crystallization process
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Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 224
Author(s):  
Siyu Pan ◽  
Zhiguo Jiang ◽  
Zhaobin Qiu

Poly(ethylene succinate-co-1,2-propylene succinate) (PEPS) is a novel aliphatic biodegradable polyester with good mechanical properties. Due to the presence of methyl as a side group, the crystallization rate of PEPS is remarkably slower than that of the poly(ethylene succinate) homopolymer. To promote the potential application of PEPS, the effect of cellulose nanocrystals (CNC) on the crystallization behavior, crystalline morphology, and crystal structure of PEPS was investigated in this research with the aim of increasing the crystallization rate. CNC enhanced both the melt crystallization behavior of PEPS during the cooling process and the overall crystallization rate during the isothermal crystallization process. The crystallization rate of PEPS became faster with an increase in CNC content. The crystalline morphology study directly confirmed the heterogeneous nucleating agent role of CNC. The crystal structure of PEPS remained unchanged in the composites. On the basis of the interfacial energy, the nucleation mechanism of PEPS in the composites was further discussed by taking into consideration the induction of CNC.


Author(s):  
N.K. Dosmukhamedov ◽  
◽  
E.E. Zholdasbay ◽  
V.A. Kaplan ◽  
G.S. Daruesh ◽  
...  

A laboratory setup has been developed to study the regularities of crystallization of aluminium chloride hexahydrate from hydrochloric acid solutions. The influence of the AlCl3 content in the initial solution, the consumption of gaseous HCl, and the behavior of impurities on the crystallization of AlCl3·6H2O from aluminium chloride solutions of leaching cinder obtained as a result of chlorinating ash burning from thermal power plants in Kazakhstan have been studied. The behavior of impurity metals in the process of crystallization of aluminium chloride solution has been studied, and their distribution between the products of the crystallization process has been established. It is shown that aluminium chloride content in the solution decreases with an increase in the consumption of hydrochloric acid. It was found that under the conditions of crystallization of AlCl3·6H2O, all impurities, except for barium, pass by 98% into the mother liquor. To reduce barium and other impurities in the obtained crystals of AlCl3·6H2O, it is proposed to carry out multiple washing of the crystals with hydrochloric acid (32% HCl). It has been shown that a decrease in the acidity of the washing solution from pH = 10 to pH = 5.5 ensures the isolation of ACH crystals with a minimum content of impurity metals, ppm: 3-5 Ca; 3-6 Fe; 1-3 Mg; 0.1-0.5 Ti; 1-3 Na; 20-30 P2O5. The moisture content of the obtained crystals is 4-5%; the particle size is 400-900 microns. As a result of mathematical processing, regression equations were constructed that adequately predict aluminium chloride content in the solution and its extraction into crystalline hydrate, depending on the consumption of hydrochloric acid. The optimal parameters of the crystallization process have been established: Т = 60 ºС, HCl concentration in the solution - 26-30%, HCl gas consumption = 0.5 l/min, duration 1 hour.


MOMENTO ◽  
2022 ◽  
pp. 66-82
Author(s):  
Edson A. S. Filho ◽  
Carlos B. B. Luna ◽  
Adriano L. Silva ◽  
Eduardo S. B. Ferreira ◽  
Edcleide M. Araújo ◽  
...  

The heat treatment effect on kaolin waste from mining was evaluated on the structural and thermal behavior of poly(ε-caprolactone) (PCL). The PCL/KW (kaolin waste) and PCL/HTKW (heat-treated kaolin waste) composites were processed in an internal mixer and subsequently characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The kaolin waste showed kaolinite and quartz in its composition, while the heat treatment at 1200°C modified it to mullite, quartz and silica-rich amorphous phase. By XRD, there was an increase in the intensity of the peak 2θ = 23.9° of the PCL/KW composites compared to neat PCL. In contrast, PCL/HTKW composites tended to reduce the intensity of the peak 2θ = 23.9°, especially at 5% HTKW. The crystalline melting temperature and the degree of crystallinity of PCL/KW and PCL/HTKW composites were practically unchanged, compared to PCL. However, the crystallization process was more effective with the kaolin waste (KW) without heat treatment, indicating that the HTKW amorphous phase inhibited crystallization. The PCL/KW development promoted an increase in crystallization temperature, relative crystallinity, and crystallization rate, surpassing PCL and the PCL/HTKW system. In view of this, kaolin waste has the potential to accelerate the PCL crystallization process, contributing to add value to a material that would otherwise be discarded and minimizing environmental impacts.


2022 ◽  
Vol 58 (4) ◽  
pp. 73-83
Author(s):  
Hao Huang ◽  
Shuang-Qing Liu ◽  
Cheng-Pei Li ◽  
Shi-Tianle Luo ◽  
Li-Sha Zhao ◽  
...  

In this study, a new organic nucleating agent N, N -bis(stearic acid)-1,4-dicarboxybenzene dihydrazide (PASH) to improve crystallization behavior of poly(L-lactic acid) (PLLA) along with the effect of PASH on melting behavior, thermal stability of PASH-nucleated PLLA was holistically reported. The melt-crystallization process illustrated that PASH as an effective heterogeneous nucleating agent could boost PLLA�s crystallization rate, but increasing PASH concentration and cooling rate conversely inhibited melt-crystallization process of PLLA in this study. With respect to melt-crystallization process, a larger amount of PASH leaded to a shift of cold-crystallization peak to lower temperature level. Isothermal crystallization revealed, in comparison to pure PLLA, that the half time of overall crystallization of PLLA/PASH was significantly decreased with PLLA containing 3 wt% PASH having the minimum t1/2= 67.3 s at 105şC. The different melting behaviors of PLLA/PASH under different conditions were attributed to the nucleating effect of PASH within PLLA. In particular, the melting behavior at a heating rate of 10�C/min after isothermal crystallization depended primarily on the crystallization temperature. Whereas, the impact of crystallization time on melting behavior was negligible. Nonetheless, the melting behavior was influenced by the heating rate after non-isothermal crystallization. The thermal stability of PLLA was detrimental with the addition of PASH owing to a typical drop in onset thermal decomposition temperature.


Author(s):  
A. M. Mansour ◽  
bahaa Hemdan ◽  
Ali B Abou Hammad ◽  
hisham saleh ◽  
amany M elnahrawy

Abstract The structural and optical properties of 30 ZnO: 50 SiO2: (20-x) CuO (ZSC) loaded with E102 (tartrazine dye) (where x=0.02, 0.05, 0.07 wt.%) nanoclusters have been explored. These nanoclusters were synthesized by a sol-gel route followed by a very controlled crystallization process at 500oC. The phase formation, structural modification, and particle distribution behavior of these nanoclusters have been studied using XRD and TEM analysis to monitor the domestic environment for ZCS-E102. The optical transmission and reflection properties of nanoclusters in the UV-Vis-NIR range were studied for the present nanoclusters from which the optical absorption was calculated. Tauc method is employed to estimate the type and value of energy needed to gap transition from absorption data. The direct and indirect gap shows decreased energy need for its transition by E102 concentration increase. The antimicrobial potentials of four synthesized nanoclusters were performed against some pathogenic microbes. The toxicity performance of all studied nanoclusters is measured. Results revealed that ZSC-0.07E102 is showed an effective antimicrobial action against four tested pathogenic microbes in terms of excellent inhibitory effect and biocompatibility show noticeable potential in the antimicrobial application. Therefore, this proficient nanomaterial is a promising choice for biomedical purposes.


2022 ◽  
Author(s):  
Zihan Lin ◽  
Xiubo Xie ◽  
Dan Wu ◽  
Xiangyang Feng ◽  
Mengna Chen ◽  
...  

Celery biomass carbon supercapacitor electrodes with tunable Co3O4 loading are designed through oxidation-precipitation and crystallization process of Co ions. The Co3O4 particles uniformly decorated on the surface of the sheet-like...


Desalination ◽  
2022 ◽  
Vol 521 ◽  
pp. 115389
Author(s):  
Guozhao Ji ◽  
Weijian Wang ◽  
Huihuang Chen ◽  
Siyuan Yang ◽  
Jing Sun ◽  
...  

2022 ◽  
Vol 92 (1) ◽  
pp. 58
Author(s):  
Б.А. Русанов ◽  
В.Е. Сидоров ◽  
P. Svec ◽  
D. Janickovic ◽  
В.И. Ладьянов ◽  
...  

In present work amorphous alloys Co48Fe25Si4B19Nb4-R (R = Nd, Sm, Tb, Yb) were obtained by planar flow casting in the form of ribbons with 3-5 mm wide and 35-45 μm thickness. It was found that crystallization process goes into two stages and depends on the used rare-earth addition and its content in the alloy by differential thermal analysis method. Glass-forming ability criteria were calculated. It is shown that paramagnetic Curie temperature of alloys in liquid state can be used as their a-priori criterion of glass-forming ability.


Author(s):  
Chang Bao Han ◽  
Man Qi Wang ◽  
Xiaobo Zhang ◽  
Shaoxin Yan ◽  
NABONSWENDE AIDA NADEGE OUEDRAOGO ◽  
...  

Perovskite solar cells (PSCs) have received tremendous attention because of their advantages of low fabrication cost and rising power conversion efficiency (PCE). However, the poor crystalline quality of perovskite materials...


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