•DSC offers valuable information for the design of PET depolymerization systems.•Thermodynamic phenomena of PET solvolytic depolymerization were identified with DSC.•PET underwent melting point ...depression in all solvents, especially monoalcohols.•PET depolymerization before melting was only observed in the presence of NaOH.•Tandem DSC, chromatography, and MS tools offer PET solvolysis in-depth investigation.
Solvolytic depolymerization of polyethylene terephthalate (PET) is a thermo-chemical recycling route that valorizes plastic waste by recovering monomers and chemicals that can be reused for the synthesis of new polymers. This study focuses on neutral hydrolysis due to the potential environmental and economic benefits of water as depolymerization agent compared to alternative organic solvents. High-pressure crucibles were used as batch reactors in differential scanning calorimetry (DSC) to perform real-time monitoring of the thermodynamic phenomena taking place during solvolytic depolymerization of PET in varied solvent systems. PET melting point depression was found to be the main identified phenomena, with PET melting point exhibiting a drop of almost 30 °C in water and 50 °C in monoalcohol solvents like methanol and ethanol. Moreover, PET only underwent significant depolymerization prior to melting in NaOH containing systems. Gas Chromatography and Mass Spectrometry were used to study the fate of model additives and contaminants under solvolytic conditions. The uncertainty concerning these foreign substances poses a challenge for the development of PET solvolytic technologies, and the methods here provided proved to be a fast-screening technique to quantify the conversion and identify potential degradation products of model additives like 2-(2-hydroxy-5-methylphenyl) benzotriazole UV-stabilizer, 1-(methylamino) anthraquinone dye, and model contaminant (R)-(+)-limonene under hydrothermal conditions.
•Additive manufacturing of CuCrZr alloy for nuclear fusion applications.•Influence of heat treatments on CuCrZr microstructure.•Performance evaluation of CuCrZr printed with 370 W IR laser.
In this ...study, the processability of CuCrZr alloy with additive manufacturing (AM) technology and the performance achievable with Direct Age Hardening treatments for nuclear fusion applications were investigated. This copper alloy is one of the most interesting for the field: it is easier to manufacture through Laser-based additive manufacturing technology and mechanically superior compared to pure copper, and it ensures values of thermal conductivity high enough to be considered a valid substitute for pure copper in many applications.
The investigation on CuCrZr alloy was carried out in order to examine the influence of Direct Age Hardening (DAH) treatments on physical and mechanical properties. Laser Powder Bed Fusion technology was used to produce samples with CuCrZr alloy. The additive manufacturing process involved a machine provided with a 370 W IR laser and a preliminary process optimization was carried out to find the printing parameters that assured the highest density (99.15 %), which confirmed the processability of CuCrZr alloy also with low IR laser power. Then, three different DAH treatments were tested and the performance of DAHed material was compared to that of the alloy in as-built conditions. Precipitation phenomena were investigated with DSC analyses, revealing the effectiveness of the treatment already after 1 h. A deep microstructural investigation revealed a fine cellular structure formed during solidification and the presence of nanometric precipitates starting from the as-built condition. The presence of microstructural defects was also investigated. Mechanical performance and thermal conductivity were tested, too: the as-built samples showed limited properties, while very promising results for the use of additively manufactured CuCrZr components have been obtained after the DAHs. The ultimate tensile strength (UTS) and yield strength (YS) doubled the as-built values after 1 h treatment at 550 °C. The thermal conductivity reached three times the initial condition (from 100 W/mK to 300 W/mK).
Novel K5-xTlx(Mg0.5Hf1.5)(MoO4)6 (0 ≤ х ≤ 5) oxides were successfully synthesized by solid state reaction. The results indicate the formation of a continuous series of solid solutions with the ...NASICON-like structure (sp. gr. R3‾c) in the composition range 0 < x < 5. The unit-cell parameters of the solid solutions increase linearly with composition, as a consequence of thallium substitution for potassium. The cation conductivity of Tl5Mg0.5Hf1.5(MoO4)6 has been shown to exceed the conductivity of the parent potassium magnesium hafnium molybdate. The highest total conductivity of 2.49 × 10−3 S/cm was found at 831 K for Tl5Mg0.5Hf1.5(MoO4)6.
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Nowadays, a wide variety of software for 3D reconstruction from CT scans is available; they differ for costs, capabilities, a priori knowledge, and, it is not trivial to identify the most suitable ...one for specific purposes. The article is aimed to provide some more information, having set up various metrics for the evaluation of different software’s performance.
Metrics include software usability, segmentation quality, geometric accuracy, mesh properties and Dice Similarity Coefficient (DSC). Five different software have been considered (Mimics, D2P, Blue Sky Plan, Relu, and 3D Slicer) and tested on four cases; the mandibular bone was used as a benchmark.
Relu software, being based on AI, was able to solve some very intricate geometry and proved to have a very good usability. On the other side, the time required for segmentation was significantly higher than other software (reaching over twice the time required by Mimics). Geometric distances between nodes position calculated by different software usually kept below 2.5 mm, reaching 3.1 mm in some very critical area; 75th percentile q75 is generally less than 0.5 mm, with a maximum of 1.11 mm. Dealing with consistency among software, the maximum DSC value was observed between Mimics and Slicer, D2P and Mimics, and D2P and Slicer, reaching 0.96.
This work has demonstrated how mandible segmentation performance among software was generally very good. Nonetheless, differences in geometric accuracy, usability, costs and times required can be significant so that information here provided can be useful to perform an informed choice.
•Various commercial and open-source software for image segmentation are available.•Segmentation performances are crucial to choose the proper software.•Relevant metrics are usability, time required, mesh quality, and geometric accuracy.•The consistency among various software results can be measured through DSC.•Accuracy, usability, costs and times can be significantly different among software.
•New method was developed to derive kinetics from TGA–DSC at a single heating rate.•Equivalence of TGA–DSC and basket heating methods in kinetics analysis was proven.•TGA–DSC facilitates kinetics ...analysis of low temperature oxidation before ignition.•TGA–DSC is a cost effective method to analyze low temperature oxidation kinetics.
The present work was aimed at developing a method for determining the kinetics of low temperature coal oxidation based on thermogravimetric analysis and differential scanning calorimetry (TGA–DSC). The analyses of TGA–DSC on non-isothermal oxidation of three coals at a single heating rate were carried out. The measured heat release rates and derived apparent kinetic parameters of low temperature oxidation were compared with those from the tests of basket heating methods (crossing point temperature and heat release method). The results demonstrated the equivalence of the TGA–DSC technique and the basket heating methods in measuring the heat release rate and kinetics of coal oxidation in the temperature range of about 100–150°C. Moreover, the TGA–DSC method can also measure the kinetic parameters of coal oxidation at the temperatures from ∼150°C to that of ignition occurring, which were shown to be different from those at the temperatures below ∼150°C. Therefore, the TGA–DSC method developed here is promising to be applied as a cost effective technique for deriving the kinetics of low temperature oxidation to describe coal spontaneous combustion process prior to ignition.
A comparative study of the crystallinity of Polyetheretherketone by using density, DSC, XRD, and Raman spectroscopy techniques.
In this work, the microstructure of Polyetheretherketone is first ...analyzed with usual techniques such as density, Differential Scanning Calorimetry, X-ray Diffraction, and secondly, compared with Raman Spectroscopy. Assessing the degree of crystallinity of PEEK is challenging because of the different interpretation of the crystallinity according to each technique. The density measurement gives the highest most trusted absolute uncertainty for the degree of crystallinity, around 4%, compared to the other techniques. The Differential Scanning Calorimetry, usually used by the polymer community, overestimates up to 18% the degree of crystallinity due to a competitive phenomenon between crystallization and melting of PEEK over the same temperature range, and a fast crystallization. When Analyzing the X-ray Diffraction data, the degree of crystallinity is underestimated up to 11% as a consequence of the broad amorphous halo. Lastly, our investigation proves that Raman microspectroscopy is appropriate to determine the local crystallinity on the sample surface and compares 18 indicators in the same study. The 1651 cm-1 band shift has the highest correlation coefficient of 0.92 with the degree of crystallinity determined by density. This work attempts to correlate the results of degree of crystallinity of PEEK obtained by these four techniques in order to establish the best evaluation of this fundamental property for numerous applications.
•An original comparative analyse of PEEK microstructure with four techniques: density, DSC, XRD, Raman spectroscopy.•The Differential Scanning Calorimetry gives overestimate the value of the degree of crystallinity.•The X-ray diffraction gives underestimate the value of the degree of crystallinity.•Local characterization of the degree of crystallinity with Raman spectroscopy.•The band displacement at 1651 cm-1 of Raman spectroscopy has the highest correlation with the degree of crystallinity.
•(GeSe4)100-x(As2Se3)x glasses with x in the range 0 ≤ x ≤ 100 are prepared by melt quenching.•Glass forming ability and thermal stability of all these glasses are found to be high.•These glasses ...exhibit minimum fragility indicating their melts are strong.•Melts of glasses in the range 0 ≤ x ≤ 30 are super strong in nature.•They transmit IR light over a wide wavelength range.
(GeSe4)100-x (As2Se3)x glasses in the GeSe4-As2Se3 pseudo-binary joint are prepared by the melt quenching method. In this tie-line, the entire composition 0 ≤ x ≤ 100 is characterized by fixed average network connectivity of 2.40, which is considered to be optimal connectivity as the number of constraints and the number degrees of freedom available to the atoms are balanced at this average connectivity. The glass forming ability of the glasses having this average connectivity of 2.40 is usually found to be maximum. Glass transition temperature (Tg) decreases till x = 30 and remains invariant in the range 40 ≤ x ≤ 70. For x > 70, Tg shows an increasing trend. The jump in specific heat capacity (ΔCp), non-reversing heat flow (ΔHnr), Tg and the optical bandgap (Eg) show a distinct change in the composition range 40 and 70 mol.% of As2Se3. The fragility index (m) lies in the range of 15 and 32 for all the prepared glasses, representing the strong nature of these glass forming melts in the (GeSe4)100-x (As2Se3)x glasses. The viscosity as a function of reduced temperature (Tg/T) shows almost an Arrhenius nature for 0 ≤ x ≤ 70 and for x > 70, a slight deviation from the Arrhenius behviour is observed. The structural network of these glasses primarily consists of GeSe4/2 and Se-Se chains for x ≤ 30. For 40 ≤ x ≤ 70, the network is dominated by AsSe3/2 pyramidal units and As-As homopolar bonds. For x > 70, the structural network is characterized by AsSe3/2 pyramidal units. All the prepared glasses are found to transmit infrared (IR) light over a wide wavelength range from 2 to 17 μm. The super strong nature of the melts indicates that optical devices can be easily made for IR applications.
The flash point (FP) temperatures of some lubricant and base oils were measured according to ASTM D92 and ASTM D93. In addition, the thermal stability of the oils was studied using differential ...scanning calorimeter (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The DSC results showed that the FP temperatures, for each oil, were found during the first decomposition step and the temperature at the peak of the first decomposition step was usually higher than FP temperatures. The TGA results indicated that the temperature at which 17.5% weigh loss take placed (T17.5%) was nearly identical with the FP temperature (±10°C) that was measured according to ASTM D92. The deviation percentage between FP and T17.5% was in the range from −0.8% to 3.6%.
During ICTAC2020, a workshop was held on “Good laboratory practice in thermal analysis and calorimetry” for young researchers and beginners under the aegis of the Education Committee of ICTAC. ...Thermal analysis (TA) covers relationship between large number of sample properties and the temperature. Naturally, there is some technique for each property of the sample bringing versatility in TA. This review is devoted to the Workshop and has been refined for the benefit of the readers so that it helps them in obtaining useful qualitative and quantitative information about the effects of heat treatments on materials of all kinds. Recent trends in DSC, TG-FTIR, TG-MS, DMA, kinetics and nanocalorimetry have also been covered in this article.
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