Increasing Crystallization Temperature Research Articles

Correlation of thermal and electrical properties of silver germanophosphate glasses with their structural analysis by Raman and NMR spectroscopy

In present study glasses of the system Ag2O-GeO2-P2O5 were studied in the compositional series (50−x)Ag2O-xGeO2-50P2O5 with x = 0−40 mol%. Ag2O substitution by GeO2 results in a significant increase of both glass transition temperature, Tg, and crystallization temperature, Tc, up to 628 °C (Tg) and 851 °C (Tc) at x = 40 mol% GeO2. The glass structure was investigated from the analysis of 31P MAS NMR and Raman spectra. Both methods show transformation of phosphate glass network formed mainly by Q2 units to germanate-phosphate network formed by Q1xGe and Q21Ge phosphate units and germanate units. Raman spectra, in addition, reveal evolution of P‒O‒P linkages to P‒O‒Ge and Ge‒O‒Ge linkages through the glass series. DC conductivity trend upon GeO2 addition showed non-monotonic behaviour, which is related to structural changes in the glass-network.

Effect of surfactin on the properties of glycerol monosterate – Based oleogels

This study aimed to prepare soybean oil oleogels with glycerol monostearate (GMS) and native surfactin organogelators. The effects of surfactin addition on the properties and microstructure GMS oleogel properties were evaluated. Gelation time, rheological and thermal properties, microscopy, Fourier transform infrared spectra, X-ray diffraction patterns, and oil binding capacity were determined. Results showed that addition of surfactin shortened the gelation time, enhanced hardness, oil binding capacity, apparent viscosity and gel strength, reduced crystals size and melting temperatures, increased crystallization temperature. GMS-surfactin oleogels showed larger mechanical resistance on compression. Hydrogen bonds were the main force for the formation of three-dimension oleogel network. Surfactin addition changed the crystal structure and β and β′ coexisted in oleogels. Oleogels with more stable texture and desirable properties were formed due to the addition of surfactin. Results indicated that surfactin addition could adjust the properties and micro-structure of GMS oleogels.

Energy-storage performance of NaNbO3-based ceramic capacitor derived from a high DOP glass network structure

0.75(0.4Na2O-0.1K2O-0.5Nb2O5)-0.25(0.87SiO2-0.13BaO) glass-ceramics were prepared by a traditional melting method to optimize the crystallization kinetics. We obtained a glass network with high degree of polymerization (DOP) by crystallization at different temperatures and achieved a high energy storage density. The increase of crystallization temperature has promoted the precipitation of ferroelectric phases Na0.9K0.1NbO3 and NaNbO3 with high dielectric constant (1200–2000), promoted the increases of grain size from 0.76 μm to 1.33 μm, and reduced the gap width from 3.71eV to 3.22eV. When the crystallization temperature increased to 1000°C–1100 °C, Ba2NaNb5O15 with low dielectric constant (∼460) increases, grain boundaries appear, and dielectric constant and BDS decrease. Among all the samples, the sample crystallized at 900 °C showed homogeneous and dense microstructure (grain size∼0.91 μm). The experimental data confirmed that the glass sample crystallized at 900 °C achieves low dielectric loss (<0.005) and high dielectric constant (∼122). The glass sample crystallized at 900 °C sample had a maximum energy storage density of 3.65 J/cm3, a power density of about 54 MW/cm3 and a super-fast discharge speed of 38 ns at 660 kV/cm.

Enhancing mechanical and shape memory properties of polylactide/polyamide elastomer blends via reactive blending with a chain extender

AbstractThe structure and properties of incompatible polylactide (PLA)/polyamide elastomer (PAE) blends were tailored by a chain extender specifically the styrene–glycidyl acrylate copolymer Joncryl ADR4368 (ADR). Various PLA/PAE/ADR blends with different compositions were prepared by melt blending, and their morphology, crystallization behavior, and mechanical and the shape memory properties were systematically investigated. The results showed a uniform dispersion of PAE particles in the PLA matrix for the PLA blends with a reduction in particle size upon the addition of ADR. The crystallization of PLA was retarded, which was confirmed by a decrease in the melt crystallization temperature and an increase in cold crystallization temperature in the PLA/PAE/ADR blends. Rheological analysis showed an improvement in the melt elasticity of the PLA/PAE binary blend due to the presence of ADR, possibly attributed to the formation of long‐chain‐branched copolymers at the interface. Notably, the PLA/PAE/ADR blend exhibited superior toughness, featuring an elongation at break of 288% and a notched impact strength of 37 kJ·m−2, along with a high shape memory fixation rate and recovery rate when the ADR content was 1 wt%. Furthermore, the underlying toughening mechanism was elucidated. This work may offer an industrially scalable relevant model to fabricate high‐performance PLA materials.

Fluorescent contactless method for temperature determination of YAl3(BO3)4 crystals doped with Yb3+ ions

Here we present an experimental implementation of the fluorescence concatless method for the temperature determination of YAl3(BO3)4 crystals doped with Yb3+ ions. We have investigated the anti-Stokes fluorescence spectra of the crystal in the 900-1020 nm spectral range. The spectra have been measured while heating the crystal in the temperature range from 290 to 573 K. The increase of crystal temperature results in an enhancement of the relative fluorescence intensity in the short-wavelength region. The linear dependencies obtained can be used as a calibration function for contactless temperature measurements of YAl3(BO3)4 laser crystals doped with Yb3+ ions.

Advancing controlled-release phosphate glasses as sustainable fertilizers: Microelement-enhanced formulations and dissolution behavior analysis

In this study, we explore the potential of phosphate glasses as controlled-release fertilizers, addressing the need for sustainable nutrient management in agriculture. Our approach involves the systematic incorporation of microelements (Fe, Mn, Zn, B, Cu, Mo) into phosphate glasses to assess their impact on the glass's physicochemical properties. For this, seven phosphate glasses were synthesized using a combination of raw materials, and a series of experiments to analyze their thermal properties, structural characteristics, and dissolution behaviors were conducted. Results from the thermal analysis revealed an increase in glass transition, crystallization, and melting temperatures with progressively incorporating microelements indicating an enhancement in thermal stability. Structural characterizations unveiled a prevalent presence of Q2 units in the phosphate network, with discernible Q1 units existing as shorter phosphate chains within the matrix. The inclusion of microelements enhances the chemical durability of the glasses, with specific elements like iron and manganese significantly reducing dissolution rates. This enhanced chemical stability aligns with the requirements for controlled-release fertilizers as defined by ISO 18,644 standards. This study offers valuable insights into the interactions of microelements within phosphate glass matrices, highlighting their potential as effective and environmentally friendly controlled-release fertilizers. By meeting the ISO 18,644 criteria for controlled-release fertilizers, these glasses hold promise for sustainable agriculture practices.

Accelerated nonisothermal crystallization and improved material properties of biobased poly(butylene 2,5-furandicarboxylate)/talc composites

Biobased poly(butylene 2,5-furandicarboxylate) (PBF) reflects the much poorer crystallizability than its petroleum-based counterpart poly(butylene terephthalate). By introducing talc platelets into PBF matrix to fabricate composites, the effects of low loadings’ layered filler upon nonisothermal melt crystallization and material properties of PBF/talc composites are investigated for the first time. Obviously accelerated crystallization of the composites relative to pure PBF is first evidenced by the simultaneous increase of crystallization temperature and decline of crystallization half-time, and further supported by both the crystallization rate coefficient and crystallization rate parameter. Nonisothermal crystallization kinetics are analyzed by both the Jeziorny model and Mo equations, and the intensifying effect of talc upon PBF's crystallization is attributed to the coupling of enlarging nucleation activity and lowering crystallization activation energy. Meanwhile, the incorporation of layered talc doesn't modify the crystal structure of PBF. Moreover, both the thermal and mechanical properties of PBF/talc composites are reinforced slightly.

The role of arsenic in the operation of sulfur-based electrical threshold switches

Arsenic is an essential dopant in conventional silicon-based semiconductors and emerging phase-change memory (PCM), yet the detailed functional mechanism is still lacking in the latter. Here, we fabricate chalcogenide-based ovonic threshold switching (OTS) selectors, which are key units for suppressing sneak currents in 3D PCM arrays, with various As concentrations. We discovered that incorporation of As into GeS brings >100 °C increase in crystallization temperature, remarkably improving the switching repeatability and prolonging the device lifetime. These benefits arise from strengthened As-S bonds and sluggish atomic migration after As incorporation, which reduces the leakage current by more than an order of magnitude and significantly suppresses the operational voltage drift, ultimately enabling a back-end-of-line-compatible OTS selector with >12 MA/cm2 on-current, ~10 ns speed, and a lifetime approaching 1010 cycles after 450 °C annealing. These findings allow the precise performance control of GeSAs-based OTS materials for high-density 3D PCM applications.

Isothermal crystallization behavior of poly-ether-ether-ketone/bioactive glass composites and its correlation with scaffold warpage in laser powder bed fusion process

The preparation of poly-ether-ether-ketone/bioactive glass (PEEK/BG) composite scaffolds using laser powder bed fusion (LPBF) has enormous clinical potential. However, ensuring the desired accuracy and reproducibility of composite scaffolds during the LPBF process remains a significant challenge. Therefore, a thorough understanding of the relationship between the crystallization behaviors and the scaffold warpage during the LPBF process is crucial. To address this challenge, this study systematically investigates the isothermal crystallization kinetics of PEEK/BG composites and their relationship with scaffold warpage. The results reveal that the crystallization rates of pure PEEK and PEEK/BG composites decrease as isothermal crystallization temperature increases. Additionally, BG significantly suppresses the isothermal crystallization kinetics of PEEK, resulting in a 250% increase in the half-crystallization time (t1/2) of PEEK/25 wt% BG at 316 °C relative to pure PEEK. Extrapolating the t1/2 using the Hoffman-Lauritzen model can obtain the optimal powder bed temperature (Tb) for each powder in LPBF. Pure PEEK and PEEK/25 wt% BG Diamond scaffolds are printed at the respective inferred Tb (330 °C and 323 °C) and their warpage degrees are compared to that of the pure PEEK scaffold printed at 323 °C. The results demonstrate that raising Tb from 323 °C to 330 °C and adding 25 wt% BG are both effective methods to reduce the scaffold warpage by slowing down the crystallization kinetics of PEEK, resulting in reductions of 57.8% and 50.6% in warpage degree respectively. Furthermore, the incorporation of BG successfully tackles the challenge of simultaneously preventing warpage and secondary sintering in pure PEEK printing. Overall, this study offers a deep comprehension regarding the relationship between crystallization kinetics and scaffold warpage, which is crucial for achieving the reproducibility with desired accuracy of LPBF-printed biological scaffolds for clinical applications.

Suitability of MRF Recovered Post-Consumer Polypropylene Applications in Extrusion Blow Molded Bottle Food Packaging.

Polypropylene (PP) is one of the most abundant plastics used due to its low price, moldability, temperature and chemical resistance, and outstanding mechanical properties. Consequently, waste from plastic materials is anticipated to rapidly increase with continually increasing demand. When addressing the global problem of solid waste generation, post-consumer recycled materials are encouraged for use in new consumer and industrial products. As a result, the demand is projected to grow in the next several years. In this study, material recovery facility (MRF)-recovered post-consumer PP was utilized to determine its suitability for extrusion blow molded bottle food packaging. PP was sorted and removed from mixed-polymer MRF-recovered bales, ground, trommel-washed, then washed following the Association of Plastics Recyclers' protocols. The washed PCR-PP flake was pelletized then manually blended with virgin PP resin at 25%, 50%, 75, and 100% PCR-PP concentrations and fed into the extrusion blow molding (EBM) machine. The EBM bottles were then tested for physical performance and regulatory compliance (limits of TPCH: 100 μg/g). The results showed an increased crystallization temperature but no practical difference in crystallinity as a function of PCR-PP concentrations. Barrier properties (oxygen and water vapor) remained relatively constant except for 100% MRF-recovered PCR-PP, which was higher for both gas types. Stiffness significantly improved in bottles with PCR-PP (p-value < 0.05). In addition, a wider range of N/IAS was detected in PCR-PP due to plastic additives, food additives, and degradation byproducts. Lastly, targeted phthalates did not exceed the limits of TPCH, and trace levels of BPA were detected in the MRF PCR-PP. Furthermore, the study's results provide critical information on the use of MRF recovered in food packaging applications without compromising performance integrity.

Mechanical properties and thermal stability of ZrCuAlx thin film metallic glasses: Experiments and first-principle calculations

In this work, we provide a holistic picture about the relationship between atomic structure, mechanical properties, and thermal stability of ZrCuAlx thin film metallic glasses (TFMGs) varying the Al content from 0 to 12 at.%, carrying out a broad characterization involving experiments and ab initio molecular dynamic simulations (AIMD). We show that the addition of Al resulted in a change of average interatomic distances by ∼10 pm with the formation of shorter bonds (Al-Zr and Al-Cu), influencing the mechanical response (shear/elastic moduli and hardness) which increases by ∼15% for 12 at.% Al. Moreover, tensile tests on polymer substrate revealed a maximum value for the crack initiation strain of 2.1% for ZrCuAl9, while the strain-to-failure rapidly decreases at higher Al contents. The observed reduction in damage tolerance is correlated to a transition in atomic configuration. Specifically, a maximum in density of full and defective icosahedral cluster population is observed at 9 at.% Al, inducing a more shear-resistant behavior to the material. Thermal stability is investigated by high-energy and conventional x-ray diffraction and electrical resistivity measurements as a function of the temperature. Glass transition (Tg) and crystallization (Tx) temperature increase by Al addition reaching 450 and 500 °C, respectively for ZrCuAl12. The increase in thermal stability is related to the reduction in atomic mobility due to the formation of shorter chemical bonds, inhibiting atomic reconfiguration during crystallization. In conclusion, we provide guidelines to the design of compositional-tailored ZrCuAlx TFMGs with tuned mechanical properties and thermal stability with potential impact on industrial applications.

Surface-enhanced nucleation in immiscible polypropylene and polyethylene blends: The effect of polyethylene chain regularity

In blends where polyethylene (PE) is the minor component dispersed in an isotactic-polypropylene (PP) matrix, an enhancement of the crystallization rate of PE was found when the crystallization temperature of the matrix phase is increased by means of a self-nucleation protocol. Such an effect is interpreted as the result of the epitaxial nucleation of PE droplet domains at the interface with the PP matrix (Macromolecules, 2021, 54, 19, 9100–9112). This study extends the findings on immiscible blends of a PP matrix and various industrially produced PE grades as the dispersed phase. Eight different PEs with varying molecular architecture, and thus density and melting temperatures, were mixed with PP in a 20/80 PE/PP weight ratio. The possible existence of surface nucleation was probed by applying a self-nucleation thermal protocol to the PP matrix and recording the concomitant variation of PE crystallization temperature (Tc). Different behaviours are observed for various PEs. In particular, those with relatively high density display a clear increase in crystallization temperature, over 3.0 °C, when the Tc of the matrix is increased (i.e., as PP lamellar thickness increased), indicating an efficient surface nucleation mechanism. Metallocene-made LLDPE also shows a small increase, about 1.7 °C, while PEs with lower densities, below 927 kg/m3, metallocene PEs or LDPE display no meaningful change in Tc with matrix self-nucleation. It was demonstrated that a threshold value of chain regularity is required to trigger the surface nucleation of PE on PP. Only polymers with a density above approximately 920 kg/m3 and melting temperatures exceeding about 115 °C can efficiently nucleate onto the PP substrate. It is postulated that the presence of a high amount of branches or comonomers along the PE chains hinders the epitaxial matching between PE and PP.

Effect of CH2 run length on the crystallization kinetics of sustainable long-spaced aliphatic polyesters

We have studied the isothermal overall crystallization rates and linear growth rates of four symmetric long-spaced aliphatic polyesters (LSAPEs) with 12, 18, 32, or 48 carbons in both the diol and the diacid monomers. With increasing crystallization temperature (Tc) these LSAPEs display discrete rate minima in a number and depth that depend on the length of the methylene spacer between esters. Two rate minima are observed for PE-48,48 and for PE-32,32; one for PE-18,18 and none for PE-12,12. The rate minima are not associated with a change in the mechanism of nucleation and growth or with a change in crystal packing, but occur at Tc where the crystal thickness transitions from a non-integer to a quantized integer number of monomer units. We explain such rate minima based on the self-poisoning feature used earlier to explain similar findings in n-alkanes and other types of precision polyethylene-like systems. In LSAPEs, metastable non-integer crystals attach to the growth front of stable integer crystals retarding their growth until the non-integer segments thicken to complete the layer. Lack of rate minima in the shortest-spaced symmetric polyester is explained by a small difference in lamellar thickness between non-integer and integer layered crystals which favors the formation of integer crystals at any Tc.

Preparation of nanometer zirconia by hydrothermal method: Influence of temperature and mechanism

Monoclinic (m-ZrO2) and tetragonal zirconia (t-ZrO2) nanoparticles with average grain size of 22.8 nm were synthesized by hydrothermal method using zirconium oxychloride octahydrate (ZrOCl2·8H2O), urea (CO(NH2)2) and deionized water as zirconium source, precipitant, and solvent, respectively. The effects of CO(NH2)2 hydrolysis rate, hydrothermal temperature, and time on the crystal structure, morphology, and grain size were studied. The structure, morphology, grain size, and crystal phase of zirconium oxide (ZrO2) were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetry (TG-DTA), and Fourier Transform Infrared spectroscopy (FT-IR). The results show that the formation mechanisms of different crystal forms can be controlled by the average pH value. The hydrolysis rate of CO(NH2)2 was relatively slow at 120 °C, resulting in a slower rate of OH− production. The lower average pH value favors the formation of m-ZrO2 through the dissolution precipitation mechanism. With the increase of crystallization temperature, the hydrolysis rate of CO(NH2)2 is accelerated, and the average pH value of the solution is increased, which is conducive to the structural rearrangement of [Zr(OH)8(H2O)16]8+ precursor to form tetragonal phase. In addition, the number of defect sites is directly proportional to the crystallization temperature. Extension of crystallization time helps the generation of ZrO2 crystals by polycondensation and directional growth.

Optical and morphological properties of Ge-incorporated polycrystalline Sb2Se3 thin-film for photovoltaic applications

Crystalline Ge-incorporated Sb2Se3 thin-films are the promising absorber material for third-generation solar cells due to its optical, electrical, and material properties with earth-abundant materials. In this contribution, we have grown polycrystalline Ge-incorporated Sb2Se3 thin-film absorbers and conducted morphological and optical analysis by Scanning Electron Microscopy and UV–Vis spectroscopy along with the chemical structure analysis with Raman Spectroscopy for photovoltaic absorber applications. Ge-incorporated Sb2Se3 thin-films were deposited with Vapor Transport Deposition techniques, using thermally evaporated Sb2Se3 and Ge from each Sb2Se3 and Ge nanopowder source as precursors. Evaporation temperatures of Sb2Se3 and Ge nanopowder sources were independently controlled in the different heating zones of the furnace. At the deposition temperature of 300 °C, grains of Ge-incorporated Sb2Se3 thin-film begin to grow due to the increased crystallization temperature by Ge incorporation. With temperature-dependent absorption spectrum and the indirect optical transition natures, the optical bandgap of Ge-incorporated Sb2Se3 absorbers is extracted as 1.15 eV and 1.23 eV for samples grown at 500 °C and 520 °C.

Synthesis, microstructure and electromagnetic properties of Hf-based SiBCN ceramics

In this work, two kinds of ceramic polymers, polyborosilazane and polyhafnoxane, were mixed by a precursor blending method, followed by curing and pyrolysis to obtain Hf-based SiBCN ceramics. Through FTIR and NMR characterization of cured product, it can be found that the two precursors underwent cross-linking reaction during the curing process, resulting in the increase of crystallization temperature of HfO2 and β-SiC, and the formation of new components (HfB2 and HfN) during pyrolysis. When the pyrolysis temperature increases, the average values of the real part and imaginary part of the dielectric constant of Hf-based SiBCN ceramics increased from 7.2 to 4.9 to 9.0 and 6.6, respectively, resulting from the precipitation of HfB2 and HfC(N) with high dielectric constants. The effective absorption width decreased from 3.4 to 2.5 GHz, and the minimum value of reflection coefficient increased from −14.9 to −12.2 dB, which is caused by poor impedance matching. After being oxidized at 500 °C for 50 h in air, the free carbon basically disappears, and the full X-band absorption can be realized for the Hf-based SiBCN ceramic pyrolyzed at 1500 °C with a thickness of 2.8 mm.

Crystallization Behavior and Properties of Propylene/4-Methyl-1-pentene Copolymers from a Metallocene Catalyst

Copolymers of isotactic polypropylene (iPP) with 4-methyl-1-pentene (iPP4MP) were prepared with a highly isoselective homogeneous organometallic catalyst in a range of 4-methyl-1-pentene (4MP) concentrations between about 1.7 and 14 mol %. Crystallization from the melt at different crystallizations temperatures have been performed to study the effect of 4MP comonomeric units excluded from the crystals on the crystallization of α and γ forms. All samples crystallize in mixtures of α and γ forms, and for each sample, the fraction of γ form increases with increasing crystallization temperature to achieve a maximum value fγ(max), which depends on the 4MP concentration. Compared to the homopolymer, the maximum fractional amount of γ form fγ(max) rapidly increases with increasing 4MP content achieving the highest value of 92% at low 4MP concentration of 2.2 mol %, and decreases with a further increase of 4MP concentration. These data are compared with analogous data of the maximum amount of γ form that develops in copolymers of iPP with ethylene and butene. This allows comparing the different effects of rejection of defects from the crystals, which produces interruption of the regular propene sequences and shortening of the length of the crystallizable sequences, the inclusion of defects into crystals of α and γ forms, and the effect of the crystallization kinetics. Since 4MP comonomeric units are excluded from the crystals, the behavior of iPP4MP copolymers provides the sole interruption effect, which is highly efficient and produces the highest amount of γ form of 92% at low 4MP concentration of nearly 2 mol %. The observed decrease of fγ(max) at higher 4MP concentrations is due to the too slow crystallization rate of the γ form at these 4MP contents that induces the crystallization of the kinetically favored α form. In fact, crystals of γ forms that develop in these copolymers are highly defective and show melting temperatures lower than those of the α form and, therefore, experience low undercooling at high crystallization temperatures. These results demonstrate that in metallocene iPP copolymers containing a significant amount of constitutional defects, the crystallization of the γ form is favored because of the short regular propene sequences, whereas the crystallization of the α form is always kinetically favored.

Effect of tetrasilanolphenyl silsesquioxane on properties of sorbitol derivative-nucleated polypropylene cast films

ABSTRACT Nucleating agents cause an increase in crystallization temperature, making the production of highly oriented films much more difficult. In this study, a nucleating system composed of 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol (DMDBS) and tetrasilanolphenyl silsesquioxane (phPOSS) was used to modify isotactic polypropylene (iPP). Oriented films characterised by different draw drown ratios (4.8, 9.7, 14.5) were prepared and analysed. Their mechanical properties, coefficient of friction, thermal properties, and structure as well as optical properties such as gloss, haze, and transparency, were also determined. The macromolecular orientation of films was tested by polarised light Fourier transform infrared spectroscopy. The proposed nucleating system provides films with superior mechanical and optical properties, which are accompanied by high orientation ability. The application of DMDBS and phPOSS allowed a 26% increase in penetration load at break and Young modulus by 70% compared to iPP. It can be assumed that DMDBS/phPOSS system is an efficient modifier for polypropylene film production.

Impact of polymer chain packing and crystallization on the emission behavior of curcumin-embedded poly(L-lactide)s.

The development of biodegradable and biocompatible fluorescent materials with tunable emission in the solid state has become increasingly relevant for smart packaging and biomedical applications. Molecular packing and conformations play a critical role in tuning the solid-state photophysical properties of fluorescent materials. In this work, tunable emission of bioactive curcumin was achieved through the manipulation of the crystallization conditions and the polymorphic form of covalently linked poly(L-lactide) in the curcumin-embedded poly(L-lactide) (curcumin-PLLA). In the melt-crystallized curcumin-PLLA, with the increase in the isothermal crystallization temperature, a bathochromic shift in the fluorescence of curcumin-PLLA was observed due to the change in the intramolecular conjugation length of curcumin. The change in the isothermal crystallization temperature of curcumin-PLLA resulted in the rotation of the terminal phenyl rings of curcumin with respect to the central keto-enol group due to the covalently linked helical PLLA chains. In addition, solvent-induced single crystals and a gel of curcumin-PLLA were prepared and the influence of the polymorphic form of PLLA on the emission behavior of curcumin-PLLA was investigated. The results suggest that the polymer chain packing, crystallization conditions, morphology, and polymorphic form could play an influential role in dictating the fluorescence properties of fluorophore-embedded polymers.

Exploring influence of MgO/CaO on crystallization characteristics to understand fluidity of synthetic coal slags

The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed (EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO ratios prepared on the basis of the range of oxide contents of Zhundong coal ash were investigated in this study. The results show that with the MgO/CaO ratio increase, the initial crystallization temperature increases, and the main temperature range of crystallization ratio growth moves to higher temperature range gradually which causes Tp25 (Tp25 is the temperature corresponding to the viscosity of 25 Pa·s) to increase. Mg-rich crystals are formed preferentially than Ca-rich crystals when adding the same amount of MgO and CaO during cooling. The effective slagging operating temperature range decrease from 217 °C for the slag with a 0:4 MgO/CaO ratio to 44 °C for the slag with a 4:0 MgO/CaO ratio with the MgO/CaO ratio increase. The slags with 2:2 and 1:3 MgO/CaO ratios show similar effective slagging operating temperature range, Tp25 and the temperature corresponding to the viscosity of 2 Pa·s. However, compared with the slag with a 1:3 MgO/CaO ratio, the crystallization ratio and rate of slag with a 2:2 MgO/CaO ratio are lower within lower temperature range (1300–1200 °C), causing its lower critical viscosity temperature and wider actual operating temperature range. Of the five slags, the widest effective slagging operating temperature range and the lowest Tp25 of the slag with a 0:4 MgO/CaO ratio due to its low crystallization ratio, and wider actual operating temperature range of the slag with a 2:2 MgO/CaO ratio make the two slags suitable for slag discharge of EFB gasifier.