquid separation, and drying on a single apparatus. This contribution shows the general working principle, different operation modes, and possibilities of temperature control with the modular setup. For precise temperature control in cooling crystallization, Peltier elements show promising results in a systematic study of different operation parameters. Sucrose/water was used as a model substance system. The results confirm that seed crystal properties are the most important parameter in crystallization processes. Additionally, an oscillating temperature profile has a narrowing effect on the crystal size distribution (CSD). The integrated, small-scale, and modular setup of the QCFBC offers high degrees of flexibility, process control, and adaptability to cope with future market demands.

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Xie, Yi Huan. "Analysis of HDPE Crystallization for Axial Symmetric Cast." Applied Mechanics and Materials 268-270 (December 2012): 542–46. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.542.

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The paper studied the time depended crystallinity in a PE cast during the cooling process in mold. According to the competition theory between crystallization and its decomposition in HDPE polymer, a thermodynamic model and the differential equation for crystallization by cooling HDPE polymer was set up. A deference method was applied to solve the differential equation. The temperature and crystallinity were given in form of contour lines for an axial symmetric thick workpeace, and criterion based on the surface crystallization was proposed to determine the correct stripping time in a casting process. The model and the method are capable of calculating temperature and crystal concentration at any time and any mass point in a cast body, and are helpful for the choice of appropriate casting technology.

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Nawrocki, Jacek, Dariusz Szeliga, Krzysztof Kubiak, Hubert Matysiak, Maciej Motyka, and Waldemar Ziaja. "Influence of Process Parameters on Cooling Conditions in Nickel Base Superalloy Investment Casting." Key Engineering Materials 641 (April 2015): 124–31. http://dx.doi.org/10.4028/www.scientific.net/kem.641.124.

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The published results of the research on crystallization process of nickel base superalloy castings rarely take into account the effect of the wall thickness of the casting. Current study presents a comprehensive assessment of the impact of molten alloy temperature, mould temperature, mould thermal insulation and casting diameter on crystallization process of polycrystalline nickel base superalloy. Research was designed and conducted as an factorial experiment at two levels. Different diameter samples were designed and optimised by the numerical simulation of solidification process using ProCAST software. Inconel 713C nickel based superalloy was cast into alumina-silicate moulds produced by lost wax technique. Casting temperature during solidification was measured using thermocouples installed in sections having a diameter of 10 and 20 mm. Statistical analysis of the influence of the main process parameters and casting diameter on cooling rate, total freezing temperature range and critical temperature range was performed. Cooling rates in the range from 0.21 to 1.24°C/s were obtained. It was found that diameter of the casting, mould temperature and the thermal insulation of the mould had significant effect on the cooling rate.

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Lin, Ruohui, Meng W. Woo, Cordelia Selomulya, Jianping Lu, and Xiao Dong Chen. "Controlling the Size of Taurine Crystals in the Cooling Crystallization Process." Industrial & Engineering Chemistry Research 52, no. 37 (September 4, 2013): 13449–58. http://dx.doi.org/10.1021/ie4000807.

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Li, Yu, Xinyang Meng, Kuiyuan Chen, and Mansoor Barati. "Crystallization Behaviors of Spinel During Cooling Process of Modified EAF Slag." Metallurgical and Materials Transactions B 51, no. 3 (March 3, 2020): 1027–38. http://dx.doi.org/10.1007/s11663-020-01802-2.

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Maniara, Rafal, Leszek Adam Dobrzański, Jerry Sokolowski, Wojciech Kasprzak, and Witold T. Kierkus. "Influence of Cooling Rate on the Size of the Precipitates and Thermal Characteristic of Al-Si Cast Alloys." Advanced Materials Research 15-17 (February 2006): 59–64. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.59.

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In this work effect of cooling rate on the size of the grains, SDAS, β phases and thermal characteristic results of Al-Si cast alloys have been described. The solidification process was studied using the cooling and crystallization curve at cooling rate ranging from 0,1 °Cs-1 up to 1 °Cs-1. The main observation made from this work was that when cooling rate is increased the aluminum dendrites nucleation temperature and solid fraction at the dendrite coherency point increases, which implies that mass feeding is extended. In addition to that, it was observed that solidus temperature and size of the β phases decreases when cooling rate increases. Investigations were showed, that the thermal modification could be quantitatively assessed by analysis of the crystallization curve.

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Meng, Zong, Lijun Yang, Wenxin Geng, Yubo Yao, Xingguo Wang, and Yuanfa Liu. "Kinetic Study on the Isothermal and Nonisothermal Crystallization of Monoglyceride Organogels." Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/149753.

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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 that the crystal growth of MAG organogels was a rod-like growth of instantaneous nuclei at higher degrees of supercooling and a plate-like form with high nucleation rate at lower degrees of supercooling. The exothermic peak in nonisothermal DSC curves for the MAG organogels became wider and shifted to lower temperature when the cooling rate increased, and nonisothermal crystallization was analyzed by Mo equation. Results indicated that at the same crystallization time, to get a higher degree of relative crystallinity, a higher cooling rate was necessary. The activation energy of nonisothermal crystallization was calculated as 739.59 kJ/mol according to the Kissinger method. Therefore, as the results of the isothermal and nonisothermal crystallization kinetics for the MAG organogels obtained, the crystallization rate, crystal nucleation, and growth during the crystallization process could be preliminarily monitored through temperature and cooling rate regulation, which laid the foundation for the real industrial manufacture and application of the MAG organogels.

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Zhang, Jing, Lu Qi, and Zhen Yu Cui. "Nonisothermal Crystallization Behavior of Poly(vinylidenefluoride)/Polysulfone/Diethylene Glycol Dibenzoate/Dibutyl Phthalate System via Thermally Induced Phase Separation." Advanced Materials Research 1120-1121 (July 2015): 581–85. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.581.

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Differential scanning calorimetry (DSC) measurement is used to investigate the nonisothermal crystallization behavior of poly (vinylidene fluoride) (PVDF)/polysulfone (PSF)/diethylene glycol dibenzoate (DEDB)/dibutyl phthalate (DBP) system via solid-liquid (S-L) phase separation during a thermally induced phase separation process. The effect of benzene ring in PSF on PVDF crystallization for PVDF/PSF/DEDB/DBP system is investigated. It is found that the Ozawa model can describe nonisothermal crystallization behavior of PVDF/PSF/DEDB/DBP system in a certain crystallization temperature range. Jeziorny method indicates that the secondary crystallization of PVDF exists in the process of nonisothermal crystallization and is enhanced by the increase of cooling rate.

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Zhao, Li-Sha, Yan-Hua Cai, and Hui-Li Liu. "N, N’-sebacic bis(hydrocinnamic acid) dihydrazide: A crystallization accelerator for poly(L-lactic acid)." e-Polymers 19, no. 1 (May 29, 2019): 141–53. http://dx.doi.org/10.1515/epoly-2019-0016.

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AbstractDeveloping more organic nucleating agent with different molecular structure is very instructive to improve the crystallization of poly(L-lactic acid) (PLLA) and explore the crystallization mechanism. In this study, N, N’-sebacic bis(hydrocinnamic acid) dihydrazide (HAD) was synthesized to serve as a nucleating agent for PLLA. The effects of HAD on the non-isothermal crystallization, melting behavior, thermal stability and optical performance of PLLA were investigated by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and light transmittance meter. The melt crystallization behavior showed that HAD was able to promote the crystallization of PLLA via heterogenous nucleation in cooling, and it was found that, upon the cooling of 1°C/min, the incorporation of 1 wt% HAD made the crystallization temperature and non-isothermal crystallization enthalpy increase from 94.5°C and 0.1 J/g to 131.6°C and 48.5 J/g comparing with the pure PLLA. Additionally, the melt crystallization significantly depended on the cooling rate and the final melting temperature. For the cold crystallization, when the nucleation density from HAD and PLLA itself was saturated, the influence of the HAD concentration on the cold crystallization process of the PLLA/HAD samples is negligible. The melting behavior after isothermal or non-isothermal crystallization further confirmed the crystallization accelerating effect of HAD for PLLA, and the appearance of the double melting peaks was attributed to the melting-recrystallization. Unfortunately, the addition of HAD decreased the thermal stability and light transmittance of PLLA.

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Zhao, Li-Sha, and Yan-Hua Cai. "Insight on the effect of a piperonylic acid derivative on the crystallization process, melting behavior, thermal stability, optical and mechanical properties of poly(l-lactic acid)." e-Polymers 20, no. 1 (May 3, 2020): 203–13. http://dx.doi.org/10.1515/epoly-2020-0027.

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AbstractA new piperonylic acid derivative (BPASD) was synthesized and evaluated as an organic nucleating agent for poly(l-lactic acid) (PLLA) via melt-crystallization; the other behaviors including cold-crystallization, melting process after crystallization, thermal stability in air atmosphere, and optical and mechanical properties of PLLA/BPASD samples were also investigated. The results of the melt-crystallization investigation showed that, in comparison to virgin PLLA, the BPASD could induce PLLA to crystallize in higher temperature region or at a faster cooling rate, suggesting that the BPASD as a heterogeneous nucleating agent could promote the crystallization of PLLA, but the melt-crystallization depended on the cooling rate, BPASD concentration, and the final melting temperature. With increasing of BPASD concentration, a shift to the lower temperature of cold-crystallization peak and decrease of crystallization enthalpy indicated that BPASD had an inhibition for the cold-crystallization of PLLA to some extent. The heating rate, crystallization temperature, the BPASD, and its concentration were critical factors to the melting process, and double-melting peaks appeared in heating were assigned to melting–recrystallization. Thermal decomposition behavior revealed that the addition of BPASD reduced the thermal stability of PLLA, but the interaction of PLLA and BPASD could prevent the decrease of the onset decomposition temperature. Further, the BPASD also decreased the light transmittance and elongation at the break of PLLA, but the tensile modulus and tensile strength of PLLA were enhanced.

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Journal articles on the topic 'Cooling crystallization process'

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